exactmatch =
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There are 6373 matches found
| Name | BBrefID | Year | Span | Games | Team | League | Location |
| Ed Abbaticchio | abbati001edw | 1903 | Boston | National League | Boston, MA | ||
| Abbott | 1903 | 5/21-6/6 | Fargo | Northern League | , | ||
| Fred Abbott | abbott002har | 1903 | 4/25- | 77 g. | Cleveland | American League | Cleveland, OH |
| Spencer Abbott | abbott001spe | 1903 | 5/29-6/28 | Superior Longshoremen | Northern League | , | |
| Spencer Abbott | abbott001spe | 1903 | 7/7-8/27 | Fargo | Northern League | , | |
| Shields Abernathy | aberna000shi | 1903 | 9/1 | Pulaski | Tennessee-Alabama League | , | |
| Shields Abernathy | aberna000shi | 1903 | Montgomery Black Sox | Southern Association | , | ||
| Harry Ables | ables-001har | 1903 | Southwestern Univ | College | , | ||
| Leo Accorsini | accors001leo | 1903 | no g. | Memphis Egyptians | Southern Association | , | |
| Victor Accorsini | accors001vic | 1903 | 4/25-6/15 | Memphis Egyptians | Southern Association | , | |
| Victor Accorsini | accors001vic | 1903 | 6/18-6/22 | New Orleans Pelicans | Southern Association | , | |
| Victor Accorsini | accors001vic | 1903 | 6/25-9/5 | Memphis Egyptians | Southern Association | , | |
| Adams | adams-103--- | 1903 | 5/8-6/13 | Joplin Miners | Missouri Valley League | , | |
| Adams | adams-103--- | 1903 | +8/25+ | Anadarko IT | Independent | , | |
| Adams | adams-102--- | 1903 | +6/16-6/17+ | Giltner | Central Nebraska League | , | |
| Adams | adams-102--- | 1903 | +6/30-7/14+ | Red Cloud | Central Nebraska League | , | |
| Adams | adams-020--- | 1903 | 6/7 | Dallas Giants | Texas League | , | |
| Adams | adams-055--- | 1903 | 8/8 | Corsicana Oil Citys | Texas League | , | |
| Harry Adams | adams-005har | 1903 | 7/21-9/25 | MLB Umpire | American League | , | |
| Harry Adams | adams-006har | 1903 | 4/27-9/19 | New Orleans Pelicans | Southern Association | , | |
| Joe Adams | adams-003jos | 1903 | +5/14+ | Omaha-Cap.Hills | Independent | , | |
| Joe Adams | adams-003jos | 1903 | 8/25-9/3 | Springfield Midgets | Missouri Valley League | , | |
| Milton Adams | adams-103--- | 1903 | 5/8-6/13 | Joplin Miners | Missouri Valley League | , | |
| Milton Adams | adams-001cly | 1903 | Anadarko IT | Independent | , | ||
| Rick Adams | adams-006har | 1903 | 41 g. | New Orleans Pelicans | Southern Association | , | |
| Theodore Adams | adams-001the | 1903 | 5/22-6/6 | Helena Senators | Pacific National League | , | |
| Theodore Adams | adams-001the | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | ||
| Thomas Adams | adams-011tho | 1903 | 3 g. | Huntsville | Tennessee-Alabama League | , | |
| Merle Adkins | adkins001mer | 1903 | New York | American League | New York, NY | ||
| Merle Adkins | adkins001mer | 1903 | 7/11-9/15 | Baltimore Orioles | Eastern League | , | |
| Bert Adrian | adrian001ber | 1903 | San Antonio Bronchos | South Texas League | , | ||
| Joe Agan | agan--001jos | 1903 | +7/26+ | Atlantic | Southwest Iowa League | , | |
| Pete Agnew | agnew-001pet | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| Walter Ahearn | ahearn001wal | 1903 | 5/9-7/21 | New Haven Blues | Connecticut League | , | |
| Walter Ahearn | ahearn001wal | 1903 | 8/1-9/12 | Hartford Senators | Connecticut League | , | |
| Alvia Ahlin | ahlin-001a-- | 1903 | +6/1 | Greeley NE | Independent | , | |
| Alvia Ahlin | ahlin-001a-- | 1903 | +6/17-7/24 | Minden | Central Nebraska League | , | |
| Alvia Ahlin | ahlin-001a-- | 1903 | Holdrege NE | Independent | , | ||
| Dad Ahorn | ahorn-001a-- | 1903 | +7/8+ | Oklahoma City | Independent | , | |
| Dad Ahorn | ahorn-001a-- | 1903 | 7/15-8/29 | Galveston Sand Crabs | South Texas League | , | |
| Abe Akers | akers-001abe | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Abe Akers | akers-001abe | 1903 | +7/20+ | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | |
| Lee Akers | akers-001jak | 1903 | 5 g. | Montgomery Black Sox | Interstate League | , | |
| Lee Akers | akers-001jak | 1903 | Greenville Grays | Cotton States League | , | ||
| Lee Akers | akers-001jak | 1903 | 9/15-9/20 | Louisville Colonels | American Association | , | |
| Roy Akin | akin--001roy | 1903 | +6/11+ | Columbia TN | Independent | , | |
| Roy Akin | akin--001roy | 1903 | 7/15-8/13 | Galveston Sand Crabs | South Texas League | , | |
| Bobby Alberts | albert002rob | 1903 | 71 g. | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Cy Alberts | albert001fre | 1903 | 4/30-9/13 | Fort Wayne Railroaders | Central League | , | |
| Gus Alberts | albert001gus | 1903 | 6/23-8/24 | Umpire | Missouri Valley League | , | |
| Robert Aldrich | aldric000rob | 1903 | 6/6-6/11 | Lawrence Colts | New England League | , | |
| Bill Alexander | alexan005wil | 1903 | 6/5-7/6 | San Antonio Bronchos | South Texas League | , | |
| Bill Alexander | alexan005wil | 1903 | 7/9-8/25 | Corsicana Oil Citys | Texas League | , | |
| Bill Alexander | alexan005wil | 1903 | 8/27-8/31 | San Antonio Bronchos | South Texas League | , | |
| Alhern | alhern000--- | 1903 | 6/11 | Giltner | Central Nebraska League | , | |
| Harry Allemang | allema001har | 1903 | 5/13-7/5 | Toledo Mud Hens | American Association | , | |
| Harry Allemang | allema001har | 1903 | 7/26-9/11 | St. Paul Saints | American Association | , | |
| Allen | allen-061--- | 1903 | 6/17-7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/Webb City, | |
| Allen | allen-098--- | 1903 | 8/5 | Iola Gaslighters | Missouri Valley League | , | |
| Charlie Allen | allen-005cha | 1903 | Bates College | College | , | ||
| Charlie Allen | allen-005cha | 1903 | 6/16-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Charlie Allen | allen-005cha | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| George Allen | allen-003geo | 1903 | 5/2-7/29+ | Joplin Miners | Missouri Valley League | , | |
| Hank Allis | allis-001han | 1903 | Waterloo IA | Independent | , | ||
| Hank Allis | allis-001han | 1903 | 40 g. | Sioux City Soos | Iowa-South Dakota League | Sioux City, | |
| Allotta | allott001--- | 1903 | San Jose | California State League | , | ||
| Arthur Alloway | allowa001art | 1903 | 5/1-7/11 | Peoria Distillers | Western League | , | |
| Arthur Alloway | allowa001art | 1903 | 7/16-9/21 | Kansas City Cowboys | American Association | , | |
| Peter Allyn | allyn-001pet | 1903 | San Jose | California State League | , | ||
| Whitey Alpermann | alperm001cha | 1903 | 116 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Dave Altizer | altize001dav | 1903 | 4/22-5/30 | Toledo Mud Hens | American Association | , | |
| Dave Altizer | altize001dav | 1903 | 6/5-9/12 | Meriden Silverites | Connecticut League | , | |
| Nick Altrock | altroc001nic | 1903 | 1 g. | Boston | American League | Boston, MA | |
| Nick Altrock | altroc001nic | 1903 | 13 g. | Chicago | American League | Chicago, IL | |
| George Amberger | amberg000geo | 1903 | 6/25-8/19 | Haverhill Hustlers | New England League | , | |
| Red Ames | ames--002leo | 1903 | 5/9-8/20 | Ilion Typewriters | New York State League | , | |
| Red Ames | ames--002leo | 1903 | 2 g. | New York | National League | New York, NY | |
| Doc Amole | amole-001doc | 1903 | 5/12-7/24 | Buffalo Bisons | Eastern League | , | |
| Doc Amole | amole-001doc | 1903 | 8/8-9/25 | Providence Grays | Eastern League | , | |
| Anderson | anders105--- | 1903 | 9/7,9/22 | Baltimore Orioles | Eastern League | , | |
| Anderson | anders124--- | 1903 | 6/16 | Red Cloud | Central Nebraska League | , | |
| Andy Anderson | anders003and | 1903 | Portland Browns | Pacific Coast League | , | ||
| Andy Anderson | anders003art | 1903 | 10 g. | Portland Browns | Pacific Coast League | , | |
| Andy Anderson | anders003art | 1903 | 4/14- | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Andy Anderson | anders003art | 1903 | -10/4 | Butte Miners | Pacific National League | , | |
| Edward Anderson | 1903 | 8/6-8/24 | Dallas Giants | Texas League | , | ||
| Goat Anderson | anders003edw | 1903 | 4/30-9/16 | South Bend Greens | Central League | , | |
| John Anderson | anders010joh | 1903 | 138 g. | St. Louis | American League | St. Louis, MO | |
| Ollie Anderson | anders001oll | 1903 | Umpire | Northern League | , | ||
| Smylie Anderson | anders001s-- | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| Spike Anderson | anders003a-- | 1903 | no g. | Terre Haute Hottentots | Central League | , | |
| Spike Anderson | anders003a-- | 1903 | +6/6+ | 80 g. | Winnipeg Maroons | Northern League | , |
| Will Anderson | anders026wil | 1903 | 8/23 | Grand Forks Forkers | Northern League | , | |
| Andrews | andrew041--- | 1903 | 5/7-6/30 | Bridgeport Orators | Connecticut League | , | |
| Andrews | andrew060--- | 1903 | 8/31 | Springfield Midgets | Missouri Valley League | , | |
| Charles Andrews | andrew001cha | 1903 | 7/20-9/16 | South Bend Greens | Central League | , | |
| Charles Andrews | andrew001cha | 1903 | 8/24 | Evansville River Rats | Central League | , | |
| Doc Andrews | andrew001jay | 1903 | 76 g. | Portland Browns | Pacific Coast League | , | |
| Doc Andrews | andrew001jay | 1903 | 25 g. | Seattle Siwashes | Pacific Coast League | , | |
| George Andrews | andrew006geo | 1903 | 243 ab | Monroe Hill Citys | Cotton States League | , | |
| George Andrews | andrew006geo | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Glenn Andrews | andrew001gle | 1903 | 23 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Glenn Andrews | andrew001gle | 1903 | 8/15-8/17 | Toledo Mud Hens | American Association | , | |
| Wyman Andrus | andrus001wym | 1903 | , | ||||
| Ernest Anklam | anklam001ern | 1903 | 5/7-9/12 | Norwich Reds | Connecticut League | , | |
| Bill Annis | annis-001wil | 1903 | 5/20- | 91 g. | Winnipeg Maroons | Northern League | , |
| Samuel Apperious | apperi001wil | 1903 | Georgetown Univ. | College | , | ||
| Fred Applegate | appleg002fre | 1903 | 4/30-6/22 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Fred Applegate | appleg002fre | 1903 | 6/30-8/17 | New Orleans Pelicans | Southern Association | , | |
| Fred Applegate | appleg002fre | 1903 | 8/23-9/16 | Memphis Egyptians | Southern Association | , | |
| Jimmy Archer | archer001jam | 1903 | 6/10-7/4 | Fargo | Northern League | , | |
| Frank Arellanes | arella001fra | 1903 | San Jose | California State League | , | ||
| Frank Arellanes | arella001fra | 1903 | San Francisco Seals | Pacific Coast League | , | ||
| Jack Arick | 1903 | Southern California | , | ||||
| Joseph Arlington | arling001jos | 1903 | 5/8-6/13 | Ilion Typewriters | New York State League | , | |
| Joseph Arlington | arling001jos | 1903 | +8/17+ | St. Albans | Northern New York League | , | |
| Charlie Armbruster | armbru001cha | 1903 | 5/7-9/12 | New London Whalers | Connecticut League | , | |
| Harry Armbruster | armbru001har | 1903 | 4/30-9/26 | Providence Grays | Eastern League | , | |
| Bill Armour | armour001wil | 1903 | Cleveland | American League | Cleveland, OH | ||
| Jimmy Armstrong | armstr002jim | 1903 | 8/8 | Springfield Midgets | Missouri Valley League | , | |
| Lou Armstrong | armstr001lou | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Harry Arndt | arndt-001har | 1903 | 4/22-9/20 | Columbus Senators | American Association | , | |
| Tom Arnold | arnold002--- | 1903 | 6/24-6/27 | Galveston Sand Crabs | South Texas League | , | |
| Ed Arthur | arthur002sta | 1903 | no g. | Des Moines Undertakers | Western League | , | |
| Ed Arthur | arthur002sta | 1903 | 5/11-7/18 | Fort Wayne Railroaders | Central League | , | |
| John Arthur | arthur001joh | 1903 | Kewanee IL | Independent | , | ||
| John Arthur | arthur001joh | 1903 | +7/28-8/8+ | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| John Arthurs | 1903 | 14 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| Steve Ashe | ashe--001ste | 1903 | 5/25-6/2 | Hartford Senators | Connecticut League | , | |
| Ed Ashenbach | ashenb001edw | 1903 | 5/4-8/18 | Nashua | New England League | , | |
| Ed Ashenbach | ashenb001edw | 1903 | 9/1-9/14 | Evansville River Rats | Central League | , | |
| Ashline | ashlin000--- | 1903 | 7/4 | Minden | Central Nebraska League | , | |
| James Ashmore | ashmor001j-- | 1903 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | ||
| James Ashmore | ashmor001j-- | 1903 | Washington State | College | , | ||
| Jack Ashton | ashton001joh | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Tom Asmussen | asmuss001tho | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Spri, | ||
| Tom Asmussen | asmuss001tho | 1903 | 12 g. | Pensacola | Interstate League | , | |
| Claude Aspinwall | aspinw002--- | 1903 | 5/10-9/6 | Olympia Senators | Southwest Washington League | , | |
| Willie Aspinwall | aspinw001wil | 1903 | 5/9 | Norwich Reds | Connecticut League | , | |
| Willie Aspinwall | aspinw001wil | 1903 | 7/15 | Hartford Senators | Connecticut League | , | |
| Charlie Atherton | athert001cha | 1903 | 5/4-9/26 | Buffalo Bisons | Eastern League | , | |
| Atkinson | atkins021--- | 1903 | 6/19-6/21 | Terre Haute Hottentots | Central League | , | |
| Newt Atkinson | atkins001new | 1903 | +6/16+ | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | |
| Newt Atkinson | atkins001new | 1903 | 15 g. | Huntsville | Tennessee-Alabama League | , | |
| Raymond Attridge | attrid000ray | 1903 | 5/4-5/8 | Leavenworth White Sox | Missouri Valley League | , | |
| Raymond Attridge | attrid000ray | 1903 | 7/9-7/24 | McCook | Central Nebraska League | , | |
| Jake Atz | atz---001joh | 1903 | 4/25-7/31 | New Orleans Pelicans | Southern Association | , | |
| Jake Atz | atz---001joh | 1903 | 8/11-9/20 | Memphis Egyptians | Southern Association | , | |
| Harry Aubrey | aubrey001har | 1903 | Boston | National League | Boston, MA | ||
| Harry Aubrey | aubrey001har | 1903 | 6/5-6/19 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Jack Auslet | 1903 | Thibodaux LA | Independent | , | |||
| Jack Auslet | 1903 | Alexandria LA | Independent | , | |||
| Jimmy Austin | austin002jam | 1903 | no g. | Toledo Mud Hens | American Association | , | |
| Jimmy Austin | austin002jam | 1903 | South Bend Greens | Central League | , | ||
| Jimmy Austin | austin002jam | 1903 | Fort Wayne Railroaders | Central League | , | ||
| Charlie Babb | babb--001cha | 1903 | 4/17- | 121 g. | New York | National League | New York, NY |
| George Babbitt | babbit002geo | 1903 | 102 g. | Seattle Chinooks | Pacific National League | , | |
| George Babbitt | babbit002geo | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | ||
| George Babbitt | babbit002geo | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| George Babbitt | babbit002geo | 1903 | 7/12-8/9 | Aberdeen Pippins | Southwest Washington League | , | |
| Bachman | bachma003--- | 1903 | 7/1-7/4 | Wheeling Stogies | Central League | , | |
| Alex Backof | backof001ale | 1903 | 4/28-6/11 | Des Moines Undertakers | Western League | , | |
| Louis Bacon | bacon-001jam | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Frederick Badel | badel-001fre | 1903 | Sharon PA | Independent | , | ||
| Art Bader | bader-001art | 1903-04 | StL.-Central HS | High School | , | ||
| Frank Badger | badger001fra | 1903 | 5/4-5/26 | Terre Haute Hottentots | Central League | , | |
| Frank Badger | badger001fra | 1903 | 6/10-6/20 | Umpire | Central League | , | |
| Will Baer | baer--001wil | 1903 | 5/21-6/12+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Will Baer | baer--001wil | 1903 | 6/19- | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Charles Baerwald | baerwa001cha | 1903 | 4/25- | 19 g. | San Francisco Pirates | Pacific National League | , |
| Charles Baerwald | baerwa001cha | 1903 | 8/1-9/17 | Denver Grizzlies | Western League | , | |
| Bagby | 1903 | Augusta GA | Independent | , | |||
| Jack Bagley | bagley001joh | 1903 | +5/12+ | Pottsville PA | Independent | , | |
| George Bailey | bailey001ger | 1903 | Springfield HS | High School | , | ||
| George Bailey | bailey001ger | 1903 | E. Longmeadow | Independent | , | ||
| George Bailey | bailey001ger | 1903 | 5/16-6/7 | Springfield Ponies | Connecticut League | , | |
| Harvey Bailey | bailey003har | 1903 | 4/23-8/1 | Columbus Senators | American Association | , | |
| Harvey Bailey | bailey003har | 1903 | 8/6-9/19 | St. Paul Saints | American Association | , | |
| King Bailey | bailey001kin | 1903 | 4/29-8/10 | Nashville Volunteers | Southern Association | , | |
| King Bailey | bailey001kin | 1903 | +9/2-9/4+ | 6 g. | Columbia | Tennessee-Alabama League | , |
| James Baird | baird-001jam | 1903 | 4/30-5/6 | Atlanta Crackers | Southern Association | , | |
| Ernie Baker | baker-002ear | 1903 | 22-9 | Baton Rouge Red Sticks | Cotton States League | , | |
| John Baker | baker-001joh | 1903 | 6 g. | Sacramento Senators | Pacific Coast League | , | |
| John Baker | baker-001joh | 1903 | 4/15- | 20 g. | Tacoma Tigers | Pacific National League | , |
| L. G. Baker | baker-000lg- | 1903 | Northern New York League | , | |||
| Roy Baker | baker-003roy | 1903 | 5/10-9/5 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| O. H. Baldwin | baldwi001h-- | 1903 | 5/2-5/26 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Balis | balis-000--- | 1903 | +6/17-6/18+ | Minden | Central Nebraska League | , | |
| Art Ball | ball--003art | 1903 | Sycamore IL | Independent | , | ||
| Eugene Ball | ball--001eug | 1903 | 5/2-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Harry Ball | ball--003har | 1903 | 5/1- | Fall River Indians | New England League | , | |
| Harry Ball | ball--003har | 1903 | -9/12 | Haverhill Hustlers | New England League | , | |
| Neal Ball | ball--001cor | 1903 | 8/1-8/29 | Toledo Mud Hens | American Association | , | |
| Neal Ball | ball--001cor | 1903 | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | ||
| Walter Ball | 1903 | Chic.-UnionGiants | Independent | , | |||
| Jim Ballantyne | ballen001jam | 1903 | +5/9-7/21+ | Wilmington DE | Independent | , | |
| Marty Ballinger | ballin002mar | 1903 | 5/3 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Joseph Bammert | bammer001joh | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Oscar Bandelin | bandel002osc | 1903 | U. of Wisconsin | College | , | ||
| Oscar Bandelin | bandel002osc | 1903 | 6/24-10/4 | Butte Miners | Pacific National League | , | |
| Cecil Bankhead | bankhe001cec | 1903 | 5/2-7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Neva/Webb City, | |
| Cecil Bankhead | bankhe001cec | 1903 | 7/19-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Bill Bannon | bannon001wil | 1903 | 5/8-7/29 | Utica Pent-Ups | New York State League | , | |
| Bill Bannon | bannon001wil | 1903 | 8/3-9/20 | Schenectady Frog Alleys | New York State League | , | |
| George Bannon | bannon001geo | 1903 | 5/9 | New Haven Blues | Connecticut League | , | |
| George Bannon | bannon001geo | 1903 | 4/30-9/26 | Newark Sailors | Eastern League | , | |
| Jimmy Bannon | bannon001jam | 1903 | 4/22-9/20 | Columbus Senators | American Association | , | |
| Tom Bannon | bannon001tho | 1903 | 5/7-9/12 | New London Whalers | Connecticut League | , | |
| Ernie Bantz | bantz-001e-- | 1903 | +6/5-7/24+ | Fort Dodge IA | Independent | , | |
| Billy Barber | barber001wil | 1903 | Ionia MI | Independent | , | ||
| Dave Barber | barber001dav | 1903 | 5/11-9/19 | Utica Pent-Ups | New York State League | , | |
| Frank Barber | barber001fra | 1903 | 26 g. | Seattle Siwashes | Pacific Coast League | , | |
| Frank Barber | barber001fra | 1903 | 5/2-8/15 | Denver Grizzlies | Western League | , | |
| Louis Barbour | barbou001lou | 1903 | 5/2-8/26 | San Antonio Bronchos | South Texas League | , | |
| George Barclay | barcla001geo | 1903 | 108 g. | St. Louis | National League | St. Louis, MO | |
| Billy Barker | barker002bil | 1903 | 7/29-8/1 | New London Whalers | Connecticut League | , | |
| Billy Barker | barker002bil | 1903 | no g. | Norwich Reds | Connecticut League | , | |
| Harry Barker | barker001har | 1903 | 34 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| G. Barksdale | 1903 | Winston-Salem | Independent | , | |||
| Harry Barndollar | barndo001har | 1903 | +6/21+ | Coffeyville KS | Independent | , | |
| William Barnes | barnes001wil | 1903 | +9/2-9/10+ | 18 g. | Pulaski | Tennessee-Alabama League | , |
| Bill Barnett | barnet010--- | 1903 | +5/3+ | U. Tennessee | College | , | |
| Bill Barnett | barnet021--- | 1903 | 6/15-7/19 | Anniston Invincibles | Alabama-Georgia League | , | |
| Bill Barnett | barnet010--- | 1903 | +8/27-9/12 | Decatur | Tennessee-Alabama League | , | |
| Jack Barnett | barnet003joh | 1903 | 5/3-9/25 | Jersey City Skeeters | Eastern League | , | |
| Charles Barngrover | 1903 | Larned KS | Independent | , | |||
| Barnsdorfer | barnsd000--- | 1903 | 6/14 | Wheeling Stogies | Central League | , | |
| Frederick Barnstead | barnst001fre | 1903-04 | Dorchester HS | School | , | ||
| Barnwell | 1903 | Yale Univ. | College | , | |||
| Barnwell | 1903 | E. Douglas MA | Independent | , | |||
| Barnwell | 1903 | Paul Smith | Independent | , | |||
| Charley Barrett | barret002cha | 1903 | 4/25- | Fort Worth Panthers | Texas League | , | |
| Charley Barrett | barret002cha | 1903 | -8/25 | Dallas Giants | Texas League | , | |
| Edward Barrington | barrin000edw | 1903 | 5/1-5/20 | Lowell Tigers | New England League | , | |
| Ed Barrow | barrow001edw | 1903 | Detroit | American League | Detroit, MI | ||
| Barry | barry-025--- | 1903 | 8/11 | Beaumont Oil Gushers | South Texas League | , | |
| Barry | barry-022--- | 1903 | 8/31-9/1 | New Haven Blues | Connecticut League | , | |
| Jimmy Barry | barry-002jam | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| Jimmy Barry | barry-002jam | 1903 | -7/27 | Haverhill Hustlers | New England League | , | |
| John Barry | barry-002joh | 1903 | Philadelphia | National League | Philadelphia, PA | ||
| Joseph Barry | barry-003jos | 1903 | San Jose | California State League | , | ||
| Joseph Barry | barry-003jos | 1903 | Oakland Reliance | California State League | , | ||
| Thomas Barry | barry-002tom | 1903 | 7/11-9/12 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Thomas Barry | barry-002tom | 1903 | Bowdoin College | College | , | ||
| Tom Barry | barry-001tho | 1903 | 5/2-8/9 | Des Moines Undertakers | Western League | , | |
| Tom Barry | barry-001tho | 1903 | 8/14-9/17 | Peoria Distillers | Western League | , | |
| Charles Barthel | barthe000cha | 1903 | 6/17 | Leavenworth White Sox | Missouri Valley League | , | |
| John Barthold | bartho001joh | 1903 | Coatesville PA | Independent | , | ||
| John Barthold | bartho001joh | 1903 | Chester PA | Independent | , | ||
| John Barthold | bartho001joh | 1903 | Lawrence Colts | New England League | , | ||
| John Barthold | bartho001joh | 1903 | Harrisburg PA | Independent | , | ||
| John Barthold | bartho001joh | 1903 | postseason | Philadelphia | American League | Philadelphia, PA | |
| R. L. Bartholomew | bartho000rl- | 1903 | 9/11-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| J. L. Bartis | 1903 | Winnipeg Maroons | Northern League | , | |||
| Bill Bartley | bartle001wil | 1903 | 4/25-8/27 | Beaumont Oil Gushers | South Texas League | , | |
| Bill Bartley | bartle001wil | 1903 | 8/31 | Galveston Sand Crabs | South Texas League | , | |
| Bill Bartley | bartle001wil | 1903 | 9/15 | New York | National League | New York, NY | |
| John Bartley | bartle001joh | 1903 | 4/25-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Harry Barton | barton001har | 1903 | +7/6-7/22+ | Wilmington DE | Independent | , | |
| James Barton | barton001jam | 1903 | 5/1-5/29 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| James Barton | barton001jam | 1903 | 5/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Jack Bartos | bartos001joh | 1903 | 5/20- | 39 g. | Winnipeg Maroons | Northern League | , |
| Jack Bartos | bartos001joh | 1903 | 9/17-9/20 | St. Paul Saints | American Association | , | |
| Forest Bashore | bashor001for | 1903 | Paulding OH | Independent | , | ||
| Forest Bashore | bashor001for | 1903 | 7/16-8/24 | Dallas Giants | Texas League | , | |
| Forest Bashore | bashor001for | 1903 | 8/28-9/6 | Dallas | Playoffs | , | |
| Jimmy Bass | bass--001jam | 1903 | 5/10 | Schenectady Frog Alleys | New York State League | , | |
| Jimmy Bass | bass--001jam | 1903 | 5/27 | Holyoke Paperweights | Connecticut League | , | |
| Jimmy Bass | bass--001jam | 1903 | 6/9-6/22 | New London Whalers | Connecticut League | , | |
| Jimmy Bass | bass--001jam | 1903 | 6/25-7/21 | Holyoke Paperweights | Connecticut League | , | |
| Jimmy Bass | bass--001jam | 1903 | 8/21-9/2 | New Orleans Pelicans | Southern Association | , | |
| Frank Bassett | 1903 | 5/21-? | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| John Bassey | bassey001joh | 1903 | StL.-White Seals | Independent | , | ||
| John Bassey | bassey001joh | 1903 | +8/23-9/23 | Springfield Midgets | Missouri Valley League | , | |
| Emil Batch | batch-001emi | 1903 | 5/8-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Fred Bateman | batema001fre | 1903 | Anderson/Grand Rapids Orphans | Central League | Anderson, | ||
| Quait Bateman | batema002h-- | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Quait Bateman | batema002h-- | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Bates | bates-037--- | 1903 | +7/20-7/24 | Minden | Central Nebraska League | , | |
| Larry Battam | battam001lar | 1903 | 5/7-7/6 | Hartford Senators | Connecticut League | , | |
| Larry Battam | battam001lar | 1903 | 7/7-9/12 | Bridgeport Orators | Connecticut League | , | |
| Jacob Bauer | bauer-001jac | 1903 | 5/2-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Charles Baum | baum--002cha | 1903 | 3 g. | Los Angeles Angels | Pacific Coast League | , | |
| Frank Baxter | baxter002fra | 1903 | 5/2-5/27 | Springfield Midgets | Missouri Valley League | , | |
| Frank Baxter | baxter002fra | 1903 | 7/10 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Moose Baxter | baxter001joh | 1903 | 126 g. | Oakland Oaks | Pacific Coast League | , | |
| Harry Bay | bay---001har | 1903-08 | Cleveland | American League | Cleveland, OH | ||
| Dick Bayless | bayles001har | 1903 | 5/2-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Dick Bayless | bayles001har | 1903 | Omaha Indians | Western League | , | ||
| Alva Bayne | bayne-001alv | 1903 | Dalton GA | Independent | , | ||
| Alva Bayne | bayne-001alv | 1903 | 9/1-9/12 | Columbia | Tennessee-Alabama League | , | |
| Joe Bean | bean--001jos | 1903 | 4/30-9/25 | Jersey City Skeeters | Eastern League | , | |
| Jimmy Beard | beard-001jam | 1903 | Norristown PA | Independent | , | ||
| Jimmy Beard | beard-001jam | 1903 | 6/20-8/15 | Lawrence Colts | New England League | , | |
| Jimmy Beard | beard-001jam | 1903 | +8/18+ | Williamsport PA | Independent | , | |
| Frank Beaumont | beaumo001fra | 1903 | Woonsocket Gyms | Independent | , | ||
| Erve Beck | beck--001erv | 1903 | 4/25-9/20 | Shreveport Giants | Southern Association | , | |
| Henry Beckendorf | becken001hen | 1903 | 70 g. | Kingston Colonials | Hudson River League | , | |
| Arthur Becker | becker002art | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Bob Becker | becker001bob | 1903 | 4/30-9/26 | Rochester Bronchos | Eastern League | , | |
| Jake Beckley | beckle001jac | 1903 | 120 g. | Cincinnati | National League | Cincinnati, OH | |
| Fred Beebe | beebe-001fre | 1903 | 6/13-7/3 | Crookston Crooks | Northern League | , | |
| Harry Beecher | beeche000har | 1903 | 8/8-8/9 | New Orleans Pelicans | Southern Association | , | |
| John Beedles | beedle002joh | 1903 | 29 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| John Beedles | beedle002joh | 1903 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | ||
| William Beeker | beeker001wil | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Thomas Behan | behan-000tom | 1903 | Huntsville AL | Independent | , | ||
| Thomas Behan | behan-000tom | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Thomas Behan | behan-000tom | 1903 | 8/21-9/6+ | Huntsville | Tennessee-Alabama League | , | |
| Billy Belden | belden001wil | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| Ira Belden | belden002ira | 1903 | 4/28-9/13 | St. Joseph Saints | Western League | , | |
| Frank Belt | belt--001fra | 1903 | 83 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Frank Belt | belt--001fra | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Spri, | ||
| Harry Belt | belt--001hic | 1903 | 5/10-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Oren Beltzer | beltze001buc | 1903 | 6/15-6/29 | McCook | Central Nebraska League | , | |
| Oren Beltzer | beltze001buc | 1903 | 7/1 | Arapahoe NE | Independent | , | |
| Oren Beltzer | beltze001buc | 1903 | +7/26+ | Grand Island NE | Independent | , | |
| Charles Bemiss | bemis-001cha | 1903 | 5/21-9/8 | Winnipeg Maroons | Northern League | , | |
| Charles Bender | bender001cha | 1903 | Philadelphia | American League | Philadelphia, PA | ||
| H. Bender | bender000h-- | 1903 | 6/11-7/16+ | Giltner | Central Nebraska League | , | |
| John Bender | bender001joh | 1903 | 6/8-7/24 | McCook | Central Nebraska League | , | |
| John Bender | bender002joh | 1903 | 5/20-9/8 | Duluth Cardinals | Northern League | , | |
| John Bender | bender002joh | 1903 | U. ND Agriculture | College | , | ||
| William Benke | benke-000wil | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Bennett | bennet066--- | 1903 | 8/5-8/11+ | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Bennett | bennet034--- | 1903 | 7/22-8/8 | Beaumont Oil Gushers | South Texas League | , | |
| A. J. Bennett | bennet001a-- | 1903 | 134 ab | Monroe Hill Citys | Cotton States League | , | |
| Davy Bennett | 1903 | Altoona PA | Independent | , | |||
| Pug Bennett | bennet001jus | 1903 | 4/17-9/18 | Atlanta Crackers | Southern Association | , | |
| Benosh | 1903 | Dayton Veterans | Central League | , | |||
| William Bentley | bentle001wil | 1903 | Columbia SC | Independent | , | ||
| Berger | berger029--- | 1903 | 8/6-8/7 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Heinie Berger | berger001cha | 1903 | Piqua OH | Independent | , | ||
| Heinie Berger | berger001cha | 1903 | 7/19-9/19 | Columbus Senators | American Association | , | |
| James Berger | berger001jam | 1903 | Hudson Marines | Hudson River League | , | ||
| Joseph Berger | 1903 | StL-Indep | Independent | , | |||
| C. C.? Bergiere | bergie000--- | 1903 | 7/23 | Columbus Senators | American Association | , | |
| Curt Bernard | bernar001cur | 1903 | 4/22-8/26 | Toledo Mud Hens | American Association | , | |
| Sam Bernard | bernar001sam | 1903 | 5/1- | Haverhill Hustlers | New England League | , | |
| Sam Bernard | bernar001sam | 1903 | -9/12 | Lawrence Colts | New England League | , | |
| Bill Bernhard | bernha001wil | 1903 | 20 g. | Cleveland | American League | Cleveland, OH | |
| Archibald Bero | bero--001arc | 1903 | 8/2 | Wheeling Stogies | Central League | , | |
| Archibald Bero | bero--001arc | 1903 | 9/8-9/16 | Dayton Veterans | Central League | , | |
| Berry | 1903 | +5/14-6/14 | Walla Walla | Inland Empire League | , | ||
| Claude Berry | berry-001cla | 1903 | 4/26-8/25 | Dallas Giants | Texas League | , | |
| Claude Berry | berry-001cla | 1903 | 9/18-9/19 | Louisville Colonels | American Association | , | |
| Harry Berry | berry-002har | 1903 | 133 ab | Baton Rouge Red Sticks | Cotton States League | , | |
| Hodge Berry | berry-000hod | 1903 | 5/8-6/13 | Springfield Ponies | Connecticut League | , | |
| Joe Berry | berry-001jos | 1903 | 5/1- | Concord Marines | New England League | , | |
| Joe Berry | berry-001jos | 1903 | -9/12 | Haverhill Hustlers | New England League | , | |
| Bob Berryhill | berryh001rob | 1903 | 7/11-8/12 | Umpire | Western League | , | |
| Bob Berryhill | berryh001rob | 1903 | 9/5-9/15 | Umpire | Western League | , | |
| Harry Berte | berte-001har | 1903 | 113 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Harry Berte | berte-001har | 1903 | 9/17-9/22 | St. Louis | National League | St. Louis, MO | |
| W. R. Bess | bess--002--- | 1903 | 5/10-5/31 | Olympia Senators | Southwest Washington League | , | |
| Conrad Best | best--001con | 1903 | 5/16 | Nashville Volunteers | Southern Association | , | |
| Conrad Best | best--001con | 1903 | 6/7-6/19 | Memphis Egyptians | Southern Association | , | |
| Conrad Best | best--001con | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Frank Betts | 1903 | 4/25-4/27 | Umpire | South Texas League | , | ||
| Frank Betts | 1903 | Umpire | Texas League | , | |||
| Fred Betts | betts-001fre | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Harry Betts | betts-002har | 1903 | 9/22 | St. Louis | National League | St. Louis, MO | |
| Bevan | bevan-002--- | 1903 | +6/18-7/24 | Minden | Central Nebraska League | , | |
| Frank Bevier | bevier001fra | 1903 | 5/1-7/8 | Lawrence Colts | New England League | , | |
| Monte Beville | bevill001hen | 1903 | New York | American League | New York, NY | ||
| Monte Beville | bevill001hen | 1903 | MLB Umpire | American League | , | ||
| Kid Bevis | bevis-001e-- | 1903 | 6/19-6/19 | Fort Scott Giants | Missouri Valley League | , | |
| Roy Bevis | bevis-001roy | 1903 | 5/3-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Joseph Bewer | bewer-001jos | 1903 | 52 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Ed Biecher | bieche001ed- | 1903 | 4/30-9/13 | Terre Haute Hottentots | Central League | , | |
| George Bigbie | bigbie001geo | 1903 | 5/1-9/12 | Lowell Tigers | New England League | , | |
| Harry Billett | billet001har | 1903 | York PA | Independent | , | ||
| Charles Bilyeu | bilyeu000cha | 1903 | Albany | Willamette Valley | Albany, OR | ||
| Charles Bilyeu | bilyeu000cha | 1903 | Albany College | College | , | ||
| Daniel Binnard | 1903 | 4/30- | Colfax | Inland Empire League | , | ||
| Bert Bircher | 1903 | +6/10-7/24 | Atlantic | Southwest Iowa League | , | ||
| Harry Bird | bird--001har | 1903 | Oakland Heeseman | California State League | , | ||
| Harry Bird | bird--001har | 1903 | 25 g. | Oakland Oaks | Pacific Coast League | , | |
| Joe Birmingham | birmin001jos | 1903 | Elmira NY | Independent | , | ||
| Mike Birmingham | birmin001mic | 1903 | 6/11-6/30 | Peoria Distillers | Western League | , | |
| Charles Bishop | bishop002cha | 1903 | 31 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| John Bishop | bishop001joh | 1903 | 5/9-5/18 | Schenectady Frog Alleys | New York State League | , | |
| Wilbert Bissell | bissel001wil | 1903 | Fort Wayne Railroaders | Central League | , | ||
| Bob Black | black-002bob | 1903 | 63 g. | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Cyrus Black | black-001cyr | 1903 | 6/8-7/24 | Holdredge | Central Nebraska League | , | |
| Harry Black | black-001har | 1903 | Worcester | , | |||
| Harry Black | black-001har | 1903 | +10/3+ | Gloucester NJ | Independent | , | |
| Robert Black | black-003bob | 1903 | 5/21-7/26+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Charles Blackburn | blackb001cha | 1903 | 4/26-6/21 | Galveston Sand Crabs | South Texas League | , | |
| Charles Blackburn | blackb001cha | 1903 | 6/30-8/29 | Houston Buffaloes | South Texas League | , | |
| George Blackburn | blackb001geo | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Blair | blair-017--- | 1903 | Addison NY | Independent | , | ||
| Guy Blair | blair-001guy | 1903 | 5/20- | 33 g. | Superior Longshoremen | Northern League | , |
| Walter Blair | blair-001wal | 1903-07 | Bucknell Univ. | College | , | ||
| Walter Blair | blair-001wal | 1903 | 5/1-7/5 | Corsicana Oil Citys | Texas League | , | |
| Walter Blair | blair-001wal | 1903 | Coudersport PA | Independent | , | ||
| Bill Blake | blake-001wil | 1903 | 4/30-5/5 | Wheeling Stogies | Central League | , | |
| Bill Blake | blake-001wil | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Bill Blake | blake-001wil | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Bill Blake | blake-001wil | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Frank Blake | blake-001wil | 1903 | 4/30-5/5 | Wheeling Stogies | Central League | , | |
| Frank Blake | blake-001wil | 1903 | Greenville Grays | Cotton States League | , | ||
| Harry Blake | blake-001har | 1903 | 4/30-7/4 | Rochester Bronchos | Eastern League | , | |
| Harry Blake | blake-001har | 1903 | 114 g. | Portland Browns | Pacific Coast League | , | |
| Bill Blakey | blakey001wil | 1903 | 6/5-6/12 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Bill Blakey | blakey001wil | 1903 | 6/28-9/16 | Wheeling Stogies | Central League | , | |
| Blanchard | blanch019--- | 1903 | 5/22-5/23 | Sedalia Goldbugs | Missouri Valley League | , | |
| Blankenbacker | blanke005--- | 1903 | 9/15 | Marion Oilworkers | Central League | , | |
| Cliff Blankenship | blanke001cli | 1903 | 4/22-8/26 | Toledo Mud Hens | American Association | , | |
| Cliff Blankenship | blanke001cli | 1903 | +9/7+ | Columbus GA | Independent | , | |
| Arch Blasingim | blasin001a-- | 1903 | 8/14-8/15 | Beaumont Oil Gushers | South Texas League | , | |
| Bob Blewett | blewet001rob | 1903 | 4 g. | Seattle Siwashes | Pacific Coast League | , | |
| Bob Blewett | blewet001rob | 1903 | +5/30+ | 22 g. | Tacoma Tigers | Pacific National League | , |
| Bob Blewett | blewet001rob | 1903 | 8/23 | Olympia Senators | Southwest Washington League | , | |
| Bob Blincoe | blinco001rob | 1903 | 129 ab | Baton Rouge Red Sticks | Cotton States League | , | |
| Bob Blincoe | blinco001rob | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Bob Blincoe | blinco001rob | 1903 | -9/15 | Pine Bluff Lumbermen | Cotton States League | , | |
| Elmer Bliss | bliss-001elm | 1903 | 5/10-9/18 | Utica Pent-Ups | New York State League | , | |
| Elmer Bliss | bliss-001elm | 1903 | 9/28 | New York | American League | New York, NY | |
| Albert Blough | blough000as- | 1903 | Evansville River Rats | Central League | , | ||
| J. A. Blough | 1903 | College of Medi. | , | ||||
| J. A. Blough | 1903 | +5/16+ | Harrisburg PA | Independent | , | ||
| J. A. Blough | 1903 | 8/? | Wilmington DE | Independent | , | ||
| Curley Blount | blount001iow | 1903 | 6/27- | Youngstown OH | Independent | , | |
| Bert Blue | blue--001bir | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| F. Blumrich | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| George Boardman | boardm001geo | 1903 | 5/1-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| George Boardman | boardm001geo | 1903 | 6/26-7/25 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Boaz | boaz--000--- | 1903 | 9/25 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| John Bockstahler | bockst001j-- | 1903 | Penn Yan NY | Independent | , | ||
| Oscar Boettiger | boetti001osc | 1903 | 5/31-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Oscar Boettiger | boetti001osc | 1903 | 7/7 | Tacoma Tigers | Pacific National League | , | |
| Richard Boettiger | boetti001ric | 1903 | Oakland Heeseman | California State League | , | ||
| Richard Boettiger | boetti001ric | 1903 | 77 g. | Seattle Siwashes | Pacific Coast League | , | |
| Blackburn Bohannon | bohann001l-- | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Luke Bohannon | bohann001l-- | 1903 | -6/1 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |
| Luke Bohannon | bohann001l-- | 1903 | +6/16+ | Lexington KY | Independent | , | |
| Luke Bohannon | bohann001l-- | 1903 | 6/27-9/15 | Evansville River Rats | Central League | , | |
| Patrick Bohannon | bohann001pat | 1903 | 4/22-9/17 | Louisville Colonels | American Association | , | |
| Bolen | bolen-000--- | 1903 | 8/15-8/21 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Boylen? Bolin | bolin-004--- | 1903 | 5/3-5/4 | Evansville River Rats | Central League | , | |
| John Bolin | bolin-003joh | 1903 | 4/22 | Minneapolis Millers | American Association | , | |
| John Bolin | bolin-003joh | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| John Bolin | bolin-003joh | 1903 | 8/5-9/19 | Little Rock Travelers | Southern Association | , | |
| Charles Bomar | bomar-001cha | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Charles? Bomar | bomar-001--- | 1903 | 5/2-5/6 | San Antonio Bronchos | South Texas League | , | |
| Bond | bond--010--- | 1903 | 8/24-8/27 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| George Bone | bone--001geo | 1903 | 5/7-9/12 | New Haven Blues | Connecticut League | , | |
| Frank Bonner | bonner001fra | 1903 | - 6/25 | 48 g. | Boston | National League | Boston, MA |
| Frank Bonner | bonner001fra | 1903 | Worcester MA | Independent | , | ||
| Jack Bonner | bonner001joh | 1903 | 5/2-9/15 | Evansville River Rats | Central League | , | |
| Joseph Bonner | 1903 | +10/4+ | Drifton PA | Independent | , | ||
| Frank Bonnett | bonnet001fra | 1903 | 35 g. | Dayton Veterans | Central League | , | |
| Gus Bonno | bonno-001gus | 1903 | Columbus Senators | American Association | , | ||
| Harry Bonthrom | 1903 | 5/20-9/8 | Fargo | Northern League | , | ||
| Booth | 1903 | Williamsport | , | ||||
| Booth | booth-006--- | 1903 | 5/25-5/30 | Albany Senators | New York State League | , | |
| George Booth | booth-001geo | 1903 | Hornellsville NY | Independent | , | ||
| George Borchers | borche001geo | 1903 | 4/16-8/13+ | San Francisco Pirates | Pacific National League | , | |
| Edwin Bosler | bosler001edw | 1903 | +6/10-6/15+ | Denver Grizzlies | Western League | , | |
| Edwin Bosler | bosler001edw | 1903 | 6/29-8/8 | Evansville River Rats | Central League | , | |
| Edwin Bosler | bosler001edw | 1903 | 8/9-9/13 | Umpire | Central League | , | |
| Billy Bothwell | bothwe001wil | 1903 | 6/21 | Olympia Senators | Southwest Washington League | , | |
| Billy Bothwell | bothwe001wil | 1903 | +7/12+ | Olympia-Clerks | Independent | , | |
| Billy Bottenus | botten001wil | 1903 | 5/8-8/23 | Schenectady Frog Alleys | New York State League | , | |
| Jim Bouldin | bouldi001jam | 1903 | 5/2-7/31 | Iola Gaslighters | Missouri Valley League | , | |
| Victor Bourdon | bourdo000vic | 1903 | 6/28-7/14 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Victor Bourdon | bourdo000vic | 1903 | 7/21-9/12 | Hartford Senators | Connecticut League | , | |
| Benny Bowcock | bowcoc001ben | 1903 | 5/28-9/12 | Fall River Indians | New England League | , | |
| Benny Bowcock | bowcoc001ben | 1903 | 9/18-9/28 | St. Louis | American League | St. Louis, MO | |
| Ernest Bowden/Bord | 1903 | 7/31-8/19 | Manchester | New England League | , | ||
| Cy Bowen | bowen-001sut | 1903 | 5/2-6/28 | New Orleans Pelicans | Southern Association | , | |
| Cy Bowen | bowen-001sut | 1903 | 7/22 | Birmingham Barons | Southern Association | , | |
| Frank Bowerman | bowerm001fra | 1903 | 64 g. | New York | National League | New York, NY | |
| George Bowers | bowers001geo | 1903 | 5/4 | Haverhill Hustlers | New England League | , | |
| Rube Bowers | bowers001d-- | 1903 | York-Penn Park | Independent | , | ||
| Goldie Bowler | bowler001p-- | 1903 | 5/8-9/11 | Springfield Ponies | Connecticut League | , | |
| Frank Bowman | bowman001fra | 1903 | Los Angeles | Pacific National League | , | ||
| Frank Bowman | bowman001fra | 1903 | 4/14-4/24+ | Tacoma Tigers | Pacific National League | , | |
| M. H. Bowman | 1903 | Yale Univ. | College | , | |||
| William Bowman | bowman006wil | 1903 | West Virginia U | College | , | ||
| William Bowman | bowman006wil | 1903 | no g. | Philadelphia | National League | Philadelphia, PA | |
| William Bowman | bowman006wil | 1903 | 5/21-6/17 | St. Joseph Saints | Western League | , | |
| Boyd | boyd--052--- | 1903 | 7/30 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Earl Boyd | boyd--001ear | 1903 | Zanesville OH | , | |||
| Earl Boyd | boyd--001ear | 1903 | 7/19-7/30 | San Antonio Bronchos | South Texas League | , | |
| E. C. Boykin | boykin000ec- | 1903 | 1 g. | Brewton | Interstate League | , | |
| Charles Boylan | boylan000cha | 1903 | +6/12-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Charles Boylan | boylan000cha | 1903 | +8/1-8/9+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Boyle | boyle-018--- | 1903 | 8/19-8/22 | Ilion Typewriters | New York State League | , | |
| Frank Boyle | boyle-001fra | 1903 | Natchez Indians | Cotton States League | , | ||
| Frank Boyle | boyle-001fra | 1903 | Webster City | Independent | , | ||
| Walter Boyson | boyson000wal | 1903 | Rindge Technical | High School | , | ||
| L.P. Bradbury | bradbu000lp- | 1903 | +6/4-6/14 | Pendleton | Inland Empire League | , | |
| Bradden | bradde000--- | 1903 | 6/20-6/21 | Evansville River Rats | Central League | , | |
| Jack Bradish | bradis001--- | 1903 | 8/14-9/1 | Crookston Crooks | Northern League | , | |
| Edward Bradley | bradle001edw | 1903 | +5/28-6/12+ | Walla Walla | Inland Empire League | , | |
| Edward Bradley | bradle001edw | 1903 | 50 g. | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland/SLC, | |
| Edward Bradley | bradle001edw | 1903 | +7/30+ | Helena Senators | Pacific National League | , | |
| Ernest Bradley | bradle001ern | 1903 | Roseburg | Willamette Valley | Roseburg, OR | ||
| James Bradley | bradle001jam | 1903 | -9/9 | 26 g. | Winnipeg Maroons | Northern League | , |
| James Bradley | bradle007jam | 1903 | 5/8-5/11 | Schenectady Frog Alleys | New York State League | , | |
| James Bradley | bradle007jam | 1903 | 5/22-6/3 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Jerome Bradley | 1903 | Georgetown | College | , | |||
| Charles Brady | brady-003cha | 1903 | Umpire | Hudson River League | , | ||
| Charles Brady | brady-003cha | 1903 | Saugerties | Hudson River League | , | ||
| E. Brady | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| George Brady | brady-001bil | 1903 | +6/27+ | Pine Bluff Lumbermen | Cotton States League | , | |
| Edward Brahic | brahic000edd | 1903 | +8/23+ | Paducah-L.A.L. | Amateur | , | |
| Louis Brahic | brahic000dic | 1903 | +8/23+ | Paducah-L.A.L. | Amateur | , | |
| Edward Brahm | brahm-000edw | 1903 | +7/5+ | Massillon OH | Independent | , | |
| F. C. Braig | 1903 | Umpire | Illinois-Indiana-Iowa League | , | |||
| F. C. Braig | 1903 | 8/3-9/8 | Umpire | Northern League | , | ||
| Dave Brain | brain-001dav | 1903 | St. Louis | National League | St. Louis, MO | ||
| Edward Brandon | brando001e-- | 1903 | 5/3 | Sedalia Goldbugs | Missouri Valley League | , | |
| Kitty Brashear | brashe001nor | 1903 | 98 g. | Oakland Oaks | Pacific Coast League | , | |
| Kitty Brashear | brashe001nor | 1903 | 96 g. | Seattle Siwashes | Pacific Coast League | , | |
| Roy Brashear | brashe002roy | 1903 | -5/23 | 20 g. | Philadelphia | National League | Philadelphia, PA |
| Roy Brashear | brashe002roy | 1903 | 6/7-9/20 | Louisville Colonels | American Association | , | |
| Silver Braun | braun-005wil | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| William Robert? Braun | braun-003--- | 1903 | 4 g. | Mobile | Interstate League | , | |
| George Braxton | braxto000geo | 1903 | 5/8 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Billy Bray | bray--002wil | 1903 | 5/25-6/27+ | Umpire | Northern League | , | |
| Billy Bray | bray--002wil | 1903 | 7/?-8/5 | Crookston Crooks | Northern League | , | |
| Billy Bray | bray--002wil | 1903 | 8/6-9/8 | Superior Longshoremen | Northern League | , | |
| Breckbill | 1903 | Mt. Pleasant PA | Independent | , | |||
| Frank Breed | 1903 | Umpire | Independent | , | |||
| Jimmie Breen | breen-002jam | 1903 | Jamestown | , | |||
| Jimmie Breen | breen-002jam | 1903 | Kane PA | Independent | , | ||
| Jimmie Breen | breen-002jam | 1903 | Warren OH | Independent | , | ||
| A. J. Breitang | 1903 | Vicksburg Hill Billies | Cotton States League | , | |||
| Bill Breitenstein | breite001wil | 1903 | Greenville Grays | Cotton States League | , | ||
| Bill Breitenstein | breite001wil | 1903 | Natchez Indians | Cotton States League | , | ||
| Theodore Breitenstein | breite001the | 1903 | 4/25-9/19 | Memphis Egyptians | Southern Association | , | |
| Robin Brem | brem--000rob | 1903 | +4/10+ | Charlotte NC | Independent | , | |
| Brennan | 1903 | 5/18-5/26 | Umpire | Southern Association | , | ||
| Brennan | brenna039--- | 1903 | 5/26-6/10 | Fargo | Northern League | , | |
| Jack Brennan | brenna002jac | 1903 | 4/28-8/29 | Umpire | Western League | , | |
| Jack Brennan | brenna012joh | 1903 | 5/1-7/25 | Montgomery Black Sox | Southern Association | , | |
| Jack Brennan | brenna005joh | 1903 | +8/7+ | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| John Brennan | brenna002joh | 1903 | 5/6-7/28 | Toronto Maple Leafs | Eastern League | , | |
| John Brennan | brenna002joh | 1903 | 8/14-9/22 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| John Brennan | brenna002joh | 1903 | Clev.-Euclid Beach | Independent | , | ||
| Brent | brent-007--- | 1903 | Reading PA | Independent | , | ||
| Rube Bressler | bressl001har | 1903 | +5/30-8/18+ | Williamsport PA | Independent | , | |
| Brewington | brewin000--- | 1903 | 8/31-9/5 | Iola Gaslighters | Missouri Valley League | , | |
| Mike Breyette | breyet001mic | 1903 | 5/20-9/8 | Crookston Crooks | Northern League | , | |
| Charles Brice | brice-000cha | 1903 | Saugerties | Hudson River League | , | ||
| Marvin Bridges | bridge002mar | 1903-04 | Cumberland Univ. | College | , | ||
| Marvin Bridges | bridge002mar | 1903 | 8/11-8/20 | Columbia | Tennessee-Alabama League | , | |
| Al Bridwell | bridwe001alb | 1903 | 5/24-6/7 | Columbus Senators | American Association | , | |
| Al Bridwell | bridwe001alb | 1903 | 6/15-9/20 | Atlanta Crackers | Southern Association | , | |
| Buttons Briggs | briggs001her | 1903 | 4/30-9/26 | Toronto Maple Leafs | Eastern League | , | |
| Frank Brigham | brigha000fra | 1903 | 6/3-6/5 | Fargo | Northern League | , | |
| Frank Brigham | brigha000fra | 1903 | 7/8-7/10 | Crookston Crooks | Northern League | , | |
| Frank Brigham | brigha000fra | 1903 | St. Cloud MN | Independent | , | ||
| Charles Brinker | brinke000cha | 1903 | Lockport NY | Independent | , | ||
| Charles Brinker | brinke000cha | 1903 | 5/30 | Rochester Bronchos | Eastern League | , | |
| William Brinker | brinke001wil | 1903-05 | +5/12+ | U. of Washington | College | , | |
| Albert Briseno | brisen001alb | 1903 | 4/21-5/2 | Helena Senators | Pacific National League | , | |
| Albert Briseno | brisen001alb | 1903 | Los Angeles Angels | Pacific Coast League | , | ||
| George Bristow | bristo002geo | 1903 | 116 g. | Helena Senators | Pacific National League | , | |
| George Bristow | bristo002geo | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| Sherman Bristow | bristo001she | 1903 | 5/26 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| William Brittsan | britts001w-- | 1903 | +7/4-8/20+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| William Broadhurst | broadh001wil | 1903 | 1 g. | Seattle Siwashes | Pacific Coast League | , | |
| King Brockett | brocke001lew | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Billy Brockhoff | brockh001wil | 1903 | 4/14-5/16 | Butte Miners | Pacific National League | , | |
| Billy Brockhoff | brockh001wil | 1903 | +5/25-6/4+ | Pendleton | Inland Empire League | , | |
| Charlie Brockway | brockw000cha | 1903 | Calumet | , | |||
| Charlie Brockway | brockw000cha | 1903 | +9/2-9/8 | Duluth Cardinals | Northern League | , | |
| Antone Brodahl | brodah001--- | 1903 | 5/10-6/14 | Aberdeen Pippins | Southwest Washington League | , | |
| Antone Brodahl | brodah001--- | 1903 | 6/21-7/5 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Matt Broderick | broder001mat | 1903 | 5/1-5/6 | Brooklyn | National League | Brooklyn, NY | |
| Matt Broderick | broder001mat | 1903 | no g. | Denver Grizzlies | Western League | , | |
| Matt Broderick | broder001mat | 1903 | Wilmington DE | Independent | , | ||
| William Broderick | broder001wil | 1903 | 7/27-7/31 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Steve Brodie | brodie001wal | 1903 | 4/30-6/1 | Baltimore Orioles | Eastern League | , | |
| Steve Brodie | brodie001wal | 1903 | 6/11-8/11 | Toronto Maple Leafs | Eastern League | , | |
| Steve Brodie | brodie001wal | 1903 | 8/19-9/18 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Michael Brophy | brophy000mic | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Frederick Broshard | brosha001f-- | 1903 | +7/4+ | Geneva NY | Independent | , | |
| Art Brouthers | brouth001art | 1903 | 4/26-5/17 | Shreveport Giants | Southern Association | , | |
| Art Brouthers | brouth001art | 1903 | 5/18-9/20 | New Orleans Pelicans | Southern Association | , | |
| Dan Brouthers | brouth001den | 1903 | 16 g. | Poughkeepsie Colts | Hudson River League | , | |
| Brown | 1903 | WW-30thBattery | , | ||||
| Brown | 1903 | 5/31 | Walla Walla | Inland Empire League | , | ||
| Babe Brown | brown-004har | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Babe Brown | brown-004har | 1903 | 8/15-9/20 | New Orleans Pelicans | Southern Association | , | |
| Bob Brown | brown-027rob | 1903 | 4/14-5/2 | Helena Senators | Pacific National League | , | |
| Bob Brown | brown-027rob | 1903 | +5/14-6/4+ | Pendleton | Inland Empire League | , | |
| Bob Brown | brown-027rob | 1903 | Seattle Chinooks | Pacific National League | , | ||
| Bob Brown | brown-027rob | 1903 | 7/19-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Charles Brown | brown-030cha | 1903 | +7/19+ | Walla Walla WA | Independent | , | |
| Charlie Brown | brown-019cha | 1903 | Muncie IN | Independent | , | ||
| Dick Brown | brown-001ric | 1903 | 13 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Dick Brown | brown-001ric | 1903 | 5/20-9/8 | Grand Forks Forkers | Northern League | , | |
| Fred Brown | brown-004fre | 1903 | 5/31-7/17 | Providence Grays | Eastern League | , | |
| Fred Brown | brown-004fre | 1903 | 9/22-9/24 | Jersey City Skeeters | Eastern League | , | |
| Fred Brown | brown-005fre | 1903 | 30 g. | Sacramento Senators | Pacific Coast League | , | |
| Fred Brown | brown-009fre | 1903 | 8/14-9/7 | Hartford Senators | Connecticut League | , | |
| H. G. Brown | brown-000hg- | 1903 | Saugerties | Hudson River League | , | ||
| James Brown | brown-003jam | 1903 | 5/8-8/15 | Albany Senators | New York State League | , | |
| John Brown | brown-007jac | 1903 | Wilmington DE | Independent | , | ||
| John Brown | brown-024joh | 1903 | 5/2-5/11 | Fort Wayne Railroaders | Central League | , | |
| John Brown | brown-024joh | 1903 | 7/22 | Terre Haute Hottentots | Central League | , | |
| Mordecai Brown | brown-001mor | 1903 | 4/19- | 26 g. | St. Louis | National League | St. Louis, MO |
| R. Brown | brown-004r-- | 1903 | 5/2-7/7+ | Springfield Midgets | Missouri Valley League | , | |
| Rollo Brown | brown-003rol | 1903 | +8/30+ | 42 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , |
| Sam Brown | brown-003sam | 1903 | 90 g. | Birmingham Barons | Southern Association | , | |
| Stub Brown | brown-001stu | 1903 | 5/2-5/11 | Baltimore Orioles | Eastern League | , | |
| Stub Brown | brown-001stu | 1903 | +8/4+ | Balt.-Americans | Independent | , | |
| Tom Brown | brown-012tho | 1903 | 4/30-9/26 | Umpire | Eastern League | , | |
| W. J. Brown | brown-167--- | 1903 | 5/29-6/29+ | Fargo | Northern League | , | |
| Browne | 1903 | 34 g. | Le Mars Blackbirds | Iowa-South Dakota League | , | ||
| Lou Bruce | bruce-001lou | 1903 | 5/29-9/26 | Toronto Maple Leafs | Eastern League | , | |
| Frank Bruggeman | brugge001fra | 1903 | 5/21-8/30 | Sioux City Soos | Iowa-South Dakota League | , | |
| Will Bruner | bruner003wil | 1903 | 4/30-5/18 | Omaha Indians | Western League | , | |
| Will Bruner | bruner003wil | 1903 | 6/15- | Rome Romans | Alabama-Georgia League | , | |
| Ed Bruyette | bruyet001edw | 1903 | +5/28-6/14 | Walla Walla | Inland Empire League | , | |
| Ed Bruyette | bruyet001edw | 1903 | 6/28-9/5 | Centralia Midgets | Southwest Washington League | , | |
| Ed Bruyette | bruyet001edw | 1903 | 9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Clarence Bryan | bryan-003cla | 1903 | Jacksonville FL | Independent | , | ||
| Clarence Bryan | bryan-003cla | 1903 | U. of Florida | College | , | ||
| Frank Bryan | bryan-001fra | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Bryant | bryant023--- | 1903 | 8/9 | Beaumont Oil Gushers | South Texas League | , | |
| George Bubser | bubser001geo | 1903 | no g. | Des Moines Undertakers | Western League | , | |
| Buchanan | buchan004--- | 1903 | 8/30-9/17 | Colorado Springs Millionaires | Western League | , | |
| Frank Buchanan | buchan001fra | 1903 | +7/4+ | Nash.-Independen. | Amateur | , | |
| Frank Buchanan | buchan001fra | 1903 | 8/22-8/24 | Nashville Volunteers | Southern Association | , | |
| Frank Buchanan | buchan001fra | 1903 | +9/8+ | Columbia | Tennessee-Alabama League | , | |
| Jim Buchanan | buchan002jam | 1903 | 4/25-8/26 | Fort Worth Panthers | Texas League | , | |
| Al Buckenberger | bucken001al- | 1903 | Boston | National League | Boston, MA | ||
| Buckley | buckle021--- | 1903 | 7/4 | Meriden Silverites | Connecticut League | , | |
| Nathan Bucknam | buckna000nat | 1903 | Bates College | College | , | ||
| Nathan Bucknam | buckna000nat | 1903 | 6/29-7/21 | Haverhill Hustlers | New England League | , | |
| Michael Bucks | bucks-001mic | 1903 | Terre Haute Hottentots | Central League | , | ||
| Michael Bucks | bucks-001mic | 1903 | 7/18- | 15 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, |
| Percy Buckwalter | buckwa001per | 1903 | Leavenworth White Sox | Missouri Valley League | , | ||
| Percy Buckwalter | buckwa001per | 1903 | Fort Scott Giants | Missouri Valley League | , | ||
| Gus Buechle | buechl001--- | 1903 | 4/17-5/15+ | Seattle Chinooks | Pacific National League | , | |
| Gus Buechle | buechl001--- | 1903 | 6/7 | Olympia Senators | Southwest Washington League | , | |
| Gus Buechle | buechl001--- | 1903 | -7/7+ | Seattle Chinooks | Pacific National League | , | |
| Gus Buechle | buechl001--- | 1903 | +8/11+ | Everett WA | Independent | , | |
| Charlie Buelow | buelow001cha | 1903 | 106 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Fritz Buelow | buelow001fre | 1903 | 63 g. | Detroit | American League | Detroit, MI | |
| Jack Bufka | bufka-001joh | 1903 | +8/16+ | Mt. Pleasant MI | Independent | , | |
| Buhmaier | buhmai000--- | 1903 | Massillon OH | Independent | , | ||
| Ellerslie Bullard | bullar001--- | 1903 | Auburn Univ. | College | , | ||
| Ellerslie Bullard | bullar001--- | 1903 | 6/6-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Ellerslie Bullard | bullar001--- | 1903 | Oxford AL | , | |||
| Bunker | bunker000--- | 1903 | 6/11 | Lawrence Colts | New England League | , | |
| Bunker | bunker000--- | 1903 | 9/19 | Manchester | New England League | , | |
| Bunny | bunny-000--- | 1903 | 5/21-5/5 | Leavenworth White Sox | Missouri Valley League | , | |
| John Bunton | bunton001joh | 1903 | 5/4 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| John Bunton | bunton001joh | 1903 | 6/4-7/12 | Leavenworth White Sox | Missouri Valley League | , | |
| John Bunton | bunton001joh | 1903 | 7/21-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| John Bunyan | bunyan001joh | 1903 | 5/20- | Concord Marines | New England League | , | |
| John Bunyan | bunyan001joh | 1903 | Lawrence Colts | New England League | , | ||
| John Bunyan | bunyan001joh | 1903 | -9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Thomas Burbage | burbag001tho | 1903 | 5/11- | Fall River Indians | New England League | , | |
| Thomas Burbage | burbag001tho | 1903 | Brockton/New Bedford Whalers | New England League | Brockton, | ||
| Thomas Burbage | burbag001tho | 1903 | -9/12 | Lowell Tigers | New England League | , | |
| Al Burch | burch-001alb | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Fred Burchell | burche001fre | 1903 | 4/17- | 6 g. | Philadelphia | National League | Philadelphia, PA |
| Fred Burchell | burche001fre | 1903 | 6/6-9/26 | Baltimore Orioles | Eastern League | , | |
| Burdick | 1903 | 7/30-8/5+ | Umpire | Northern League | , | ||
| Peter Burg | burg--001pet | 1903 | 5/28-5/29 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Peter Burg | burg--001pet | 1903 | 5/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Burke | burke-092--- | 1903 | 9/8 | Holyoke Paperweights | Connecticut League | , | |
| Eddie Burke | burke-002edd | 1903 | Springfield Ponies | Connecticut League | , | ||
| Frank Burke | burke-002fra | 1903 | 5/9-9/12 | Meriden Silverites | Connecticut League | , | |
| James Burke | burke-101--- | 1903 | Wilmington DE | Independent | , | ||
| Jimmy Burke | burke-004jam | 1903 | 115 g. | St. Louis | National League | St. Louis, MO | |
| John Burke | burke-004joh | 1903 | Altoona PA | Independent | , | ||
| John Burke | burke-004joh | 1903 | 6/11-9/26 | Newark Sailors | Eastern League | , | |
| Joseph Burke | burke-003jos | 1903 | 5/31-6/6 | Dallas Giants | Texas League | , | |
| Joseph Burke | burke-003jos | 1903 | 6/15-8/6 | Houston Buffaloes | South Texas League | , | |
| Joseph Burke | burke-003jos | 1903 | 8/10-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Jesse Burkett | burket001jes | 1903 | St. Louis | American League | St. Louis, MO | ||
| Luther Burleson | burles002lut | 1903 | +5/15+ | Trinity Univ. | College | , | |
| Luther Burleson | burles002lut | 1903 | no g. | Corsicana Oil Citys | Texas League | , | |
| Arthur Burman | burman001art | 1903 | 6/8-7/24 | Holdredge | Central Nebraska League | , | |
| Fred Burnam | burnam001fre | 1903 | Cotton States League | , | |||
| Fred Burnam | burnam001fre | 1903 | +7/15+ | Decatur AL | Independent | , | |
| Fred Burnam | burnam001fre | 1903 | no g. | Nashville Volunteers | Southern Association | , | |
| Fred Burnam | burnam001fre | 1903 | 8/12-9/10 | Decatur | Tennessee-Alabama League | , | |
| Fred Burnam | burnam001fre | 1903 | +9/2+ | Pulaski | Tennessee-Alabama League | , | |
| Fred Burnam | burnam001fre | 1903 | 9/14- | Columbia TN | Independent | , | |
| Dad Burnett | burnet000dad | 1903 | 7/4-7/10 | Talladega Tigers | Alabama-Georgia League | , | |
| Hercules Burnett | burnet003her | 1903 | +5/21+ | 10 g. | Montgomery Black Sox | Interstate League | , |
| Hercules Burnett | burnet003her | 1903 | 7/10-9/19 | Montgomery Black Sox | Southern Association | , | |
| Burnham | 1903 | , | |||||
| Walter Burnham | burnha002wal | 1903 | 4/30-9/26 | Newark Sailors | Eastern League | , | |
| Biddy Burns | 1903 | Paulding OH | Independent | , | |||
| Billy Burns | burns-013wil | 1903 | 5/7- | Spokane Indians | Pacific National League | , | |
| Edward Burns | burns-001edw | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Gene Burns | burns-001eug | 1903 | 5/7-8/31 | Houston Buffaloes | South Texas League | , | |
| Jack Burns | burns-007joh | 1903 | 10 g. | San Francisco Seals | Pacific Coast League | , | |
| Jack Burns | burns-007joh | 1903 | 111 g. | San Francisco Pirates | Pacific National League | , | |
| Jack Burns | burns-007joh | 1903 | 9/11- | 11 g. | Detroit | American League | Detroit, MI |
| Jack Burns | burns-010joh | 1903 | 5/20-9/8 | Crookston Crooks | Northern League | , | |
| Jim Burns | burns-002jim | 1903 | 5/21-8/28+ | Fargo | Northern League | , | |
| John Burns | burns-020joh | 1903 | 6/30 | New Orleans Pelicans | Southern Association | , | |
| John Burns | burns-020joh | 1903 | 7/4-7/7 | Memphis Egyptians | Southern Association | , | |
| John Burns | burns-001joh | 1903 | Greenville Grays | Cotton States League | , | ||
| John Burns | burns-001joh | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Mike Burns | burns-001mic | 1903 | 5/10-8/31 | Umpire | South Texas League | , | |
| Borden Burr | burr--000bor | 1903 | 6/- | Talladega Tigers | Alabama-Georgia League | , | |
| Burrell | burrel003--- | 1903 | 5/21-5/24+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Frank Burrell | burrel001bus | 1903 | 5/1-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Frank Burrell | burrel001bus | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Leland Burrell | burrel000lel | 1903 | Addison NY | Independent | , | ||
| Lennius Burrell | burrel001len | 1903 | Addison NY | Independent | , | ||
| Eddie Burrill | 1903 | +7/17+ | Umpire | Central League | , | ||
| William Burroughs | 1903 | W. L. Waldrons NJ | Independent | , | |||
| Frank Burson | burson001fra | 1903 | 5/2-5/4 | Joplin Miners | Missouri Valley League | , | |
| Frank Burson | burson001fra | 1903 | 5/19-6/15 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Frank Burson | burson001fra | 1903 | 6/26-7/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Gus Burtle | burtle000gus | 1903 | 4 g. | Montgomery Black Sox | Interstate League | , | |
| Earl Burwell | burwel001ear | 1903 | +8/14-9/9+ | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Henry Busch | busch-001hen | 1903 | 4/27-9/19 | Montgomery Black Sox | Southern Association | , | |
| Fred Bush | 1903 | 7/5-9/3 | Umpire | Missouri Valley League | , | ||
| Bushey | bushey000--- | 1903 | 8/21-8/27 | Norwich Reds | Connecticut League | , | |
| Alfred Bushey | bushey001alf | 1903 | 5/11-9/11 | Lowell Tigers | New England League | , | |
| Harry Bussey | bussey001har | 1903 | 4/27-9/19 | Nashville Volunteers | Southern Association | , | |
| Harvey Bussey | bussey002har | 1903 | 5/8-8/31 | Binghamton Bingoes | New York State League | , | |
| Ike Butler | butler001isa | 1903 | 59 g. | Portland Browns | Pacific Coast League | , | |
| John Butler | butler002joh | 1903 | 4/22-6/15 | Toledo Mud Hens | American Association | , | |
| John Butler | butler002joh | 1903 | 6/19-9/20 | Kansas City Cowboys | American Association | , | |
| Peck Butler | butler001o-- | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Peck Butler | butler001o-- | 1903 | 8/21-9/6+ | Huntsville | Tennessee-Alabama League | , | |
| Will Butler | butler004wil | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Will Butler | butler004wil | 1903 | 6/26-8/23 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Edward Butman | butman001edw | 1903 | 5/7-6/1 | Hartford Senators | Connecticut League | , | |
| Butterfield | butter002--- | 1903 | Ogden-Wesslera | Independent | , | ||
| John Buttermore | butter001joh | 1903 | 5/8-5/26 | Albany Senators | New York State League | , | |
| John Buttermore | butter001joh | 1903 | 79 g. | Kingston Colonials | Hudson River League | , | |
| A. E. Butterworth | butter000ae- | 1903 | 5/8-5/18 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| A. E. Butterworth | butter000ae- | 1903 | +8/30+ | Kansas City AC | Independent | , | |
| Byers | byers-010--- | 1903 | 5/22-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Bill Byers | byers-002jam | 1903 | 4/14-8/16 | Tacoma Tigers | Pacific National League | , | |
| Bill Byers | byers-002jam | 1903 | 72 g. | Seattle Siwashes | Pacific Coast League | , | |
| Jim Byrnes | byrnes002jam | 1903 | Oakland Reliance | California State League | , | ||
| Frank Cable | cable-001fra | 1903 | 4/28-9/17 | Kansas City Blue Stockings | Western League | , | |
| Ralph Cadwalader | cadwal001ral | 1903 | Mason City IA | Independent | , | ||
| Ralph Cadwalader | cadwal001ral | 1903 | 14 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Ralph Cadwalader | cadwal001ral | 1903 | 7/21-8/25+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Ben Caffyn | caffyn001ben | 1903 | 78 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Ben Caffyn | caffyn001ben | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| John Cahill | cahill001joh | 1903 | 37 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Calametti | calame000--- | 1903 | 2 g. | Mobile | Interstate League | , | |
| Ralph Caldwell | caldwe002ral | 1903-04 | U. Pennsylvania | College | , | ||
| Dave Calhoun | calhou001dav | 1903 | no g. | Peoria Distillers | Western League | , | |
| Dave Calhoun | calhou001dav | 1903 | 19 g. | Evansville River Rats | Central League | , | |
| Dave Calhoun | calhou001dav | 1903 | Wheeling Stogies | Central League | , | ||
| H.C. Calhoun | calhou001h-- | 1903 | DeKalb Normal | College | , | ||
| H.C. Calhoun | calhou001h-- | 1903 | 10 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Jack Calhoun | calhou002joh | 1903 | Maine League | , | |||
| Jack Calhoun | calhou002joh | 1903 | 7/30-9/11 | Haverhill Hustlers | New England League | , | |
| Evelyn Califf | califf001elm | 1903 | Oregon City OR | Independent | , | ||
| M. E. Calkins | 1903 | Natchez Indians | Cotton States League | , | |||
| Callahan | callah018--- | 1903 | 23 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Jimmy Callahan | callah002jam | 1903 | Chicago | American League | Chicago, IL | ||
| Callison | callis004--- | 1903 | +7/5-7/6 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Eugene Calloway | callow000eug | 1903 | 6/14-7/9 | Selma YMCA | Alabama-Georgia League | , | |
| Eugene Calloway | callow000eug | 1903 | Greensboro AL | Independent | , | ||
| Don Cameron | camero003don | 1903 | 6/2-9/8 | Crookston Crooks | Northern League | , | |
| Frank Cameron | camero002fra | 1903 | 5/20-6/20 | Grand Forks Forkers | Northern League | , | |
| Frank Cameron | camero002fra | 1903 | +6/27-7/1+ | Fargo | Northern League | , | |
| Frank Cameron | camero002fra | 1903 | +7/13-9/8 | Winnipeg Maroons | Northern League | , | |
| Jimmy Cameron | camero001jam | 1903 | 6/9-6/10 | Lawrence Colts | New England League | , | |
| Louis Cameron | camero001lou | 1903 | Columbus GA | Independent | , | ||
| Henry Camnitz | 1903-09 | Centre College | College | , | |||
| Howie Camnitz | camnit001sam | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Count Campau | campau001cha | 1903 | 5/1-5/28 | New Orleans Pelicans | Southern Association | , | |
| Count Campau | campau001cha | 1903 | 7/14-9/20 | Binghamton Bingoes | New York State League | , | |
| Campbell | campbe092--- | 1903 | +7/22-7/24 | Giltner | Central Nebraska League | , | |
| Bill Campbell | campbe001wil | 1903 | 36 g. | Seattle Siwashes | Pacific Coast League | , | |
| Bill Campbell | campbe001wil | 1903 | 6/14-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Billy Campbell | campbe004wil | 1903 | 4/28-9/20 | Birmingham Barons | Southern Association | , | |
| Chester Campbell | campbe001che | 1903 | Stockton | California State League | , | ||
| Jack Campbell | campbe005jac | 1903 | 9/4-9/7 | Concord Marines | New England League | , | |
| Thomas Campbell | campbe002tho | 1903 | 15 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | |
| John Campion | campio001--- | 1903 | no g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Canavan | canava000--- | 1903 | 8/8 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Jim Canavan | canava001jim | 1903 | 5/23-9/12 | New Haven Blues | Connecticut League | , | |
| C. B. Canfield | canfie001c-- | 1903 | 4/27-5/15 | Dallas Giants | Texas League | , | |
| Wirt Cannell | cannel001vir | 1903 | Littleton NH | Independent | , | ||
| George Cannon | cannon001elm | 1903 | 7/23 | Wheeling Stogies | Central League | , | |
| Joe Cantillon | cantil001jos | 1903 | 9/1 | Milwaukee Brewers | American Association | , | |
| Arthur Carbiener | carbie001art | 1903 | 5/9-9/14 | Fort Wayne Railroaders | Central League | , | |
| Edward Cardow | cardow001edw | 1903 | 5/20-9/8 | Grand Forks Forkers | Northern League | , | |
| George Carey | carey-002geo | 1903 | - 7/6 | 48 g. | Washington | American League | Washington, DC |
| George Carey | carey-002geo | 1903 | 8/6-8/23 | Nashville Volunteers | Southern Association | , | |
| George Carey | carey-002geo | 1903 | 9/3-9/26 | Buffalo Bisons | Eastern League | , | |
| Bobby Cargo | cargo-001bob | 1903 | 4/27-9/20 | Nashville Volunteers | Southern Association | , | |
| Chick Cargo | cargo-001cha | 1903 | 5/8-9/20 | Albany Senators | New York State League | , | |
| Fred Carisch | carisc001fre | 1903 | 4/14-8/16 | Helena Senators | Pacific National League | , | |
| Fred Carisch | carisc001fre | 1903 | 8/31- | 5 g. | Pittsburgh | National League | Pittsburgh, PA |
| George Carisch | carris001geo | 1903 | 4/19, 7/23 | Helena Senators | Pacific National League | , | |
| George Carisch | carris001geo | 1903 | Helena Senators | Pacific National League | , | ||
| Claude Carlisle | 1903 | 5/21-9/16 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| Walter Carlisle | carlis001wal | 1903 | 80 g. | Crookston Crooks | Northern League | , | |
| Bill Carney | carney002wil | 1903 | 93 g. | Spokane Indians | Pacific National League | , | |
| Jack Carney | carney002joh | 1903 | 5/1-9/12 | Concord Marines | New England League | , | |
| E. J. Carolan | 1903 | 5/8-9/11 | Umpire | Connecticut League | , | ||
| C. F. Carpenter | 1903 | Altoona PA | Independent | , | |||
| William Carpenter | 1903 | 4/30-7/25 | Umpire | Southern Association | , | ||
| Carr | 1903 | Harvard Univ | College | , | |||
| Carr | 1903 | New London NH | Independent | , | |||
| Charlie Carr | carr--001cha | 1903 | 135 g. | Detroit | American League | Detroit, MI | |
| Hart Carr | carr--001ham | 1903 | Plattsburgh | Northern New York League | , | ||
| John Carr | carr--003joh | 1903 | 109 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Lew Carr | carr--001lew | 1903 | 4/30-9/26 | Toronto Maple Leafs | Eastern League | , | |
| Sidney Carr | carr--001sid | 1903 | Hornellsville NY | Independent | , | ||
| Bill Carrick | carric001wil | 1903 | 4/22-5/30 | Toledo Mud Hens | American Association | , | |
| Bill Carrick | carric001wil | 1903 | 22 g. | Seattle Siwashes | Pacific Coast League | , | |
| Frank Carriveau | carriv001fra | 1903 | 5/2-5/30 | Wheeling Stogies | Central League | , | |
| Frank Carriveau | carriv001fra | 1903 | 6/10-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Frank Carriveau | carriv001fra | 1903 | Rutland | Vermont League | , | ||
| Carroll | carrol050--- | 1903 | 5/8-5/14 | Troy Trojans | New York State League | , | |
| Bobby Carter | carter003rob | 1903 | 4/30-9/17 | Omaha Indians | Western League | , | |
| Charles Carter | carter005cha | 1903 | 4/30-6/14 | Dayton | Inland Empire League | , | |
| Charles Carter | carter016--- | 1903 | 6/21-7/19 | Olympia Senators | Southwest Washington League | , | |
| Charles Carter | carter005cha | 1903 | +7/28-8/5+ | Helena Senators | Pacific National League | , | |
| Charles Carter | carter005cha | 1903 | 2 g. | San Francisco Seals | Pacific Coast League | , | |
| Curtis Carter | carter004cha | 1903 | 5/2-5/19 | Leavenworth White Sox | Missouri Valley League | , | |
| Nick Carter | carter002con | 1903 | 5/9-7/23 | Syracuse Stars | New York State League | , | |
| Bob Caruthers | caruth001bob | 1903 | 56 g. | MLB Umpire | American League | , | |
| Bob Caruthers | caruth001bob | 1903 | 8/-8/16+ | Umpire | Pacific National League | , | |
| Charlie Case | case--001cha | 1903 | 35 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| W. Case | case--009--- | 1903 | 4/30-5/31+ | Colfax | Inland Empire League | , | |
| W. Case | case--009--- | 1903 | 6/28-9/6 | Centralia Midgets | Southwest Washington League | , | |
| W. Case | case--013--- | 1903 | +7/22+ | Seattle Chinooks | Pacific National League | , | |
| James Casey | casey-002jam | 1903 | 112 g. | Chicago | National League | Chicago, IL | |
| Patrick Casey | casey-001pat | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Patrick Casey | casey-001pat | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Pearl Casey | casey-001pea | 1903 | 211 g. | Sacramento Senators | Pacific Coast League | , | |
| Harry Cassady | cassad001har | 1903 | 95 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Howdy Cassiboine | cassib001how | 1903 | 6/3-7/24 | Superior Longshoremen | Northern League | , | |
| Howdy Cassiboine | cassib001how | 1903 | 7/27-8/21+ | Duluth Cardinals | Northern League | , | |
| Howdy Cassiboine | cassib001how | 1903 | +8/30-9/8 | Superior Longshoremen | Northern League | , | |
| Benny Cassidy | cassid001ber | 1903 | 5/1-7/31 | Lowell Tigers | New England League | , | |
| Benny Cassidy | cassid001ber | 1903 | 8/25-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Joe Cassidy | cassid001jos | 1903 | 55 g. | Harrisburg PA | Independent | , | |
| Pete Cassidy | cassid003pet | 1903 | 4/30-9/26 | Jersey City Skeeters | Eastern League | , | |
| Benjamin Castle | castle001ben | 1903 | Sisterville WV | Independent | , | ||
| Benjamin Castle | castle001ben | 1903 | +10/18+ | Clev.-West Ends | Independent | , | |
| Charles Castner | castne001--- | 1903 | +6/4+ | Wasco WA | Independent | , | |
| Charles Castner | castne001--- | 1903 | +7/8+ | Mt. Hood OR | Independent | , | |
| Lou Castro | castro001lou | 1903 | 4/30-5/31 | Rochester Bronchos | Eastern League | , | |
| Lou Castro | castro001lou | 1903 | 6/16-9/26 | Baltimore Orioles | Eastern League | , | |
| Eli Cates | cates-002eli | 1903 | 5/14-9/25 | Sedalia Goldbugs | Missouri Valley League | , | |
| Tom Catterson | catter001tho | 1903-08 | Villanova Univ. | College | , | ||
| Tom Catterson | catter001tho | 1903 | +8/8+ | Marlboro-Rochdale | Independent | , | |
| Cavanaugh | cavana016--- | 1903 | 6/11 | Springfield Ponies | Connecticut League | , | |
| Cavanaugh | cavana018--- | 1903 | Saugerties | Hudson River League | , | ||
| Dred Cavender | cavend001dre | 1903 | 5/5-5/26 | Birmingham Barons | Southern Association | , | |
| Dred Cavender | cavend001dre | 1903 | 5/29-5/30 | New Orleans Pelicans | Southern Association | , | |
| Dred Cavender | cavend001dre | 1903 | +6/27+ | 260 ab | Pine Bluff Lumbermen | Cotton States League | , |
| Ed Cermak | cermak001edw | 1903 | 4/25-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Chace | 1903 | Cornell Univ. | College | , | |||
| Chace | 1903 | Plattsburg NY | Independent | , | |||
| Chambers | chambe009--- | 1903 | Oakland Heeseman | California State League | , | ||
| Chuck Chandler | chandl001cha | 1903 | 5/20-7/16 | Grand Forks Forkers | Northern League | , | |
| Arthur Chapin | chapin001a-- | 1903 | Hornellsville NY | Independent | , | ||
| Chapman | chapma019--- | 1903 | 7/2-7/15 | Hartford Senators | Connecticut League | , | |
| Charles Chapman | chapma001cha | 1903 | 5/2-7/29 | Haverhill Hustlers | New England League | , | |
| William Chappelle | chappe002wil | 1903 | Winnipeg Maroons | Northern League | , | ||
| William Chappelle | chappe002wil | 1903 | 8/25-9/14 | Syracuse Stars | New York State League | , | |
| Robert Charnier | charni001rob | 1903 | Keokuk IA | Independent | , | ||
| Robert Charnier | charni001rob | 1903 | 6/- | 28 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , |
| Chauncey Chase | chase-003cha | 1903 | New Berlin WI | Independent | , | ||
| Chauncey Chase | chase-003cha | 1903 | 8/7-8/20 | Utica Pent-Ups | New York State League | , | |
| Chauncey Chase | chase-003cha | 1903 | New Berlin WI | Independent | , | ||
| Camillus Chatham | chatha000cam | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Gib Cheatum | cheatu001--- | 1903 | +6/17+ | Kingman KS | Independent | , | |
| Charlie Chech | chech-001cha | 1903 | 4/22-9/13 | St. Paul Saints | American Association | , | |
| Harry Cheek | cheek-001har | 1903 | 5/2-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| William Cherry | cherry000bil | 1903 | FtWa-Shamrocks | Independent | , | ||
| William Cherry | cherry000bil | 1903 | 6/29 | Terre Haute Hottentots | Central League | , | |
| William Cherry | cherry000bil | 1903 | 7/21-7/22 | Fort Wayne Railroaders | Central League | , | |
| William Cherry | cherry000bil | 1903 | 8/31-9/1 | Fort Wayne Railroaders | Central League | , | |
| Cheshire | cheshi000--- | 1903 | 6/12-7/28 | Talladega Tigers | Alabama-Georgia League | , | |
| Guy Chiesman | 1903-05 | +6/21 | Olivet College | College | , | ||
| Walter Chilcott | chilco001wal | 1903 | +5/12+ | Pottsville PA | Independent | , | |
| Cupid Childs | childs001cla | 1903 | 4/30-5/6 | Baltimore Orioles | Eastern League | , | |
| Cupid Childs | childs001cla | 1903 | 5/19-9/19 | Montgomery Black Sox | Southern Association | , | |
| Louis Childs | childs002lou | 1903 | 5/4-5/29 | Wheeling Stogies | Central League | , | |
| Pete Childs | childs001geo | 1903 | 4/22-6/17 | Louisville Colonels | American Association | , | |
| Pete Childs | childs001geo | 1903 | 6/26-9/20 | Toledo Mud Hens | American Association | , | |
| Pearce Chiles | chiles001pea | 1903 | Fortuna CA | Semi-professional | , | ||
| Thomas Chinn | chinn-001tho | 1903 | 4/30-9/10 | St. Joseph Saints | Western League | , | |
| John Christian | christ003j-- | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Christie | christ034--- | 1903 | +5/20+ | Salt Lake UT | Independent | , | |
| Christie | christ034--- | 1903 | +7/10+ | Helena Senators | Pacific National League | , | |
| Bill Clancy | clancy002wil | 1903 | 5/26-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Bill Clancy | clancy002wil | 1903 | 7/20-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Charles Clancy | clancy001cha | 1903 | 5/8-9/5 | Holyoke Paperweights | Connecticut League | , | |
| Clapp | clapp-001--- | 1903 | N.C.&St.Louis | Independent | , | ||
| Clapp | clapp-001--- | 1903 | 5/22-6/11+ | Columbia TN | Independent | , | |
| Clapp | clapp-001--- | 1903 | +8/20+ | 11 g. | Columbia | Tennessee-Alabama League | , |
| Clark | clark-066--- | 1903 | 4/28-5/26 | Atlanta Crackers | Southern Association | , | |
| Clark | clark-066--- | 1903 | 9/9-9/12 | Huntsville | Tennessee-Alabama League | , | |
| Clark | clark-066--- | 1903 | 1 g. | Decatur | Tennessee-Alabama League | , | |
| Clark | clark-066--- | 1903 | 9/12 | Huntsville | Tennessee-Alabama League | , | |
| Clark | clark-137--- | 1903 | +7/14-7/24 | Red Cloud | Central Nebraska League | , | |
| Clark | clark-001ler | 1903 | Brown Univ. | College | , | ||
| Clark | clark-001ler | 1903 | Newport NH | Independent | , | ||
| Dad Clark | clark-002alf | 1903 | 4/14- | 83 g. | Helena Senators | Pacific National League | , |
| Dad Clark | clark-002alf | 1903 | 7/19- | Los Angeles | Pacific National League | , | |
| Dick Clark | clark-001ric | 1903 | 4/26-8/21 | Dallas Giants | Texas League | , | |
| Ed Clark | clark-002ed- | 1903 | 7/30-8/12 | Umpire | South Texas League | , | |
| George Clark | clark-002geo | 1903 | 13 g. | Portland Browns | Pacific Coast League | , | |
| George Clark | clark-002geo | 1903 | 5/24-5/31 | Aberdeen Pippins | Southwest Washington League | , | |
| George Clark | clark-002geo | 1903 | 6/7-6/21 | Centralia Midgets | Southwest Washington League | , | |
| Ginger Clark | clark-006har | 1903 | 5/15-9/18 | Birmingham Barons | Southern Association | , | |
| Harry Clark | clark-004har | 1903 | 4/26-8/25 | Dallas Giants | Texas League | , | |
| Harry Clark | clark-004har | 1903 | 9/11-9/28 | Chicago | American League | Chicago, IL | |
| Ned Clark | clark-000ned | 1903 | +6/25+ | Cloudersport PA | Independent | , | |
| Roy Clark | clark-002roy | 1903 | 5/7-9/12 | Bridgeport Orators | Connecticut League | , | |
| Wilkie Clark | clark-001wil | 1903 | 4/27-9/19 | Montgomery Black Sox | Southern Association | , | |
| William Clark | clark-016wil | 1903 | Reading | Independent | , | ||
| Win Clark | clark-012wil | 1903 | 5/1-9/12 | Manchester | New England League | , | |
| Clarke | clarke018--- | 1903 | 6/21-7/9+ | Duluth Cardinals | Northern League | , | |
| Dad Clarke | clarke001dad | 1903 | Bottinenu ND | Independent | , | ||
| James Clarke | clarke002jam | 1903 | Hudson Marines | Hudson River League | , | ||
| Jay Clarke | clarke001jay | 1903 | 5/11-9/11 | Little Rock Travelers | Southern Association | , | |
| Josh Clarke | clarke002jos | 1903 | 4/28-9/17 | Des Moines Undertakers | Western League | , | |
| Bill Clay | clay--002fre | 1903 | York-Penn Park | Independent | , | ||
| Bill Clay | clay--002fre | 1903 | 7/20-9/12 | Meriden Silverites | Connecticut League | , | |
| Waldo Clay | clay--001wal | 1903 | 5/14-9/18 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Claycomb | 1903 | Altoona PA | Independent | , | |||
| Clayton | 1903 | Altoona PA | Independent | , | |||
| Harry Clayton | clayto001har | 1903 | 5/13-5/21 | Little Rock Travelers | Southern Association | , | |
| Harry Clayton | clayto001har | 1903 | 5/23-8/26 | Pine Bluff Lumbermen | Cotton States League | , | |
| Harry Clayton | clayto001har | 1903 | 8/28-9/15 | Baton Rouge Red Sticks | Cotton States League | , | |
| Claywell | claywe000--- | 1903 | 5/16-5/26 | Galveston Sand Crabs | South Texas League | , | |
| James Cleary | cleary001jam | 1903 | 8/19 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Clemens | 1903 | York PA | Independent | , | |||
| Wally Clement | clemen001wal | 1903 | 4/30-9/26 | Jersey City Skeeters | Eastern League | , | |
| Bill Clements | clemen004wil | 1903 | 5/3-6/25 | Providence Grays | Eastern League | , | |
| Bill Clements | clemen004wil | 1903 | 7/29-8/13 | New Haven Blues | Connecticut League | , | |
| George Cleve | cleve-001geo | 1903 | 5/1-5/11 | Dayton Veterans | Central League | , | |
| James Clifford | 1903 | Brown Univ | College | , | |||
| James Clifford | 1903 | Woonsocket RI | Independent | , | |||
| Thomas Clifford | cliffo001tho | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Edward Cline | 1903 | 4/30-9/11 | Umpire | Central League | , | ||
| Billy Clingman | clingm001wil | 1903 | 4/22-4/23 | Columbus Senators | American Association | , | |
| Billy Clingman | clingm001wil | 1903 | -7/16 | 21 g. | Cleveland | American League | Cleveland, OH |
| Billy Clingman | clingm001wil | 1903 | 7/28-9/20 | Columbus Senators | American Association | , | |
| Richard Closson | closso001ric | 1903 | 5/21-8/15+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Clow | clow--000--- | 1903 | 6/3 | Shreveport Giants | Southern Association | , | |
| Bill Clymer | clymer001wil | 1903 | 4/22-9/20 | Louisville Colonels | American Association | , | |
| Otis Clymer | clymer001oti | 1903 | +8/18+ | Williamsport PA | Independent | , | |
| John Clynes | clynes001jos | 1903 | SF-PlayerL | Amateur | , | ||
| John Clynes | clynes001jos | 1903 | 4/30-6/14 | Colfax | Inland Empire League | , | |
| John Clynes | clynes001jos | 1903 | +6/23-7/9+ | Seattle Chinooks | Pacific National League | , | |
| Andy Coakley | coakle001and | 1903 | 5/9, 5/20 | Holyoke Paperweights | Connecticut League | , | |
| Andy Coakley | coakle001and | 1903 | Lebanon NH | Independent | , | ||
| Andy Coakley | coakle001and | 1903 | 6 g. | Philadelphia | American League | Philadelphia, PA | |
| Charles Coates | coates000cha | 1903 | 5/6 | Fall River Indians | New England League | , | |
| Floyd Coates | coates001f-- | 1903 | +5/1+ | Upper Iowa Univ. | College | , | |
| Floyd Coates | coates001f-- | 1903 | Mason City IA | Independent | , | ||
| Jim Cockman | cockma001jam | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| Cocreham | cocreh001--- | 1903 | 7/5 | Corsicana Oil Citys | Texas League | , | |
| N. Cody | 1903 | Umpire | Montana State League | , | |||
| N. Cody | 1903 | 5/12- | Umpire | Pacific National League | , | ||
| Edward Coffey | coffey001edw | 1903 | 4/30-9/16 | South Bend Greens | Central League | , | |
| Dick Cogan | cogan-001dic | 1903 | 5/8-8/23 | Providence Grays | Eastern League | , | |
| Charles Cogswell | cogswe003cha | 1903 | 4/22-4/28 | Toledo Mud Hens | American Association | , | |
| Charles Cogswell | cogswe003cha | 1903 | 5/10-9/16 | South Bend Greens | Central League | , | |
| John Coker | 1903 | 6/12-8/1 | Rome Romans | Alabama-Georgia League | , | ||
| Cole | 1903 | Depew | College | , | |||
| Cole | 1903 | Grand Rapids | , | ||||
| Archie Cole | cole--001arc | 1903 | +6/24-6/25 | McCook | Central Nebraska League | , | |
| Charles Cole | cole--003cha | 1903 | 5/20-9/8 | Grand Forks Forkers | Northern League | , | |
| F. L. Cole | cole--000fl- | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Coleman | colema027--- | 1903 | 6/24 | Evansville River Rats | Central League | , | |
| Bill Coleman | 1903 | no g. | Altoona PA | Independent | , | ||
| George Coleman | colema007geo | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| William Coleman | colema005wil | 1903 | 5/12-6/24 | Galveston Sand Crabs | South Texas League | , | |
| William? Coleman | colema026--- | 1903 | 4/27 | San Antonio Bronchos | South Texas League | , | |
| William? Coleman | colema025--- | 1903 | 8/14-8/16 | Houston Buffaloes | South Texas League | , | |
| Cad Coles | coles-001cad | 1903-06 | Clemson Col | College | , | ||
| Harry Colgan | colgan001har | 1903 | 4/14-10/1 | Umpire | Pacific National League | , | |
| Cap Collars | collar001cap | 1903 | +6/14+ | Columbus City | Independent | , | |
| Dennis Collette | collet000den | 1903 | 5/21-6/5 | Crookston Crooks | Northern League | , | |
| Dennis Collette | collet000den | 1903 | White Bear MN | Independent | , | ||
| Dennis Collette | collet000den | 1903 | Stillwater | Independent | , | ||
| Collier/Collyer | 1903 | +5/22-6/4+ | Pendleton | Inland Empire League | , | ||
| Harry Colliflower | collif001har | 1903 | 5/19-7/28 | Umpire | Connecticut League | , | |
| Harry Colliflower | collif001har | 1903 | 8/7-9/26 | Umpire | Eastern League | , | |
| Collins | collin015--- | 1903 | 5/31-8/16 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Collins | collin008--- | 1903 | 3rd US Infantry | Army | , | ||
| Collins | collin008--- | 1903 | 5/14-8/6+ | Columbia TN | Independent | , | |
| Collins | collin008--- | 1903 | 8/11-9/10 | Columbia | Tennessee-Alabama League | , | |
| Chub Collins | collin001chu | 1903 | Nashua | New England League | , | ||
| Edward Collins | collin002e-- | 1903 | 4/25-7/17 | Beaumont Oil Gushers | South Texas League | , | |
| Orth Collins | collin077--- | 1903 | 4/29-5/1 | Nashville Volunteers | Southern Association | , | |
| Orth Collins | collin001ort | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| S. A. Collins | collin002e-- | 1903 | Beaumont Oil Gushers | South Texas League | , | ||
| S. Charles Collins | 1903 | 5/17-6/17 | Umpire | Missouri Valley League | , | ||
| William Collins | 1903 | Peekskill | Hudson River League | , | |||
| Jim Collopy | collop001jam | 1903 | 5/8-9/20 | Binghamton Bingoes | New York State League | , | |
| George Combs | coombs001geo | 1903 | 4/25-8/26 | Fort Worth Panthers | Texas League | , | |
| George Combs | coombs001geo | 1903 | 8/29-8/31 | Houston Buffaloes | South Texas League | , | |
| Paul Companion | compan001pau | 1903 | 5/2-9/13 | Omaha Indians | Western League | , | |
| Edward Conboy | conboy000edw | 1903 | Penn Yan NY | Independent | , | ||
| Louis Conboy | conboy001lou | 1903 | no g. | Binghamton Bingoes | New York State League | , | |
| Louis Conboy | conboy001lou | 1903 | Saugerties NY | Independent | , | ||
| Louis Conboy | conboy001lou | 1903 | 9/2-9/18 | Schenectady Frog Alleys | New York State League | , | |
| William Condon | condon000bil | 1903 | +9/5+ | Helena MT | Independent | , | |
| B. F. Cone | cone--000bf- | 1903 | Saugerties | Hudson River League | , | ||
| James Conevery | conave001j-- | 1903 | Elmira NY | Independent | , | ||
| Bunk Congalton | congal001wil | 1903 | 4/28-9/17 | Colorado Springs Millionaires | Western League | , | |
| Charles Conklin | conkli002cha | 1903 | 7/20 | Evansville River Rats | Central League | , | |
| Charles Conklin | conkli002cha | 1903 | 7/23-7/30 | Dayton Veterans | Central League | , | |
| Conley | conley023--- | 1903 | 7/23 | Bridgeport Orators | Connecticut League | , | |
| Frank Conlin | conlin001fra | 1903 | 5/2-6/30 | Leavenworth White Sox | Missouri Valley League | , | |
| Bert Conn | conn--001alb | 1903 | 89 g. | Providence Grays | Eastern League | , | |
| Ollie Conn | conn--001oli | 1903 | Umpire | Illinois-Indiana-Iowa League | , | ||
| Frank Connaughton | connau001fra | 1903 | 4/30-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Frank Connaughton | connau001fra | 1903 | 7/20-9/23 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Connell | connel033--- | 1903 | 7 g. | Superior Longshoremen | Northern League | , | |
| Jerry Connell | connel001jer | 1903 | 5/7-9/12 | New Haven Blues | Connecticut League | , | |
| Jerry Connell | connel001jer | 1903 | 9/14-9/18 | Utica Pent-Ups | New York State League | , | |
| Florence Connelly | connel000flo | 1903 | Elmira NY | Independent | , | ||
| Harry Connelly | connel001har | 1903 | 5/8 | Hartford Senators | Connecticut League | , | |
| Harry Connelly | connel001har | 1903 | 5/14-9/12 | Norwich Reds | Connecticut League | , | |
| Conners | conner009--- | 1903 | 5/12-5/22 | South Bend Greens | Central League | , | |
| Francis Connolly | connol001fra | 1903 | 5/20-5/21 | Haverhill Hustlers | New England League | , | |
| Harry Connolly | 1903 | Norwich Reds | Connecticut League | , | |||
| Patrick Connolly | connol001pat | 1903 | 7/30-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| William Connolly | connol004wil | 1903 | 5/1-9/12 | Lowell Tigers | New England League | , | |
| Jim Connor | connor001jim | 1903 | 4/30-9/23 | Providence Grays | Eastern League | , | |
| Joe Connor | connor002jos | 1903 | 5/8-9/12 | Springfield Ponies | Connecticut League | , | |
| John Connor | connor001joh | 1903 | 5/7-6/30 | Bridgeport Orators | Connecticut League | , | |
| Roger Connor | connor001rog | 1903 | 5/11-9/11 | Springfield Ponies | Connecticut League | , | |
| Connors | connor002joh | 1903 | 6/26-9/16 | Terre Haute Hottentots | Central League | , | |
| Bill Connors | connor001wil | 1903 | 64 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Bill Connors | connor002wil | 1903 | 5/1-9/12 | Lowell Tigers | New England League | , | |
| Ed Connors | connor002edw | 1903 | 4/22-5/30 | Toledo Mud Hens | American Association | , | |
| Ed Connors | connor002edw | 1903 | 6/27-8/5 | New Orleans Pelicans | Southern Association | , | |
| Ed Connors | connor002edw | 1903 | 9/3-9/17 | Milwaukee Brewers | American Association | , | |
| Ed Connors | connor002edw | 1903 | 9/21 | Minneapolis Millers | American Association | , | |
| Harlan Conover | conove001har | 1903 | 5/31-8/22 | Dallas Giants | Texas League | , | |
| John Conrad | conrad002joh | 1903 | 4/25-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Pat Conroy | conroy001pat | 1903 | 5/21-9/12 | Lawrence Colts | New England League | , | |
| Leroy Converse | conver001ler | 1903 | 6/9-7/24 | McCook | Central Nebraska League | , | |
| Leroy Converse | conver001ler | 1903 | 8/21-9/21 | Minneapolis Millers | American Association | , | |
| Dan Coogan | coogan003dan | 1903 | 5/10-9/20 | Schenectady Frog Alleys | New York State League | , | |
| C. A. Cook | cook--000ca- | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| Clarence Cook | cook--004cla | 1903 | +5/21+ | Aberdeen WA | Independent | , | |
| Dan Cook | cook--003dan | 1903 | 6/25 | New Haven Blues | Connecticut League | , | |
| George Cook | 1903 | Marysville KS | Independent | , | |||
| Herbert Cook | cook--043--- | 1903 | 5/17-7/26 | Olympia Senators | Southwest Washington League | , | |
| Herbert Cook | cook--043--- | 1903 | +7/12+ | Olympia-Clerks | Independent | , | |
| James Cook | cook--007jam | 1903 | +7/10+ | 39 g. | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, |
| Jim Cook | cook--002jam | 1903 | 7/2-7/13 | Chicago | National League | Chicago, IL | |
| Jim Cook | cook--002jam | 1903 | 7/15-9/17 | Des Moines Undertakers | Western League | , | |
| Warren Cook | 1903 | 5/29-6/30 | Pittsburg Coal Diggers | Missouri Valley League | , | ||
| Cab Cooke | cook--002c-- | 1903 | Florida | Independent | , | ||
| Duff Cooley | cooley001duf | 1903 | 138 g. | Boston | National League | Boston, MA | |
| Mel Cooley | cooley001mel | 1903 | 5/2-5/28 | Fort Scott Giants | Missouri Valley League | , | |
| Mel Cooley | cooley001mel | 1903 | Marysville KS | Independent | , | ||
| William Cooley | cooley001wil | 1903 | 4/30-9/16 | Marion Oilworkers | Central League | , | |
| George Coombs | 1903 | 4/25-8/26 | Fort Worth Panthers | Texas League | , | ||
| Cooney | cooney016--- | 1903 | 6/1-6/4 | Rochester Bronchos | Eastern League | , | |
| Bill Cooney | cooney001wil | 1903-09 | Princeton Univ. | College | , | ||
| Jack Cooney | cooney001joh | 1903 | 1 g. | San Francisco Seals | Pacific Coast League | , | |
| Jack Cooney | cooney001joh | 1903 | 1 g. | Oakland Oaks | Pacific Coast League | , | |
| Jack Cooney | cooney001joh | 1903 | 2 g. | San Francisco Seals | Pacific Coast League | , | |
| Perry Coons | coons-001per | 1903 | 4/24-6/6 | Louisville Colonels | American Association | , | |
| Perry Coons | coons-001per | 1903 | 6/15-9/21 | Kansas City Cowboys | American Association | , | |
| Frank Cooper | cooper001ike | 1903 | Lexington KY | Independent | , | ||
| George Cooper | cooper004geo | 1903 | 53 g. | Oakland Oaks | Pacific Coast League | , | |
| Henry Cooper | cooper001hen | 1903 | 6/23-7/14 | Nashua | New England League | , | |
| Jimmy Cooper | cooper002jam | 1903 | 4/27-5/7 | Nashville Volunteers | Southern Association | , | |
| Jimmy Cooper | cooper002jam | 1903 | 100 g. | Altoona PA | Independent | , | |
| T. C. Cooper | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Tommy Cope | cope--001tho | 1903 | 5/2-7/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Tommy Cope | cope--001tho | 1903 | 7/20-9/27 | Joplin Miners | Missouri Valley League | , | |
| Tommy Copeland | copela001tho | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Jack Corbett | corbet001jac | 1903 | Wausau WI | Independent | , | ||
| Joe Corbett | corbet001jos | 1903 | 79 g. | Los Angeles Angels | Pacific Coast League | , | |
| John Corbett | corbet001joh | 1903 | +5/8+ | Creston IA | Independent | , | |
| John Corbett | corbet001joh | 1903 | Shenandoah | Southwest Iowa League | , | ||
| John Corbett | corbet001joh | 1903 | 6/29-8/22+ | Creston Cyclones | Southwest Iowa League | , | |
| Ted Corbett | corbet001the | 1903 | 4/23-5/18 | St. Paul Saints | American Association | , | |
| Ted Corbett | corbet001the | 1903 | 5/25-9/8 | Winnipeg Maroons | Northern League | , | |
| Ted Corbett | corbet001the | 1903 | 9/17-9/20 | St. Paul Saints | American Association | , | |
| Harry Corbin | 1903-06 | , | |||||
| Corcoran | 1903 | Dickinson College | College | , | |||
| Corcoran | 1903 | Rochester | Catholic | , | |||
| Corcoran | 1903 | Ridgway PA | Independent | , | |||
| Phil Corcoran | corcor001phi | 1903 | 5/7-9/12 | Bridgeport Orators | Connecticut League | , | |
| Frank Corridon | corrid001fra | 1903 | , | ||||
| Francis Corrigan | corrig001f-- | 1903 | Lidgerwood ND | Semi-professional | , | ||
| Francis Corrigan | corrig001f-- | 1903 | +6/25+ | Crookston Crooks | Northern League | , | |
| Francis Corrigan | corrig001f-- | 1903 | +8/12-8/21 | Grand Forks Forkers | Northern League | , | |
| Hugh Corrigan | 1903 | Lidgerwood ND | Semi-professional | , | |||
| Jack Corrigan | corrig002joh | 1903 | Lidgerwood ND | Semi-professional | , | ||
| Jack Corrigan | corrig002joh | 1903 | 6/22-9/8 | Grand Forks Forkers | Northern League | , | |
| John Corrigan | corrig002f-- | 1903 | 5/18-7/8 | Fall River Indians | New England League | , | |
| Thomas Cosgrove | cosgro001tho | 1903 | Princeton Univ. | College | , | ||
| George Costello | costel000geo | 1903 | Cornell Univ | College | , | ||
| George Costello | costel000geo | 1903 | Red Hook NY | , | |||
| George Costello | costel000geo | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Henry Cote | cote--002hen | 1903 | 5/2-9/12 | Manchester | New England League | , | |
| John Cotter | cotter001joh | 1903 | Towanda PA | Independent | , | ||
| William Cotter | 1903 | 5/1-5/18 | Umpire | New England League | , | ||
| Cottingham | cottin001--- | 1903 | 5/21-8/30 | Dalton GA | Independent | , | |
| Coughlin | coughl006--- | 1903 | 7/9 | Rochester Bronchos | Eastern League | , | |
| Coughlin | coughl004--- | 1903 | 8/7 | Hartford Senators | Connecticut League | , | |
| John Coughlin | coughl001joh | 1903 | 5/10 | Milwaukee Creams | Western League | , | |
| John Coughlin | coughl001joh | 1903 | 5/26-6/5 | Haverhill Hustlers | New England League | , | |
| John Coughlin | coughl001joh | 1903 | 7/15-9/19 | Toledo Mud Hens | American Association | , | |
| Cy Coulter | coulte001art | 1903 | 4/22-9/20 | Indianapolis Indians | American Association | , | |
| Joe Courneen | courne001jos | 1903 | 22 g. | Fall River Indians | New England League | , | |
| Joe Courneen | courne001jos | 1903 | 5/1-9/11 | Fall River Indians | New England League | , | |
| Ernie Courtney | courtn001edw | 1903 | New York | American League | New York, NY | ||
| Ernie Courtney | courtn001edw | 1903 | Detroit | American League | Detroit, MI | ||
| George? Courtney | courtn013--- | 1903 | 5/7-5/1 | Meriden Silverites | Connecticut League | , | |
| Jim Courtright | courtr000jim | 1903 | Pittsburg Coal Diggers | Missouri Valley League | , | ||
| Jack Coveney | covene001joh | 1903 | 5/1-9/12 | Nashua | New England League | , | |
| Jack Coveney | covene001joh | 1903 | 9/19-9/27 | St. Louis | National League | St. Louis, MO | |
| George Cowan | cowan-001geo | 1903 | 9/7-9/9 | Newark Sailors | Eastern League | , | |
| Cox | 1903 | Pendleton | Inland Empire League | , | |||
| Bob Cox | cox---004rob | 1903 | 5/30-8/8 | Umpire | Southern Association | , | |
| Chesty Cox | cox---002eug | 1903 | no g. | Louisville Colonels | American Association | , | |
| Chesty Cox | cox---002eug | 1903 | 5/2 | Toledo Mud Hens | American Association | , | |
| Chesty Cox | cox---002eug | 1903 | 6/19- | 35 g. | Duluth Cardinals | Northern League | , |
| Chesty Cox | cox---002eug | 1903 | 6/30- | Superior Longshoremen | Northern League | , | |
| Chesty Cox | cox---002eug | 1903 | Brandon | Manitoba | , | ||
| Chesty Cox | cox---002eug | 1903 | +8/26-9/8 | Grand Forks Forkers | Northern League | , | |
| James Cox | cox---001jam | 1903 | Bowdoin College | College | , | ||
| James Cox | cox---001jam | 1903 | 6/24-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Joseph Cox | cox---001jos | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| L. Cox | cox---000l-- | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Frank Coyle | coyle-001fra | 1903 | 4/26- | Paris Parasites/Waco Steers | Texas League | Paris/Waco, | |
| Frank Coyle | coyle-001fra | 1903 | -8/25 | Corsicana Oil Citys | Texas League | , | |
| Ernest Crabill | crabil001ern | 1903 | 5/6-8/6 | Columbus Senators | American Association | , | |
| Ernest Crabill | crabil001ern | 1903 | 8/13-9/19 | Birmingham Barons | Southern Association | , | |
| Leech Cracraft | cracra000lee | 1903 | 3/17- | U. of Virginia | College | , | |
| Leech Cracraft | cracra000lee | 1903 | 9/16 | Wheeling Stogies | Central League | , | |
| Edward Craig | craig-001edw | 1903 | Tacoma Tigers | Pacific National League | , | ||
| Edward Craig | craig-001edw | 1903 | 5/2-7/30 | Fort Scott Giants | Missouri Valley League | , | |
| Edward Craig | craig-001edw | 1903 | 8/6-8/24 | Dallas Giants | Texas League | , | |
| Edward Craig | craig-001edw | 1903 | 9/11-9/12 | Fort Scott Giants | Missouri Valley League | , | |
| Edward Craig | craig-001edw | 1903 | 9/17 | Kansas City Blue Stockings | Western League | , | |
| Edward Craig | craig-001edw | 1903 | 9/25 | Fort Scott Giants | Missouri Valley League | , | |
| Harry Craig | 1903 | Wilmerding PA | Independent | , | |||
| Doc Crandall | cranda002jam | 1903 | Frankfort IN | Independent | , | ||
| Newton Crandall | 1903 | Winnipeg Maroons | Northern League | , | |||
| John Crane | crane-001joh | 1903 | 5/18 | Lowell Tigers | New England League | , | |
| James Crangle | crangl001jam | 1903 | Dixon College | College | , | ||
| James Crangle | crangl001jam | 1903 | 5/9-5/25 | Terre Haute Hottentots | Central League | , | |
| James Crangle | crangl001jam | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| James Crangle | crangl001jam | 1903 | 13 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | |
| Charles Crate | crate-001cha | 1903 | 9/23 | Baltimore Orioles | Eastern League | , | |
| Gavvy Cravath | cravat001cli | 1903 | Los Angeles Angels | Pacific Coast League | , | ||
| James Cravens | craven002jam | 1903 | 5/3-9/21 | Fort Scott Giants | Missouri Valley League | , | |
| Al Crawley | crawle001alg | 1903 | preseason | Huntsville | Tennessee-Alabama League | , | |
| David Creagan | creaga002dav | 1903 | Hudson Marines | Hudson River League | , | ||
| John Creagh | creagh000joh | 1903 | +7/9+ | Selma YMCA | Alabama-Georgia League | , | |
| John Creagh | creagh000joh | 1903 | +8/3+ | Greensboro AL | Independent | , | |
| Robert Creek | creek-000bob | 1903 | Hartford City IN | Independent | , | ||
| Robert Creek | creek-000bob | 1903 | 7/25-8/30 | Evansville River Rats | Central League | , | |
| Robert Creek | creek-000bob | 1903 | +9/14+ | Hartford City IN | Independent | , | |
| Creekman | creekm000--- | 1903 | 4 g. | Montgomery Black Sox | Interstate League | , | |
| Creighton | creigh000--- | 1903 | 5/22 | Omaha Indians | Western League | , | |
| Creighton | creigh000--- | 1903 | 9/7-9/8 | Omaha Indians | Western League | , | |
| Harold Cribbins | cribbi001har | 1903 | , | ||||
| Frank Crippen | crippe001fra | 1903 | 5/19-6/11+ | Red Oak Blue Indians | Southwest Iowa League | , | |
| Frank Crippen | crippe001fra | 1903 | 6/26-9/8 | Duluth Cardinals | Northern League | , | |
| Pat Crisham | crisha002pat | 1903 | 4/30-9/26 | Providence Grays | Eastern League | , | |
| Harry Criss | 1903 | 7/13-9/16 | Umpire | Central League | , | ||
| Charles Crist | crist-000cha | 1903 | +7/22+ | Great Falls MT | Independent | , | |
| Bill Cristall | crista001wil | 1903 | 5/5-9/20 | Toledo Mud Hens | American Association | , | |
| Davey Crockett | crocke001dan | 1903 | 115 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Cro Cro Croco | croco-000--- | 1903 | +7/11-7/24 | Minden | Central Nebraska League | , | |
| Harry Croft | croft-001hen | 1903 | 5/8-9/20 | Binghamton Bingoes | New York State League | , | |
| Fred Crolius | croliu001fre | 1903 | , | ||||
| George Croll | croll-001geo | 1903 | San Francisco Seals | Pacific Coast League | , | ||
| George Croll | croll-001geo | 1903 | Sacramento Senators | Pacific Coast League | , | ||
| George Croll | croll-001geo | 1903 | Oakland Oaks | Pacific Coast League | , | ||
| Lyle Cromley | cromle001lyl | 1903 | 8/28-9/7 | Indianapolis Indians | American Association | , | |
| Cronin | cronin021--- | 1903 | 7/3 | Troy Trojans | New York State League | , | |
| Arthur Cronin | cronin000art | 1903 | 7/24-8/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Jack Cronin | cronin001joh | 1903 | 20 g. | New York | National League | New York, NY | |
| Thomas Crooks | crooks002tho | 1903 | 9/26 | Baltimore Orioles | Eastern League | , | |
| Frank Cross | cross-001fra | 1903 | 5/2-9/15 | Evansville River Rats | Central League | , | |
| Frank Cross | cross-001fra | 1903 | Umpire | Central League | , | ||
| Lave Cross | cross-001laf | 1903 | 137 g. | Philadelphia | American League | Philadelphia, PA | |
| Lem Cross | cross-001lem | 1903 | 5/2-9/12 | Lowell Tigers | New England League | , | |
| Leo Crossin | crossi000leo | 1903 | Fordham College | College | , | ||
| Leo Crossin | crossi000leo | 1903 | 5/13 | Newark Sailors | Eastern League | , | |
| Dan Crotty | crotty001dan | 1903 | Umpire | Oklahoma League | , | ||
| Francis Crotty | crotty000fra | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Francis Crotty | crotty000fra | 1903 | +6/24-9/20 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |
| Edward Crowder | crowde001ned | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Harry Crowe | crowe-000har | 1903 | Pittsburg Coal Diggers | Missouri Valley League | , | ||
| Dick Crozier | crozie001j-- | 1903 | 5/25-9/20 | Atlanta Crackers | Southern Association | , | |
| Charles Crum | crum--001cha | 1903 | 5/2-8/7 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Charles Crum | crum--001cha | 1903 | 8/8-9/17 | Kansas City Blue Stockings | Western League | , | |
| Walter Crum | crum--001wal | 1903 | 4/28-6/29 | St. Joseph Saints | Western League | , | |
| Walter Crum | crum--001wal | 1903 | 51 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Joseph Cuddy | cuddy-001joh | 1903 | JC-West Side AC | Independent | , | ||
| Jim Cudworth | cudwor001jim | 1903 | 6/6-6/30 | Umpire | New England League | , | |
| Cullen | 1903 | 8/31-9/12 | Umpire | Connecticut League | , | ||
| A. B. Culton | culton001--- | 1903 | 5/10-9/6 | Centralia Midgets | Southwest Washington League | , | |
| Cummings | cummin027--- | 1903 | 6/12- | Red Cloud | Central Nebraska League | , | |
| Bob Cummings | cummin000bob | 1903 | 6/14- | Selma YMCA | Alabama-Georgia League | , | |
| Bert Cunningham | cunnin001ell | 1903 | U. Virginia | College | , | ||
| Bert Cunningham | cunnin001ell | 1903 | 4/22-9/20 | Umpire | American Association | , | |
| George Cuppy | cuppy-001geo | 1903 | +9/14+ | Logansport IN | Independent | , | |
| Curley | curley003--- | 1903 | 7/22 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Edward Curley | curley000edd | 1903 | 9/11 | Lawrence Colts | New England League | , | |
| Parker Curley | curley001par | 1903 | Holy Cross Col. | College | , | ||
| Parker Curley | curley001par | 1903 | 5/16-6/13 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Walter Curley | curley001doc | 1903 | , | ||||
| Curren | curren005--- | 1903 | 8/14 | Norwich Reds | Connecticut League | , | |
| Clarence Currie | currie001cla | 1903 | St. Louis | National League | St. Louis, MO | ||
| Clarence Currie | currie001cla | 1903 | Chicago | National League | Chicago, IL | ||
| Jack Curry | curry-001joh | 1903 | Sault Ste. Marie | Independent | , | ||
| Jack Curry | curry-001joh | 1903 | +9/22+ | Flint-Mills | Independent | , | |
| John Curtan | curtan000jac | 1903 | St. Marys | College | , | ||
| John Curtan | curtan000jac | 1903 | 6/19-6/23 | Leavenworth White Sox | Missouri Valley League | , | |
| Cliff Curtis | curtis001cli | 1903 | 5/1-9/15 | Fort Wayne Railroaders | Central League | , | |
| Clyde Curtis | curtis004--- | 1903 | 5/10-9/6 | Olympia Senators | Southwest Washington League | , | |
| Clyde Curtis | curtis004--- | 1903 | +7/7+ | Tacoma Tigers | Pacific National League | , | |
| Don Curtis | curtis002don | 1903 | Dallas Giants | Texas League | , | ||
| Gene Curtis | curtis002eug | 1903 | Bethany College | College | , | ||
| Gene Curtis | curtis002eug | 1903 | 5/25-9/16 | Wheeling Stogies | Central League | , | |
| Gene Curtis | curtis002eug | 1903 | 9/3-9/17 | Des Moines Undertakers | Western League | , | |
| Gene Curtis | curtis002eug | 1903 | 9/21-9/26 | Pittsburgh | National League | Pittsburgh, PA | |
| Harry Curtis | curtis001har | 1903 | 5/2-5/25 | Haverhill Hustlers | New England League | , | |
| Joe Curtis | curtis001jos | 1903 | 6/30-7/1 | Baltimore Orioles | Eastern League | , | |
| Joe Curtis | curtis001jos | 1903 | 8/7-8/22 | Baltimore Orioles | Eastern League | , | |
| Paul Curtis | curtis002eug | 1903 | 5/1-6/6 | Colorado Springs Millionaires | Western League | , | |
| Paul Curtis | curtis001pau | 1903 | 6/16-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Tommy Curvin | curvin000tom | 1903 | Peen Yan NY | Independent | , | ||
| Ed Cusack | 1903 | 5/2-6/2 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | ||
| Ed Cusack | 1903 | Umpire | Missouri Valley League | , | |||
| Stephen Cusack | 1903 | 5/30-7/31 | Umpire | Northern League | , | ||
| Stephen Cusack | 1903 | Umpire | Central League | , | |||
| Harvey Cushman | cushma001har | 1903 | 4/30-9/17 | Des Moines Undertakers | Western League | , | |
| Win Cutter | cutter002win | 1903 | Sacramento Senators | Pacific Coast League | , | ||
| Win Cutter | cutter002win | 1903 | San Francisco Seals | Pacific Coast League | , | ||
| William Dahlquist | dahlqu001wil | 1903 | 4/30-6/30 | Wheeling Stogies | Central League | , | |
| William Dahlquist | dahlqu001wil | 1903 | 7/28-8/3 | Wheeling Stogies | Central League | , | |
| William Dahlquist | dahlqu001wil | 1903 | +9/11+ | 15 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , |
| Con Daily | daily-001con | 1903 | Hudson River League | , | |||
| Daley | daley-015--- | 1903 | 5/22-5/25 | Springfield Ponies | Connecticut League | , | |
| Con Daley | 1903 | Ossining/Catskill | Hudson River League | Ossining, | |||
| Eddie Daley | daley-001edw | 1903 | 5/8-9/20 | Syracuse Stars | New York State League | , | |
| James Daley | daley-002jam | 1903 | 54 g. | Kingston Colonials | Hudson River League | , | |
| George Dalrymple | dalrym001geo | 1903 | 4/14- | 33 g. | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, |
| George Dalrymple | dalrym001geo | 1903 | Boise ID | Independent | , | ||
| George Dalrymple | dalrym001geo | 1903 | 7/4-7/15 | Grand Forks Forkers | Northern League | , | |
| William Dalton | dalton001wil | 1903 | 5/7-5/30 | New London Whalers | Connecticut League | , | |
| William Dalton | dalton001wil | 1903 | 6/3 | Norwich Reds | Connecticut League | , | |
| Bert Daly | daly--001alb | 1903 | 5/9-7/25 | Hartford Senators | Connecticut League | , | |
| Bert Daly | daly--001alb | 1903 | 8/7-9/5 | Philadelphia | American League | Philadelphia, PA | |
| Tom Daly | daly--002tho | 1903 | 43 g. | Chicago | American League | Chicago, IL | |
| Tom Daly | daly--002tho | 1903 | 80 g. | Cincinnati | National League | Cincinnati, OH | |
| Bill Dammann | damman001bil | 1903 | 4/14- | 49 g. | Spokane Indians | Pacific National League | , |
| Danforth | 1903 | +5/25+ | Pendleton | Inland Empire League | , | ||
| Daniels | daniel045--- | 1903 | +4/10+ | U. Alabama | College | , | |
| Daniels | daniel045--- | 1903 | 6/12-7/16+ | Talladega Tigers | Alabama-Georgia League | , | |
| Daniels | daniel045--- | 1903 | Anniston AL | Independent | , | ||
| Daniels | daniel045--- | 1903 | 8/20-9/8+ | Pulaski | Tennessee-Alabama League | , | |
| Daniels | daniel037--- | 1903 | 5/20-6/16 | Superior Longshoremen | Northern League | , | |
| Daniels | daniel040--- | 1903 | 5/5 | Wheeling Stogies | Central League | , | |
| Daniels | daniel040--- | 1903 | 6/27 | Wheeling Stogies | Central League | , | |
| Jesse Daniels | daniel002jes | 1903 | 5/4-5/17 | South Bend Greens | Central League | , | |
| Harry Dannehower | danneh001j-- | 1903 | 5/9-9/20 | New Orleans Pelicans | Southern Association | , | |
| James Darnell | 1903 | Umpire | Illinois-Indiana-Iowa League | , | |||
| James Darnell | 1903 | 7/16-7/26 | Umpire | Western League | , | ||
| Walter Dashwood | dashwo001wal | 1903 | Petaluma | California State League | , | ||
| Walter Dashwood | dashwo001wal | 1903 | Oakland Reliance | California State League | , | ||
| Dan Daub | daub--002dan | 1903 | 8/26-9/16 | Umpire | Central League | , | |
| Augustus Daum | daum--001aug | 1903 | 5/2-9/12 | Nashua | New England League | , | |
| Homer Davidson | davids001hom | 1903-07 | U. Pennsylvania | College | , | ||
| Davis | davis-145--- | 1903 | 7/22-7/23 | Toledo Mud Hens | American Association | , | |
| Davis | 1903 | Univ. of Vermont | College | , | |||
| Davis | 1903 | Burlington VT | Independent | , | |||
| Davis | davis-013wil | 1903 | 5/20-5/22 | Duluth Cardinals | Northern League | , | |
| Davis | davis-147--- | 1903 | 7/31-8/11 | Haverhill Hustlers | New England League | , | |
| Ben Davis | davis-001ben | 1903 | -7/16 | Fort Dodge | Iowa League | , | |
| Ben Davis | davis-001ben | 1903 | Webster City | Independent | , | ||
| Ben Davis | davis-001ben | 1903 | +8/1-8/2+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| C. D. Davis | davis-000cd- | 1903 | 5/21-6/3 | Superior Longshoremen | Northern League | , | |
| Elmer Davis | davis-002elm | 1903 | 108 g. | Altoona PA | Independent | , | |
| George Davis | davis-015geo | 1903 | New York | National League | New York, NY | ||
| Gerald Davis | davis-004ger | 1903 | 6/23-7/10 | Iola Gaslighters | Missouri Valley League | , | |
| Gerald Davis | davis-004ger | 1903 | 7/20-8/7 | Sedalia Goldbugs | Missouri Valley League | , | |
| Gerald Davis | davis-004ger | 1903 | 9/15-9/17 | Sedalia Goldbugs | Missouri Valley League | , | |
| H. R. Davis | davis-000hr- | 1903 | Univ. of Maine | College | , | ||
| H. R. Davis | davis-000hr- | 1903 | 5/8-5/19 | Albany Senators | New York State League | , | |
| Ira Davis | davis-008j-- | 1903 | 4/14-10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Port/SLC, | |
| Kilmer Davis | 1903 | Altoona PA | Independent | , | |||
| Lefty Davis | davis-001alf | 1903 | 104 g. | New York | American League | New York, NY | |
| Si Davis | davis-000si- | 1903 | Salem | Willamette Valley | Salem, OR | ||
| Walt Davis | davis-003wal | 1903 | 43 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Walt Davis | davis-003wal | 1903 | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | ||
| William Davis | davis-013wil | 1903 | 4/23-5/7 | St. Paul Saints | American Association | , | |
| William Davis | davis-013wil | 1903 | 6/27 | Milwaukee Brewers | American Association | , | |
| William Davis | davis-013wil | 1903 | 7/5 | Minneapolis Millers | American Association | , | |
| William Davis | davis-013wil | 1903 | 7/21 | St. Paul Saints | American Association | , | |
| William Davis | davis-030wil | 1903 | Wissahicken | Independent | , | ||
| William Davis | davis-030wil | 1903 | Oxford PA | Independent | , | ||
| Nicholas Daviscourt | davisc000nic | 1903 | +6/17-7/4 | Albany | Oregon State League | , | |
| Lee Dawkins | dawkin001lev | 1903 | 430 ab | Pine Bluff Lumbermen | Cotton States League | , | |
| Day | day---018--- | 1903 | 8/7 | Concord Marines | New England League | , | |
| Billy Day | day---002bil | 1903 | 6/12,9/5-9/7 | Springfield Midgets | Missouri Valley League | , | |
| Billy Day | day---002bil | 1903 | 6/13 | Iola Gaslighters | Missouri Valley League | , | |
| Henry Day | 1903 | , | |||||
| Henry Daye | daye--001hen | 1903 | 4/25-6/2 | Houston Buffaloes | South Texas League | , | |
| James De Pree | depree000jim | 1903 | Holland MI | Independent | , | ||
| Leroy Deakin | deakin000ler | 1903 | 5/24-5/26 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Snake Deal | deal--002joh | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| Dean | dean--002--- | 1903 | 5/24-6/21 | Centralia Midgets | Southwest Washington League | , | |
| Beach Dean | dean--001bea | 1903 | Oakland Heeseman | California State League | , | ||
| Homer Dean | dean--000hom | 1903 | Whatcom WA | Independent | , | ||
| Charlie DeArmond | dearmo002cha | 1903 | 4/30-9/15 | Terre Haute Hottentots | Central League | , | |
| Charlie DeArmond | dearmo002cha | 1903 | 9/19-9/27 | Cincinnati | National League | Cincinnati, OH | |
| Walter Deaver | deaver001wal | 1903 | 5/4 | Birmingham Barons | Southern Association | , | |
| Walter Deaver | deaver001wal | 1903 | 7/19-8/24 | New Orleans Pelicans | Southern Association | , | |
| Archie DeBaker | debake001art | 1903 | +7/5+ | Muskegon MI | Independent | , | |
| Albert Decker | decker001alb | 1903 | Piqua OH | Independent | , | ||
| Albert Decker | decker001alb | 1903 | 6/2-9/16 | Terre Haute Hottentots | Central League | , | |
| Alonzo DeCosta | decost001a-- | 1903 | Gainsville FL | Independent | , | ||
| Alonzo DeCosta | decost001a-- | 1903 | +8/14-8/17+ | Gadsden AL | Independent | , | |
| Alonzo DeCosta | decost001a-- | 1903 | 8/24-9/12 | Pulaski | Tennessee-Alabama League | , | |
| Deeder | deeder000--- | 1903 | +6/24-7/11+ | Giltner | Central Nebraska League | , | |
| Hughey Deehan | 1903 | 7/5-7/25 | Umpire | Central League | , | ||
| Jimmy Deering | 1903 | Red Oak Blue Indians | Southwest Iowa League | , | |||
| John Deering | deerin001joh | 1903 | 10 g. | Detroit | American League | Detroit, MI | |
| John Deering | deerin001joh | 1903 | 9 g. | New York | American League | New York, NY | |
| DeForest | defore000--- | 1903 | 7/28 | Hartford Senators | Connecticut League | , | |
| Rube DeGroff | degrof001edw | 1903 | 16 g. | Kingston Colonials | Hudson River League | , | |
| Rube DeGroff | degrof001edw | 1903 | Saugerties | Hudson River League | , | ||
| Otto Deininger | deinin001ott | 1903 | 5/5-9/12 | Haverhill Hustlers | New England League | , | |
| Henry Deisel | deisel001c-- | 1903 | 4/14- | 137 g. | Spokane Indians | Pacific National League | , |
| Jacob Deisel | deisel001jac | 1903 | 5/8- | 19 g. | San Francisco Pirates | Pacific National League | , |
| Pat Deisel | deisel001edw | 1903 | -9/19 | 2 g. | Cincinnati | National League | Cincinnati, OH |
| Charles Deiters | deiter001cha | 1903 | 4/30-9/16 | Wheeling Stogies | Central League | , | |
| Frank Delahanty | delaha001fra | 1903 | 5/12-9/20 | Syracuse Stars | New York State League | , | |
| Jim Delahanty | delaha001jam | 1903 | 90 g. | Little Rock Travelers | Southern Association | , | |
| Joe Delahanty | delaha001jos | 1903 | 4/30-6/19 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Joe Delahanty | delaha001jos | 1903 | 6/22-7/14,8/7 | New Orleans Pelicans | Southern Association | , | |
| Joe Delahanty | delaha001jos | 1903 | 8/24-9/20 | Memphis Egyptians | Southern Association | , | |
| Tom Delahanty | delaha001tho | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Delaney | delane019--- | 1903 | 6/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Charles Delaney | delane000cha | 1903 | GrFalls-Mavericks | Independent | , | ||
| Mickey Delaney | delane002mic | 1903 | 5/8-7/6 | Springfield Ponies | Connecticut League | , | |
| Mickey Delaney | delane002mic | 1903 | 7/11-9/1 | Norwich Reds | Connecticut League | , | |
| Thomas Delaney | delane001tho | 1903 | San Francisco | California State League | , | ||
| William Dell | dell--001wil | 1903 | +5/12+ | Butte High School | High School | , | |
| Phil Deller | deller001phi | 1903 | 19 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Phil Deller | deller001phi | 1903 | +8/25-9/8 | Grand Forks Forkers | Northern League | , | |
| Del Delmas | delmas001ber | 1903 | 201 g. | San Francisco Seals | Pacific Coast League | , | |
| Chas. Demmitt | 1903-04 | Rose-Hulman | College | , | |||
| Charles Demong | demong001cha | 1903 | Syracuse Univ. | College | , | ||
| Charles Demong | demong001cha | 1903 | 6/18-9/20 | Ilion Typewriters | New York State League | , | |
| Gene DeMontreville | demont001eug | 1903 | Washington | American League | Washington, DC | ||
| Gene DeMontreville | demont001eug | 1903 | 6/22-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Gene DeMontreville | demont001eug | 1903 | 7/20-8/10 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Lee DeMontreville | demont002leo | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| Lee DeMontreville | demont002leo | 1903 | -7/1 | Haverhill Hustlers | New England League | , | |
| Lee DeMontreville | demont002leo | 1903 | 7/10-9/26 | St. Louis | National League | St. Louis, MO | |
| Charles DeMoss | demoss001cha | 1903 | +6/20+ | Niles OH | Independent | , | |
| St. Julian Dendy | 1903-04 | Clemson Col | College | , | |||
| Dennis | 1903-06 | Univ. of Iowa | College | , | |||
| Bert Dennis | dennis002ber | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| Denny | 1903 | Altoona PA | Independent | , | |||
| Densmore | densmo002--- | 1903 | 8/30 | Fort Scott Giants | Missouri Valley League | , | |
| James Denton | denton010--- | 1903 | +5/15-5/22+ | U. of Tennessee | College | , | |
| Owen Depew | depew-001o-- | 1903 | 5/21-8/6 | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Owen Depew | depew-001o-- | 1903 | 8/8+ | Clarinda | Independent | , | |
| William Derby | derby-001--- | 1903 | 5/4-9/7 | Lowell Tigers | New England League | , | |
| Derrick | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |||
| O. Derrick | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |||
| Billy Derwin | derwin001wil | 1903 | +5/12+ | Reading PA | Independent | , | |
| Billy Derwin | derwin001wil | 1903 | 5/29-6/1 | Hartford Senators | Connecticut League | , | |
| Sam Deskin | deskin001sam | 1903 | 8/11-8/13 | Beaumont Oil Gushers | South Texas League | , | |
| Ed Desonia | 1903 | 8/22-9/13 | Pine Bluff Lumbermen | Cotton States League | , | ||
| William Devereaux | devere001wil | 1903 | 163 g. | Oakland Oaks | Pacific Coast League | , | |
| Devine | devine010--- | 1903 | 8/20 | Rochester Bronchos | Eastern League | , | |
| Art Devlin | devlin001art | 1903 | 4/30-9/19 | Newark Sailors | Eastern League | , | |
| Nick Devoe | devoe-001nic | 1903 | 5/8-9/17 | Troy Trojans | New York State League | , | |
| Arthur DeWeese | dewees001--- | 1903 | +6/17+ | Kingman KS | Independent | , | |
| James Dewey | dewey-001jam | 1903 | 5/18-8/26 | Fort Worth Panthers | Texas League | , | |
| James Dewey | dewey-001jam | 1903 | Stockton | California State League | , | ||
| Charlie Dexter | dexter002cha | 1903 | -9/27 | 123 g. | Boston | National League | Boston, MA |
| Ed Dickens | dicken000ned | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Ed Dickens | dicken000ned | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Ed Dickens | dicken000ned | 1903 | 8/12-8/25 | Huntsville | Tennessee-Alabama League | , | |
| Ed Dickens | dicken000ned | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Emerson Dickerson | dicker001eme | 1903 | Ohio State U. | College | , | ||
| Emerson Dickerson | dicker001eme | 1903 | Big Rapids MI | Independent | , | ||
| Guy Dickey | dickey001guy | 1903 | 113 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Charles Diebold | 1903 | +5/16+ | Rochester PA | Independent | , | ||
| Charles Diebold | 1903 | +7/30+ | Pittsburgh A. C. | Independent | , | ||
| Ernie Diehl | diehl-001ern | 1903 | 5/31 | Pittsburgh | National League | Pittsburgh, PA | |
| Harry Diehl | diehl-001har | 1903 | 4/30-9/11 | St. Joseph Saints | Western League | , | |
| Diehlman | diehlm000--- | 1903 | 6/6 | Colorado Springs Millionaires | Western League | , | |
| Diggins | diggin000--- | 1903 | 7/21-7/24 | Bridgeport Orators | Connecticut League | , | |
| William Diggins | diggin001wil | 1903 | 5/5-8/27 | Providence Grays | Eastern League | , | |
| Milton Dillard | dillar001mil | 1903 | 2+ g. | Pulaski | Tennessee-Alabama League | , | |
| Pat Dillard | dillar002pat | 1903 | 4/30-9/24 | Newark Sailors | Eastern League | , | |
| Ed Dillon | dillon001edw | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Ed Dillon | dillon001edw | 1903 | 8/3-8/31 | Houston Buffaloes | South Texas League | , | |
| Frank Dillon | dillon001fra | 1903 | 190 g. | Los Angeles Angels | Pacific Coast League | , | |
| Jack Dillon | dillon002joh | 1903 | 5/2-9/25 | Jersey City Skeeters | Eastern League | , | |
| George Disch | disch-001geo | 1903 | Racine WI | Independent | , | ||
| George Disch | disch-001geo | 1903 | Duluth Cardinals | Northern League | , | ||
| William Disch | disch-001wil | 1903 | 4/25-8/18 | Fort Worth Panthers | Texas League | , | |
| Clyde Dixon | dixon-001cly | 1903 | 8/28-8/29 | Galveston Sand Crabs | South Texas League | , | |
| Doane | 1903 | +6/22-7/24 | McCook | Central Nebraska League | , | ||
| James Doar | doar--000jam | 1903 | 6/5- | 9 g. | Duluth Cardinals | Northern League | , |
| John Dobbs | dobbs-001joh | 1903 | Chicago | National League | Chicago, IL | ||
| John Dobbs | dobbs-001joh | 1903 | Brooklyn | National League | Brooklyn, NY | ||
| Fred Doe | doe---002fre | 1903 | Brockton/New Bedford Whalers | New England League | Brockton, | ||
| Fred Doe | doe---002fre | 1903 | 9/4 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| William Doerr | doerr-001wil | 1903 | 5/2-5/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| William Doerr | doerr-001wil | 1903 | +7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Webb City, | |
| Frank Doherty | dohert001fra | 1903 | Fargo | Northern League | , | ||
| James Doherty | dohert004jam | 1903 | Williamsport | Independent | , | ||
| James Doherty | dohert004jam | 1903 | Wilmington | Independent | , | ||
| James Doherty | dohert004jam | 1903 | 99 g. | Altoona PA | Independent | , | |
| Mike Doherty | dohert001mic | 1903 | 5/8-9/20 | Albany Senators | New York State League | , | |
| Dolan | 1903 | 6/29-7/25 | Umpire | Connecticut League | , | ||
| Cozy Dolan | dolan-001pat | 1903 | Chicago | American League | Chicago, IL | ||
| Cozy Dolan | dolan-001pat | 1903 | Cincinnati | National League | Cincinnati, OH | ||
| Joe Dolan | dolan-001jos | 1903 | 91 g. | Seattle Siwashes | Pacific Coast League | , | |
| Joe Dolan | dolan-001jos | 1903 | 4/30-7/6 | Omaha Indians | Western League | , | |
| John Dolan | dolan-002joh | 1903 | 4/27-8/31 | Little Rock Travelers | Southern Association | , | |
| Fred Doll | doll--001fre | 1903 | 14 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Fred Doll | doll--001fre | 1903 | 39 g. | Superior Longshoremen | Northern League | , | |
| Dennis Donahue | donahu001den | 1903 | Addison NY | Independent | , | ||
| Dennis Donahue | donahu001den | 1903 | Elmira NY | Independent | , | ||
| Jiggs Donahue | donahu001joh | 1903 | 4/22-9/21 | Milwaukee Brewers | American Association | , | |
| Matthew Donahue | donahu001mat | 1903 | 52 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | |
| Pat Donahue | donahu003pat | 1903 | 5/10-9/20 | Utica Pent-Ups | New York State League | , | |
| Red Donahue | donahu001fra | 1903 | St. Louis | American League | St. Louis, MO | ||
| Red Donahue | donahu001fra | 1903 | Cleveland | American League | Cleveland, OH | ||
| She Donahue | donahu002cha | 1903 | 4/14- | 140 g. | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, |
| She Donahue | donahu002cha | 1903 | -10.4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Thomas Donahue | donahu001tho | 1903 | 6/27-8/30 | St. Joseph Saints | Western League | , | |
| Thomas Donahue | donahu002tho | 1903 | 5/27-6/11+ | Butte Miners | Pacific National League | , | |
| Thomas Donahue | donahu002tho | 1903 | 5/30-5/31 | Helena Senators | Pacific National League | , | |
| Thomas Donahue | donahu003tho | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Edward Donnelly | donnel001edw | 1903 | Kingston Colonials | Hudson River League | , | ||
| Em Donnelly | donnel001em- | 1903 | 5/7-5/30 | Norwich Reds | Connecticut League | , | |
| Em Donnelly | donnel001em- | 1903 | 6/6-6/13 | Bridgeport Orators | Connecticut League | , | |
| Frank Donnelly | donnel002fra | 1903 | 115 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Frank Donnelly | donnel004fra | 1903 | -7/20 | 33 g. | Kingston Colonials | Hudson River League | , |
| August Donohoo | 1903 | 6/12-7/3+ | Talladega Tigers | Alabama-Georgia League | , | ||
| Donovan | 1903 | 5/7-6/14 | Dayton | Inland Empire League | , | ||
| Donovan | donova064--- | 1903 | 5/24-5/25 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Donovan | donova064--- | 1903 | +6/8-6/9 | Leavenworth White Sox | Missouri Valley League | , | |
| Donovan | donova054--- | 1903 | 9/15 | Rochester Bronchos | Eastern League | , | |
| Bill Donovan | donova004wil | 1903-18 | Detroit | American League | Detroit, MI | ||
| Fred Donovan | donova002fre | 1903 | 108 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| J. L. Donovan | donova046--- | 1903 | 6/7-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Jerry Donovan | donova001jer | 1903 | +7/6-8/18+ | Williamsport PA | Independent | , | |
| Martin Donovan | donova002mar | 1903 | 5/13-6/2 | Norwich Reds | Connecticut League | , | |
| Martin Donovan | donova002mar | 1903 | 6/25-7/6 | New London Whalers | Connecticut League | , | |
| Martin Donovan | donova002mar | 1903 | 7/28-8/1 | Bridgeport Orators | Connecticut League | , | |
| Martin Donovan | donova002mar | 1903 | 8/8-9/12 | Springfield Ponies | Connecticut League | , | |
| Mike Donovan | donova002mic | 1903 | 5/1-5/6 | Haverhill Hustlers | New England League | , | |
| Mike Donovan | donova002mic | 1903 | 7/7- | Hartford Senators | Connecticut League | , | |
| Mike Donovan | donova002mic | 1903 | -9/12 | Springfield Ponies | Connecticut League | , | |
| Tom Donovan | donova002tho | 1903 | 114 g. | Utica Pent-Ups | New York State League | , | |
| Mickey Doolin | doolan001mic | 1903 | 4/20-9/26 | Jersey City Skeeters | Eastern League | , | |
| Frank Doran | doran-001fra | 1903 | 5/5-5/7 | Haverhill Hustlers | New England League | , | |
| Jimmy Doran | doran-008--- | 1903 | 6/1-6/4 | New Haven Blues | Connecticut League | , | |
| Tom Doran | doran-002tho | 1903 | 5/5-9/17 | Colorado Springs Millionaires | Western League | , | |
| Connie Doremus | doremu001con | 1903 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | ||
| William Dorgan | dorgan001wil | 1903 | 9/3-9/11 | Denver Grizzlies | Western League | , | |
| Johnny Dorman | dorman001joh | 1903 | Georgetown | College | , | ||
| Johnny Dorman | dorman001joh | 1903 | -7/15 | Fort Dodge | Iowa League | , | |
| Johnny Dorman | dorman001joh | 1903 | Webster City | Independent | , | ||
| Johnny Dorman | dorman001joh | 1903 | +8/11-8/19 | Seattle Chinooks | Pacific National League | , | |
| Peter Dorn | dorn--001pet | 1903 | 8/17-9/4 | Toledo Mud Hens | American Association | , | |
| Gus Dorner | dorner001aug | 1903 | Cleveland | American League | Cleveland, OH | ||
| Gus Dorner | dorner001aug | 1903 | 7/28-9/18 | Columbus Senators | American Association | , | |
| Luke Dorsey | dorsey001luk | 1903 | 7/18- | Haverhill Hustlers | New England League | , | |
| Luke Dorsey | dorsey001luk | 1903 | -7/28 | Fall River Indians | New England League | , | |
| Jack Doscher | dosche001joh | 1903 | Fordham Col. | College | , | ||
| Jack Doscher | dosche001joh | 1903 | 6/27 | Troy Trojans | New York State League | , | |
| Jack Doscher | dosche001joh | 1903 | 7/2 | Chicago | National League | Chicago, IL | |
| Jack Doscher | dosche001joh | 1903 | 3 g. | Brooklyn | National League | Brooklyn, NY | |
| Jack Doscher | dosche001joh | 1903 | 9/22-9/25 | Baltimore Orioles | Eastern League | , | |
| Doskin | doskin000--- | 1903 | 8/11-8/13 | Beaumont Oil Gushers | South Texas League | , | |
| John Doubles | double001j-- | 1903 | Kane PA | Independent | , | ||
| Dougherty | doughe003--- | 1903 | Oakland Reliance | California State League | , | ||
| Dougherty | doughe011--- | 1903 | Stockton | California State League | , | ||
| Patsy Dougherty | doughe002pat | 1903 | 139 g. | Boston | American League | Boston, MA | |
| Tom Dougherty | doughe001tho | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Tom Dougherty | doughe001tho | 1903 | Atlanta Crackers | Southern Association | , | ||
| Archibald Douglas | dougla000hug | 1903 | U. of Tennessee | College | , | ||
| Archibald Douglas | dougla000hug | 1903 | 6/30-8/7+ | Anniston Invincibles | Alabama-Georgia League | , | |
| Archibald Douglas | dougla000hug | 1903 | +8/18-8/19+ | Decatur | Tennessee-Alabama League | , | |
| Archibald Douglas | dougla000hug | 1903 | 6/30-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Archibald Douglas | dougla000hug | 1903 | +8/8-9/12 | Decatur | Tennessee-Alabama League | , | |
| Klondike Douglass | dougla004wil | 1903 | 105 g. | Philadelphia | National League | Philadelphia, PA | |
| John Doup | doup--001joh | 1903 | +10/4+ | Loui.-Reccius | Independent | , | |
| Dove | dove--003--- | 1903 | 8/1-8/17 | Binghamton Bingoes | New York State League | , | |
| George Dovey | dovey-001geo | 1903 | Tacony | Independent | , | ||
| George Dovey | dovey-001geo | 1903 | +10/12 | Camden NJ | Independent | , | |
| Tommy Dowd | dowd--001tho | 1903 | 4/30-7/10 | Baltimore Orioles | Eastern League | , | |
| Tommy Dowd | dowd--001tho | 1903 | 8/4-9/12 | Nashua | New England League | , | |
| Roy Dowers | dowers001roy | 1903 | Baker City OR | Independent | , | ||
| Roy Dowers | dowers001roy | 1903 | 6/12-7/24 | Giltner | Central Nebraska League | , | |
| Joe Dowie | dowie-001joe | 1903 | 5/1-8/31 | Houston Buffaloes | South Texas League | , | |
| P. Dowing | dowing000p-- | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Dowling | dowlin012--- | 1903 | 6/27 | Springfield Ponies | Connecticut League | , | |
| Dowling | dowlin013--- | 1903 | 8/4 | Hartford Senators | Connecticut League | , | |
| Joseph Dowling | dowlin001jos | 1903 | 5/7-6/16 | Norwich Reds | Connecticut League | , | |
| Patrick Dowling | dowlin001pat | 1903 | Altoona PA | Independent | , | ||
| Pete Dowling | dowlin001hen | 1903 | 4/14- | 52 g. | Butte Miners | Pacific National League | , |
| Frederick Downer | 1903 | 9/7-9/12 | Umpire | New York State League | , | ||
| Downey | downey013--- | 1903 | 7/7 | Nashua | New England League | , | |
| Jim Downey | downey002jam | 1903 | 4/30-9/24 | Toronto Maple Leafs | Eastern League | , | |
| Thomas Downey | downey002tho | 1903 | Salem | Willamette Valley | Salem, OR | ||
| Thomas Downey | downey002tho | 1903 | 8/9-9/8 | Centralia Midgets | Southwest Washington League | , | |
| Tom Downey | downey003tho | 1903 | 5/16-9/12 | Bridgeport Orators | Connecticut League | , | |
| Albert Downing | 1903 | +5/19+ | Lexington KY | Independent | , | ||
| Red Downs | downs-001jer | 1903 | 5/2-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Doyle | doyle-001cha | 1903 | 8/15 | Little Rock Travelers | Southern Association | , | |
| Charles Doyle | doyle-002cha | 1903 | 197 g. | Sacramento Senators | Pacific Coast League | , | |
| Charles Doyle | doyle-001cha | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Charles Doyle | doyle-001cha | 1903 | 8/15 | Little Rock Travelers | Southern Association | , | |
| Charles Doyle | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | |||
| Jack Doyle | doyle-002joh | 1903 | 139 g. | Brooklyn | National League | Brooklyn, NY | |
| Slow Joe Doyle | doyle-001jud | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| William Doyle | doyle-008wil | 1903 | 4/26-8/22 | Dallas Giants | Texas League | , | |
| Herbert Drake | drake-002har | 1903 | +6/26+ | Coudersport PA | Independent | , | |
| Jack Drennan | drenna001kir | 1903 | 4/14- | 144 g. | Seattle Chinooks | Pacific National League | , |
| Mike Drennan | drenna001mik | 1903 | Wissahickon PA | Independent | , | ||
| Bob Dresser | dresse001rob | 1903 | St. Albans | , | |||
| Drew | 1903 | Charleston WV | , | ||||
| Bobby Drew | drew--001edw | 1903 | 5/7-8/8 | Meriden Silverites | Connecticut League | , | |
| Bobby Drew | drew--001edw | 1903 | 8/11-9/12 | New London Whalers | Connecticut League | , | |
| Henry Drew | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |||
| Frank Drill | drill-000fra | 1903 | no g. | Brooklyn | National League | Brooklyn, NY | |
| Frank Drill | drill-000fra | 1903 | 6/25-7/4 | Crookston Crooks | Northern League | , | |
| Lew Drill | drill-001lew | 1903 | 51 g. | Washington | American League | Washington, DC | |
| Vianello Drinkwater | drinkw001via | 1903 | 21 g. | Los Angeles Angels | Pacific Coast League | , | |
| Jimmie Driscoll | drisco002jam | 1903 | 5/2-7/8 | Joplin Miners | Missouri Valley League | , | |
| Jimmie Driscoll | drisco002jam | 1903 | 7/14-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Jimmy Driscoll | drisco004jam | 1903 | 5/23 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| John Driscoll | drisco007joh | 1903 | 6/19 | Toledo Mud Hens | American Association | , | |
| James Drohan | drohan001jam | 1903 | 23 g. | Seattle Siwashes | Pacific Coast League | , | |
| Carl Druhot | druhot001car | 1903 | +5/14-6/14 | Colfax | Inland Empire League | , | |
| Carl Druhot | druhot001car | 1903 | 7/4 | Roseburg | Willamette Valley | Roseburg, OR | |
| Ferd Drumm | drumm-001fer | 1903 | Zanesville OH | ProtAssn | , | ||
| Tom Drummy | drummy001tom | 1903 | 5/15-5/16 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Bob Drury | drury-001rob | 1903 | no g. | Indianapolis Indians | American Association | , | |
| Bob Drury | drury-001rob | 1903 | 4/25-6/18 | New Orleans Pelicans | Southern Association | , | |
| Bob Drury | drury-001rob | 1903 | 10 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Bob Drury | drury-001rob | 1903 | 7/26-9/20 | Binghamton Bingoes | New York State League | , | |
| Pat Duff | duff--001pat | 1903 | Manhattan College | College | , | ||
| Pat Duff | duff--001pat | 1903 | Jersey City Skeeters | Eastern League | , | ||
| Thomas Duff | duff--001tho | 1903 | Manchester | New England League | , | ||
| William Duff | duff--000wil | 1903 | 6 g. | Mobile | Interstate League | , | |
| Hugh Duffy | duffy-001hug | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| John Duffy | duffy-003joh | 1903 | 4/27-9/20 | Birmingham Barons | Southern Association | , | |
| Dugan | dugan-017--- | 1903 | 7/16-7/23 | Anniston Invincibles | Alabama-Georgia League | , | |
| Tom Dugan | dugan-001tho | 1903 | 4/25-5/23 | Corsicana Oil Citys | Texas League | , | |
| Tom Dugan | dugan-001tho | 1903 | 5/31-8/30 | Galveston Sand Crabs | South Texas League | , | |
| Daniel Duggan | duggan001dan | 1903 | Holy Cross | College | , | ||
| Daniel Duggan | duggan001dan | 1903 | 7/10-9/25 | Providence Grays | Eastern League | , | |
| Ed Duggan | duggan002ed- | 1903 | 9/1 | Indianapolis Indians | American Association | , | |
| John Duggan | duggan001joh | 1903-05 | Franklin College | College | , | ||
| Thomas Duke | duke--001tho | 1903 | 8/11-8/20 | Birmingham Barons | Southern Association | , | |
| Harry Dunbar | dunbar000har | 1903-04 | Indiana St Normal | College | , | ||
| Gus Dundon | dundon001aug | 1903 | 4/30-8/6 | Denver Grizzlies | Western League | , | |
| Sam Dungan | dungan001sam | 1903 | 4/22-7/4 | Milwaukee Brewers | American Association | , | |
| Sam Dungan | dungan001sam | 1903 | 7/8-9/20 | Memphis Egyptians | Southern Association | , | |
| John Dunham | 1903 | Oklahoma City | Independent | , | |||
| Wiley Dunham | dunham001hen | 1903 | 5/6-5/16 | Milwaukee Brewers | American Association | , | |
| Wiley Dunham | dunham001hen | 1903 | 5/25-5/30 | Indianapolis Indians | American Association | , | |
| Wiley Dunham | dunham001hen | 1903 | 6/14-7/18 | Memphis Egyptians | Southern Association | , | |
| Davy Dunkle | dunkle001edw | 1903 | Chicago | American League | Chicago, IL | ||
| Davy Dunkle | dunkle001edw | 1903 | Washington | American League | Washington, DC | ||
| Ernest Dunlap | dunlap001e-- | 1903 | +4/9+ | Southern Univ. | College | , | |
| Ernest Dunlap | dunlap001e-- | 1903 | 7/9-7/17 | Talladega Tigers | Alabama-Georgia League | , | |
| George Dunlap | dunlap008--- | 1903 | +5/6+ | Coe University | College | , | |
| Paul Dunlap | 1903 | Purdue Univ. | College | , | |||
| Bill Dunleavy | dunlea001wil | 1903 | 4/22-9/21 | Milwaukee Brewers | American Association | , | |
| Jack Dunleavy | dunlea001joh | 1903 | 5/30- | 61 g. | St. Louis | National League | St. Louis, MO |
| Dunn | 1903 | +5/25+ | Pendleton | Inland Empire League | , | ||
| Bert Dunn | dunn--003ber | 1903 | 6/6-8/16 | Helena Senators | Pacific National League | , | |
| Bert? Dunn | dunn--055--- | 1903 | 5/3-5/26 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Jack Dunn | dunn--005joh | 1903 | 78 g. | New York | National League | New York, NY | |
| William Dunn | dunn--001wil | 1903 | 122 g. | Syracuse Stars | New York State League | , | |
| Frank Dupee | dupee-001fra | 1903 | 5/5-5/15 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Frank Dupee | dupee-001fra | 1903 | 6/11- | Lawrence Colts | New England League | , | |
| Frank Dupee | dupee-001fra | 1903 | -9/2 | Haverhill Hustlers | New England League | , | |
| George Duquette | duquet001geo | 1903 | 5/12 | Syracuse Stars | New York State League | , | |
| George Duquette | duquet001geo | 1903 | Brandon | Manitoba | , | ||
| George Duquette | duquet001geo | 1903 | 7/25 | Winnipeg Maroons | Northern League | , | |
| George Duquette | duquet001geo | 1903 | no g. | Detroit | American League | Detroit, MI | |
| Art Durall | durall001a-- | 1903 | 5/20-6/15 | Superior Longshoremen | Northern League | , | |
| Dan Durand | durand001h-- | 1903 | 5/2-5/27 | Springfield Midgets | Missouri Valley League | , | |
| Dan Durand | durand001h-- | 1903 | 5/29-6/19 | Sedalia Goldbugs | Missouri Valley League | , | |
| Dan Durand | durand001h-- | 1903 | 6/21-7/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Dan Durand | durand001h-- | 1903 | Weir City Browns | Independent | , | ||
| Dan Durand | durand001h-- | 1903 | 8/21 | Joplin Miners | Missouri Valley League | , | |
| Dan Durand | durand001h-- | 1903 | 9/13-9/15 | Umpire | Missouri Valley League | , | |
| Dan Durand | durand001h-- | 1903 | 9/18-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Durfee | durfee000--- | 1903 | Corning NY | Independent | , | ||
| Bull Durham | durham001lou | 1903 | 5/12-6/5 | New London Whalers | Connecticut League | , | |
| Bull Durham | durham001lou | 1903 | 7/6-7/10 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| James Durham | durham003jam | 1903 | 4/23-9/19 | 57 g. | Kansas City Cowboys | American Association | , |
| James Durham | durham003jam | 1903 | Indianapolis Indians | American Association | , | ||
| Earl Durkee | durkee001ear | 1903 | 4/28-9/17 | Des Moines Undertakers | Western League | , | |
| Robert Durnbaugh | durnba001rob | 1903 | 5/11-6/20 | Meriden Silverites | Connecticut League | , | |
| Robert Durnbaugh | durnba001rob | 1903 | 7/4-9/10 | Holyoke Paperweights | Connecticut League | , | |
| Ike Durrett | durret001isa | 1903 | 4/27-5/8 | Montgomery Black Sox | Southern Association | , | |
| Ike Durrett | durret001isa | 1903 | 1 g. | Seattle Siwashes | Pacific Coast League | , | |
| Ike Durrett | durret001isa | 1903 | +5/20+ | 114 g. | Spokane Indians | Pacific National League | , |
| Alfred Duvall | duvall001alf | 1903 | 47 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Alfred Duvall | duvall001alf | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | ||
| Dwyer | dwyer-020--- | 1903 | 14 g. | Anderson/Grand Rapids Orphans | Central League | Anderson/GR, | |
| Dwyer | dwyer-031--- | 1903 | 6/16 | Galveston Sand Crabs | South Texas League | , | |
| Eddie Dwyer | dwyer-020--- | 1903 | 6/10-6/26 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Eddie? Dwyer | dwyer-015--- | 1903 | 8/2- | 16 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , |
| Edward Dwyer | dwyer-000edd | 1903 | Forsyth MT | Independent | , | ||
| Arthur Dye | dye---009--- | 1903 | 5/10-9/6 | Olympia Senators | Southwest Washington League | , | |
| Billy Dyer | dyer--001wil | 1903 | Woonsocket | , | |||
| Billy Dyer | dyer--001wil | 1903 | Jersey City Skeeters | Eastern League | , | ||
| Jimmy Dygert | dygert001jam | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Jimmy Dygert | dygert001jam | 1903 | 6/16-7/9 | Utica Pent-Ups | New York State League | , | |
| Pete Eagan | eagan-001pat | 1903 | 5/8-9/20 | Albany Senators | New York State League | , | |
| Truck Eagan | eagan-001cha | 1903 | 206 g. | Sacramento Senators | Pacific Coast League | , | |
| Bobby Eager | eager-001rob | 1903 | 28 g. | Los Angeles Angels | Pacific Coast League | , | |
| Howard Earl | earl--002how | 1903 | 5/8-9/20 | Ilion Typewriters | New York State League | , | |
| Billy Earle | earle-001bil | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Carl Easley | easley001--- | 1903 | 5/10-7/5 | Centralia Midgets | Southwest Washington League | , | |
| Carl Easley | easley001--- | 1903 | 7/12-7/26 | Aberdeen Pippins | Southwest Washington League | , | |
| Carl Easley | easley001--- | 1903 | 8/2-9/6 | Centralia Midgets | Southwest Washington League | , | |
| Mal Eason | eason-001mal | 1903 | 6/23-7/11 | Louisville Colonels | American Association | , | |
| Mal Eason | eason-001mal | 1903 | 7 g. | Detroit | American League | Detroit, MI | |
| Claude East | east--002wal | 1903 | 5/2-6/2 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Walter East | east--002wal | 1903 | 6/4-8/7 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Walter East | east--002wal | 1903 | Univ. of Pittsburgh | College | , | ||
| Chris Eastman | eastma001chr | 1903 | 51 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| DeWorth Easton | easton001dew | 1903 | 5/2-7/28 | Marion Oilworkers | Central League | , | |
| Eaton | eaton-006--- | 1903 | 7/11-7/16 | Dayton Veterans | Central League | , | |
| Eaton | eaton-006--- | 1903 | Muncie IN | Independent | , | ||
| Eaton | eaton-003--- | 1903 | 6 g. | Olympia Senators | Southwest Washington League | , | |
| George Eaton | eaton-001geo | 1903 | 5/5-9/12 | Concord Marines | New England League | , | |
| Hi Ebright | ebrigh001hi- | 1903 | Milwaukee Brewers | American Association | , | ||
| Hi Ebright | ebrigh001hi- | 1903 | 7/27-9/20 | Umpire | Southern Association | , | |
| Mills Ebright | ebrigh001a-- | 1903 | Baker Univ. | College | , | ||
| Mills Ebright | ebrigh001a-- | 1903 | 5/27-6/11 | St. Joseph Saints | Western League | , | |
| Mills Ebright | ebrigh001a-- | 1903 | 60 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springfield, | |
| Andrew Ecklund | ecklun001and | 1903 | Helena MT | Independent | , | ||
| David Eddington | 1903 | U. of Alabama | College | , | |||
| Edington | edingt004--- | 1903 | +5/7+ | Univ. Alabama | College | , | |
| Bob Edmondson | edmond002rob | 1903 | 6/25-8/31 | Houston Buffaloes | South Texas League | , | |
| Otis Edmondson | edmond001oti | 1903 | +7/15-8/14 | Decatur AL | Independent | , | |
| Otis Edmondson | edmond001oti | 1903 | 2+ g. | Decatur | Tennessee-Alabama League | , | |
| David Edmunds | edmund002dav | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Robert Edmunds | 1903 | 9/5 | Manchester | New England League | , | ||
| Mays Edmundson | edmund001may | 1903 | preseason | Toledo Mud Hens | American Association | , | |
| Mays Edmundson | edmund001may | 1903 | Homestead PA | Independent | , | ||
| Dave Edwards | edward007dav | 1903 | +5/14-6/14 | Dayton | Inland Empire League | , | |
| Dave Edwards | edward007dav | 1903 | 7/5-9/6 | Centralia Midgets | Southwest Washington League | , | |
| Joseph Edwards | edward001gil | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Ralph Edwards | edward003ral | 1903 | 8/14-9/9 | Fall River Indians | New England League | , | |
| W. A. Edwards | edward002w-- | 1903 | 5/20-9/8 | Crookston Crooks | Northern League | , | |
| Harry Eells | eells-001har | 1903 | Oakland Heeseman | California State League | , | ||
| Harry Eells | eells-001har | 1903 | 7/2-9/25 | Joplin Miners | Missouri Valley League | , | |
| Harry Eells | eells-001har | 1903 | 5 g. | Oakland Oaks | Pacific Coast League | , | |
| Harry Eells | eells-001har | 1903 | 1 g. | Seattle Siwashes | Pacific Coast League | , | |
| Eels | eels--000--- | 1903 | 6/14 | Olympia Senators | Southwest Washington League | , | |
| Dick Egan | egan--001ric | 1903-08 | Fordham College | College | , | ||
| Dick Egan | egan--001ric | 1903 | 3 g. | San Francisco Seals | Pacific Coast League | , | |
| Dick Egan | egan--001ric | 1903 | 7/- | Helena Senators | Pacific National League | , | |
| Dick Egan | egan--001ric | 1903 | 7/- | Los Angeles | Pacific National League | , | |
| Jack Egan | egan--001rip | 1903 | Little Rock Travelers | Southern Association | , | ||
| Jack Egan | egan--001rip | 1903 | 8/20- | 8 g. | MLB Umpire | American League | , |
| Ned Egan | egan--001edw | 1903 | 5/20-9/8 | Winnipeg Maroons | Northern League | , | |
| Wish Egan | egan--001alo | 1903 | 4/22-9/20 | Louisville Colonels | American Association | , | |
| Friedrich Eggers | eggers001fre | 1903 | Concordia College | College | , | ||
| Friedrich Eggers | eggers001fre | 1903 | FW-Shamrocks | Independent | , | ||
| Friedrich Eggers | eggers001fre | 1903 | 6/28-6/29 | Terre Haute Hottentots | Central League | , | |
| Friedrich Eggers | eggers001fre | 1903 | Tell City IN | Independent | , | ||
| Friedrich Eggers | eggers001fre | 1903 | +8/23+ | Elkhart IN | Independent | , | |
| Charles Eggert | eggert001cha | 1903 | 5/26-7/9 | Dayton Veterans | Central League | , | |
| Ray Egner | egner-001ray | 1903 | +8/19+ | Tren-YMCA | Independent | , | |
| George Ehle | ehle--001geo | 1903 | 5/10-6/7 | Lebanon IL | Independent | , | |
| George Ehle | ehle--001geo | 1903 | +7/6 | Joplin Miners | Missouri Valley League | , | |
| George Ehle | ehle--001geo | 1903 | 8/22-9/27 | Joplin Miners | Missouri Valley League | , | |
| Fred Ehman | ehman-001fre | 1903 | Canton OH | Amateur | , | ||
| Red Ehret | ehret-001phi | 1903 | 4/26-6/29 | Memphis Egyptians | Southern Association | , | |
| Charles Eichberger | eichbe001cha | 1903 | Addison NY | Independent | , | ||
| G. P. Eichenbarger | 1903 | 5/21-9/16 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Harry Eichler | eichle001har | 1903 | 5/1-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Harry Eichler | eichle001har | 1903 | 5/30-6/3 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Harry Eichler | eichle001har | 1903 | Sidney OH | Independent | , | ||
| Aaron Eldridge | eldrid000aar | 1903 | 5/30-6/7 | Beaumont Oil Gushers | South Texas League | , | |
| Aaron Eldridge | eldrid000aar | 1903 | Umpire | Texas League | , | ||
| Frank Eley | eley--001fra | 1903 | Hudson Marines | Hudson River League | , | ||
| Charles Ellinor | 1903 | +8/1+ | Hartford AR | Independent | , | ||
| Claude Elliott | elliot001cla | 1903 | 4/22-9/20 | Milwaukee Brewers | American Association | , | |
| Ben Ellis | ellis-003ben | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Eli Ellis | ellis-001eli | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Elsdon | 1903 | 6/4-6/14 | Walla Walla | Inland Empire League | , | ||
| Charles Elsey | elsey-001cha | 1903 | 4/14-4/24+ | Spokane Indians | Pacific National League | , | |
| Charles Elsey | elsey-001cha | 1903 | +5/13-8/16 | San Francisco Pirates | Pacific National League | , | |
| Charles Elsey | elsey-001cha | 1903 | 36 g. | Portland Browns | Pacific Coast League | , | |
| Charles Elston | elston001cur | 1903 | Zanesville OH | Independent | , | ||
| Bones Ely | ely---001wil | 1903 | 4/14-4/26 | San Francisco Pirates | Pacific National League | , | |
| Bones Ely | ely---001wil | 1903 | ?-11/29 | Portland Browns | Pacific Coast League | , | |
| Frederick Ely | 1903-06 | , | |||||
| Jack Ely | ely---001joh | 1903 | 4/28-5/10 | Montgomery Black Sox | Southern Association | , | |
| Jack Ely | ely---001joh | 1903 | 5/19-9/20 | Atlanta Crackers | Southern Association | , | |
| Thomas Embleton | 1903 | Burlington | Northern New York League | , | |||
| Emminger | emming000--- | 1903 | 7/25-7/26 | Dayton Veterans | Central League | , | |
| George Engel | engel-002geo | 1903 | +4/11-7/11+ | Portland Browns | Pacific Coast League | , | |
| George Engel | engel-002geo | 1903 | +8/14-9/4+ | Seattle Chinooks | Pacific National League | , | |
| George Engel | engel-002geo | 1903 | 9/20-10/3 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Arthur Engle | engle-001art | 1903 | 4/29 | Nashville Volunteers | Southern Association | , | |
| Arthur Engle | engle-001art | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Edward Erickson | ericks002edw | 1903 | Delano MN | Independent | , | ||
| Albert Erle | erle--002alb | 1903 | San Jose | California State League | , | ||
| Joe Erwin | erwin-001--- | 1903 | 5/2-5/18 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Joe Erwin | erwin-001--- | 1903 | 6/17-7/1+ | Leavenworth White Sox | Missouri Valley League | , | |
| Joseph Erwin | erwin-001jos | 1903 | 6/6-6/7 | Houston Buffaloes | South Texas League | , | |
| Joseph Erwin | erwin-001jos | 1903 | 6/8-8/26 | Beaumont Oil Gushers | South Texas League | , | |
| Joseph Erwin | erwin-001jos | 1903 | 8/29-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Joseph Essenter | 1903 | Broo.-Ridgewood | Independent | , | |||
| Bill Essick | essick002wil | 1903 | 7/22-8/3 | Fort Wayne Railroaders | Central League | , | |
| Bill Essick | essick002wil | 1903 | +8/16+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Elmer Essler | essler001elm | 1903 | 65 g. | Natchez Indians | Cotton States League | , | |
| John Eubank | eubank001joh | 1903 | 94 ab | Greenville Grays | Cotton States League | , | |
| Jacob Eul | eul---001jac | 1903 | 25 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Jacob Eul | eul---001jac | 1903 | Decatur Commodores | Illinois-Indiana-Iowa League | , | ||
| Frank Eustace | eustac003fra | 1903 | 5/1-9/12 | Concord Marines | New England League | , | |
| Evans | evans-046--- | 1903 | York PA | Independent | , | ||
| James Evans | evans-000wl- | 1903 | ?-9/27 | Ossining/Catskill | Hudson River League | Catskill, | |
| Roy Evans | evans-001roy | 1903 | 15 g. | Brooklyn | National League | Brooklyn, NY | |
| Roy Evans | evans-001roy | 1903 | -8/4 | 7 g. | St. Louis | American League | St. Louis, MO |
| Roy Evans | evans-001roy | 1903 | 8/16-8/28 | Sedalia Goldbugs | Missouri Valley League | , | |
| W. L. Evans | evans-000wl- | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| Will Evans | evans-004wil | 1903 | 4/25-8/9 | Memphis Egyptians | Southern Association | , | |
| Will Evans | evans-004wil | 1903 | 8/10-9/20 | New Orleans Pelicans | Southern Association | , | |
| William Evans | 1903 | Umpire | Pennsylvania Ohio League | , | |||
| William Everett | everet002wil | 1903 | 82 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Everhard | everha002--- | 1903 | 6/30-7/8 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Frank Everhart | everha001fra | 1903 | 7/23-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Bill Everitt | everet001wil | 1903 | 4/28-9/17 | Colorado Springs Millionaires | Western League | , | |
| Jack Evers | evers-001joh | 1903 | 5/2-5/13 | Rochester Bronchos | Eastern League | , | |
| Jack Evers | evers-001joh | 1903 | 5/29-7/14 | Binghamton Bingoes | New York State League | , | |
| Jack Evers | evers-001joh | 1903 | 7/31-9/20 | Albany Senators | New York State League | , | |
| Johnny Evers | evers-002joh | 1903-13 | Chicago | National League | Chicago, IL | ||
| Bert Everson | everso001a-- | 1903 | no g. | Concord Marines | New England League | , | |
| Bert Everson | everso001a-- | 1903 | Wilmington DE | Independent | , | ||
| Elwood Eyler | eyler-001elw | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Henry? Fabian | fabian001hen | 1903 | 5/30 | Dallas Giants | Texas League | , | |
| Cotton Fagan | fagan-000cot | 1903 | 4/27-4/30 | Houston Buffaloes | South Texas League | , | |
| Jim Fairbank | fairba001jam | 1903 | 5/12-9/12 | Utica Pent-Ups | New York State League | , | |
| Jim Fairbank | fairba001jam | 1903 | 9/18 - | 4 g. | Philadelphia | American League | Philadelphia, PA |
| Cy Falkenberg | falken001fre | 1903 | 4/21- | 10 g. | Pittsburgh | National League | Pittsburgh, PA |
| Cy Falkenberg | falken001fre | 1903 | 6/18-7/17 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Cy Falkenberg | falken001fre | 1903 | 7/20-7/27 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Cy Falkenberg | falken001fre | 1903 | 9/10-9/23 | Toronto Maple Leafs | Eastern League | , | |
| Fallon | fallon006--- | 1903 | Kingston Colonials | Hudson River League | , | ||
| Patrick Fallon | fallon000pat | 1903 | Hazleton PA | Independent | , | ||
| Joseph Falls | falls-001jos | 1903 | 6/25-9/1 | St. Joseph Saints | Western League | , | |
| Leonard Fanning | fannin002l-- | 1903 | 5/3-5/28 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Leonard Fanning | fannin002l-- | 1903 | 7/-8/ | La Junta CO | Independent | , | |
| Farley | 1903 | Hobart College | College | , | |||
| Andrew Farley | farley001and | 1903 | 27 g. | Kingston Colonials | Hudson River League | , | |
| W. Farley | farley000w-- | 1903 | Saugerties | Hudson River League | , | ||
| Alex Farmer | farmer001ale | 1903 | 4/30-6/3 | Providence Grays | Eastern League | , | |
| Alex Farmer | farmer001ale | 1903 | 7/15-8/1 | Utica Pent-Ups | New York State League | , | |
| Alex Farmer | farmer001ale | 1903 | 8/8-8/15 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| T. Farmer | farmer000t-- | 1903 | 3 g. | Mobile | Interstate League | , | |
| Ben Farnham | farnha001ben | 1903 | 5/7-5/15 | Hartford Senators | Connecticut League | , | |
| Farrell | farrel049--- | 1903 | 8/12-9/7 | Wheeling Stogies | Central League | , | |
| Bernard Farrell | farrel001ber | 1903 | 5/4-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Bernard Farrell | farrel001ber | 1903 | 5/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Charles Farrell | farrel005--- | 1903 | 5/19-7/12 | Sedalia Goldbugs | Missouri Valley League | , | |
| Frank Farrell | farrel002fra | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| Jack Farrell | 1903 | Helena | Arkansas State League | , | |||
| John Farrell | farrel006joh | 1903 | St. Louis | National League | St. Louis, MO | ||
| Albert Farris | farris001law | 1903 | Kentucky-Illinois-Tennessee League | , | |||
| Paul Faucett | faucet001--- | 1903 | Murfreesboro TN | Independent | , | ||
| Oliver Faulkner | faulkn001oli | 1903 | +10/12 | Wilmington DE | Independent | , | |
| Henry Faust | 1903 | Kane PA | Independent | , | |||
| Edward Fay | fay---001edw | 1903 | 93 g. | Kingston Colonials | Hudson River League | , | |
| Joe Fay | fay---001jos | 1903 | +7/8+ | 79 g. | Tacoma Tigers | Pacific National League | , |
| Joe Fay | fay---001jos | 1903 | 6/4- | Pendleton | Inland Empire League | , | |
| Owen Fay | fay---000owe | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Feeley | 1903 | 9/14-9/20 | Umpire | New York State League | , | ||
| Jim Feeney | feeney002jam | 1903 | 5/3-5/17 | Des Moines Undertakers | Western League | , | |
| Jim Feeney | feeney002jam | 1903 | StL-White Seals | Independent | , | ||
| Jim Feeney | feeney002jam | 1903 | 6/21-8/23 | Springfield Midgets | Missouri Valley League | , | |
| Joe Feeney | feeney000joe | 1903 | 6/10-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Joe Feeney | feeney000joe | 1903 | 6/23 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Joe Feeney | feeney000joe | 1903 | Canton SD | Independent | , | ||
| William Fehl | fehl--001--- | 1903 | +5/27-7/2+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Albert Felder | felder001alb | 1903 | 4/26- | Fort Worth Panthers | Texas League | , | |
| Harry Feldhaus | feldha001har | 1903 | 5/6-5/16 | Nashville Volunteers | Southern Association | , | |
| Harry Feldhaus | feldha001har | 1903 | 6/14-7/9 | Dayton Veterans | Central League | , | |
| Harry Feldhaus | feldha001har | 1903 | 7/11-9/20 | Nashville Volunteers | Southern Association | , | |
| Harry Felix | felix-001har | 1903 | 4/29 | Louisville Colonels | American Association | , | |
| George Felter | 1903 | 7/3-7/14 | Corsicana Oil Citys | Texas League | , | ||
| Matthias Fennell | fennel001mat | 1903 | Elmira NY | Independent | , | ||
| Matthias Fennell | fennel001mat | 1903 | U. of Pennsylvania | College | , | ||
| Fredrick Fenske | fenske001fre | 1903 | 5/8 | Fall River Indians | New England League | , | |
| Fredrick Fenske | fenske001fre | 1903 | 8/8 | Springfield Ponies | Connecticut League | , | |
| Cecil Ferguson | fergus002geo | 1903 | 5/7-9/16 | South Bend Greens | Central League | , | |
| Charlie Ferguson | fergus002cha | 1903 | 4/25-9/9 | St. Paul Saints | American Association | , | |
| George Ferris | ferris001geo | 1903 | 4/14- | 146 g. | Spokane Indians | Pacific National League | , |
| Cy Ferry | ferry-001alf | 1903 | 5/1-9/26 | Buffalo Bisons | Eastern League | , | |
| Ed Fertsch | fertsc001edw | 1903 | 5/8,6/2 | Jersey City Skeeters | Eastern League | , | |
| Ed Fertsch | fertsc001edw | 1903 | 6/6-9/26 | Rochester Bronchos | Eastern League | , | |
| Fetter | fetter003--- | 1903 | 4/17 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Carl Fettes | 1903 | SLC-CherryReds | Independent | , | |||
| Carl Fettes | 1903 | +6/26+ | Ogden UT | Independent | , | ||
| Carl Fettes | 1903 | Atlantic | Southwest Iowa League | , | |||
| H. Claude Fetz | fetz--002cla | 1903 | +4/+ | U. Nebraska | College | , | |
| H. Claude Fetz | fetz--002cla | 1903 | Marysville KS | Independent | , | ||
| Willy Fetzer | fetzer001wil | 1903-05 | Davidson College | College | , | ||
| George Feye | feye--001geo | 1903 | 16 g. | Duluth Cardinals | Northern League | , | |
| Field | field-002--- | 1903 | 7/10-7/25 | Hartford Senators | Connecticut League | , | |
| Fields | fields024--- | 1903 | 5/18 | Leavenworth White Sox | Missouri Valley League | , | |
| Jack Fifield | fifiel001jac | 1903 | 5/8-9/18 | Syracuse Stars | New York State League | , | |
| Jack Fillman | fillma001joh | 1903 | -5/1 | 31 g. | Oakland Oaks | Pacific Coast League | , |
| Jack Fillman | fillma001joh | 1903 | +5/17-9/27 | Joplin Miners | Missouri Valley League | , | |
| Fillmore | fillmo002--- | 1903 | +7/15+ | Winn.-Marlboros | Independent | , | |
| Fillmore | fillmo002--- | 1903 | +8/11-8/30+ | Winn.-Mets | Independent | , | |
| Fillmore | fillmo002--- | 1903 | 8/? | Winnipeg Maroons | Northern League | , | |
| Milton Fink | fink--001mil | 1903 | 5/10-9/6 | Olympia Senators | Southwest Washington League | , | |
| Billy Finn | finn--001wil | 1903 | 5/7-9/12 | New London Whalers | Connecticut League | , | |
| Mickey Finn | finn--001duk | 1903 | 4/27-9/20 | Little Rock Travelers | Southern Association | , | |
| Al. Fischer | 1903 | Battle Creek MI | , | ||||
| William Fischman | fischm001wil | 1903 | Camden NJ | Independent | , | ||
| William Fischman | fischm001wil | 1903 | 5/7-6/27 | New Haven Blues | Connecticut League | , | |
| William Fischman | fischm001wil | 1903 | 6/30-9/12 | Springfield Ponies | Connecticut League | , | |
| Leslie Fish | fish--002les | 1903 | Hudson Marines | Hudson River League | , | ||
| Fisher | fisher057--- | 1903 | 11 g. | Montgomery Black Sox | Interstate League | , | |
| Fisher | fisher061--- | 1903 | 7/30 | Evansville River Rats | Central League | , | |
| C. Fisher | fisher000c-- | 1903 | +5/21-6/14 | Walla Walla | Inland Empire League | , | |
| Charles Fisher | fisher009cha | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Chauncey Fisher | fisher005cha | 1903 | Joliet IL | Independent | Joliet IL, | ||
| E. F. Fisher | fisher000ef- | 1903 | 5/11 | Utica Pent-Ups | New York State League | , | |
| Harry Fisher | fisher004har | 1903 | 4/14-6/2+ | Tacoma Tigers | Pacific National League | , | |
| Harry Fisher | fisher004har | 1903 | 6/7 | Olympia Senators | Southwest Washington League | , | |
| Harry Fisher | fisher004har | 1903 | +6/10+ | 71 g. | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, |
| Harry Fisher | fisher004har | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| Harry Fisher | fisher006har | 1903 | 5/5-5/20 | Wheeling Stogies | Central League | , | |
| Ike Fisher | fisher001ike | 1903 | 4/27-9/4 | Nashville Volunteers | Southern Association | , | |
| Tom Fisher | fisher002tho | 1903 | 4/25-9/20 | Shreveport Giants | Southern Association | , | |
| Tom Fisher | fisher001tho | 1903 | 6/13-7/28 | Talladega Tigers | Alabama-Georgia League | , | |
| Tom Fisher | fisher001tho | 1903 | 20 g. | Decatur | Tennessee-Alabama League | , | |
| Walter Fisher | fisher001bat | 1903 | +8/21-9/12 | Columbia | Tennessee-Alabama League | , | |
| S.S. Fiske | fiske-001s-- | 1903 | 5/8-7/7 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| S.S. Fiske | fiske-001s-- | 1903 | Burlington | Northern New York League | , | ||
| Frank Fitch | fitch-002fra | 1903 | 5/31-6/1 | Helena Senators | Pacific National League | , | |
| John Fitzgerald | fitzge004joh | 1903 | 47 g. | Sacramento Senators | Pacific Coast League | , | |
| John Fitzhenry | fitzhe004--- | 1903 | Manhattan Col. | College | , | ||
| John Fitzhenry | fitzhe004--- | 1903 | Elmira-FatherMathew | Independent | , | ||
| John Fitzhenry | fitzhe004--- | 1903 | 7/11 | Rochester Bronchos | Eastern League | , | |
| John Fitzhenry | fitzhe004--- | 1903 | 7/15-7/27 | Hartford Senators | Connecticut League | , | |
| Billy Fitzmaurice | fitzma001wil | 1903 | 5/7-9/12 | New Haven Blues | Connecticut League | , | |
| Frank Fitzpatrick | fitzpa001fra | 1903 | 5/8-9/12 | Holyoke Paperweights | Connecticut League | , | |
| W. Fitzpatrick | fitzpa000w-- | 1903 | 4/28-4/30 | St. Joseph Saints | Western League | , | |
| Flaherty | flahar000--- | 1903 | 5/12 | Norwich Reds | Connecticut League | , | |
| Patsy Flaherty | flaher004pat | 1903 | 40 g. | Chicago | American League | Chicago, IL | |
| Steamer Flanagan | flanag003jam | 1903 | 4/22-5/2 | Toledo Mud Hens | American Association | , | |
| Steamer Flanagan | flanag003jam | 1903 | 7/29-8/6 | Toledo Mud Hens | American Association | , | |
| Steamer Flanagan | flanag003jam | 1903 | 8/11-9/2 | Meriden Silverites | Connecticut League | , | |
| Steamer Flanagan | flanag003jam | 1903 | 9/13-9/26 | Newark Sailors | Eastern League | , | |
| Stephen Flanagan | flanag001ste | 1903 | ?-9/12 | Lawrence Colts | New England League | , | |
| Jack Flannery | flanne001joh | 1903 | 4/14-6/16 | Helena Senators | Pacific National League | , | |
| Jack Flannery | flanne001joh | 1903 | 6/19-7/29 | Tacoma Tigers | Pacific National League | , | |
| Jack Flannery | flanne001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | ||
| Jack Flannery | flanne001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| Jack Flater | flater001joh | 1903 | 5/19-6/30 | Baltimore Orioles | Eastern League | , | |
| Jack Flater | flater001joh | 1903 | 7/14-9/19 | Albany Senators | New York State League | , | |
| Chuck Fleming | flemin002cha | 1903 | 16 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Chuck Fleming | flemin002cha | 1903 | Waterloo IA | Independent | , | ||
| Tom Fleming | flemin003tho | 1903 | 4/28-9/17 | Colorado Springs Millionaires | Western League | , | |
| Charles Flick | flick-001cha | 1903 | no g. | Indianapolis Indians | American Association | , | |
| Flint | flint-003--- | 1903 | 5/19 | Bridgeport Orators | Connecticut League | , | |
| Harry Flint | flint-000har | 1903 | 9/3-9/19 | Schenectady Frog Alleys | New York State League | , | |
| John Flood | flood-001joh | 1903 | Zanesville OH | ProtAssn | , | ||
| Tim Flood | flood-001tim | 1903 | -9/24 | 89 g. | Brooklyn | National League | Brooklyn, NY |
| Jack Flournoy | flourn001joh | 1903 | 4/22-6/25 | Toledo Mud Hens | American Association | , | |
| Jack Flournoy | flourn001joh | 1903 | 7/6-9/21 | St. Paul Saints | American Association | , | |
| Flynn | 1903 | Holy Cross | College | , | |||
| Flynn | 1903 | Claremont NH | Independent | , | |||
| Flynn | flynn-025--- | 1903 | 6/9 | Lawrence Colts | New England League | , | |
| Michael Flynn | flynn-003mic | 1903 | Clev.- | Independent | , | ||
| Mickey Flynn | flynn-006mic | 1903 | 6/13-6/27 | Springfield Ponies | Connecticut League | , | |
| Fogarty | 1903 | 8/28-9/5 | Umpire | New York State League | , | ||
| Lee Fohl | fohl--001leo | 1903 | 4/30-9/12 | Des Moines Undertakers | Western League | , | |
| Lee Fohl | fohl--001leo | 1903 | -9/27 | 4 g. | Cincinnati | National League | Cincinnati, OH |
| Foley | foley-026--- | 1903 | 7/9-7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbCity, | |
| Foley | foley-026--- | 1903 | 7/20 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Frank Foley | foley-001fra | 1903 | San Jose | California State League | , | ||
| Patrick Foley | foley-002pat | 1903 | 5/18 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Patrick Foley | foley-002pat | 1903 | 6/13-7/17 | Umpire | New England League | , | |
| Foote | foote-003--- | 1903 | Escanaha MI | Independent | , | ||
| Foote | foote-003--- | 1903 | 6/22 | Superior Longshoremen | Northern League | , | |
| Ford | ford--040--- | 1903 | 7/14 | Beaumont Oil Gushers | South Texas League | , | |
| Bud Ford | 1903 | Jacksonville FL | , | ||||
| Eddie Ford | ford--001edw | 1903 | 5/10-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Gene Ford | ford--002eug | 1903 | 4/26-9/17 | Indianapolis Indians | American Association | , | |
| Henry Ford | ford--001hen | 1903 | 5/2-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| James Ford | ford--004jam | 1903 | 4/25-5/6 | Galveston Sand Crabs | South Texas League | , | |
| Thomas Ford | ford--003tom | 1903 | Lockport NY | Independent | , | ||
| Thomas Ford | ford--003tom | 1903 | 5/27-6/8 | Albany Senators | New York State League | , | |
| Thomas Ford | ford--003tom | 1903 | Wellsville NY | Independent | , | ||
| Tim Ford | ford--001new | 1903 | Chat.-Custer | Independent | , | ||
| Tim Ford | ford--001new | 1903 | +8/3 | Decatur | , | ||
| Tim Ford | ford--001new | 1903 | 9/9 | Huntsville | Tennessee-Alabama League | , | |
| Ed Forde | forde-001--- | 1903 | 5/20-5/23 | Umpire | Northern League | , | |
| Ed Forde | forde-001--- | 1903 | 5/29 | Duluth Cardinals | Northern League | , | |
| Ed Forde | forde-001--- | 1903 | 7/8+ | Towner | Independent | , | |
| Frank Foreman | forema001fra | 1903 | 4/22-9/20 | Umpire | American Association | , | |
| John Foreman | forema001bro | 1903 | 5/4-5/3 | Evansville River Rats | Central League | , | |
| John Foreman | forema001bro | 1903 | 6/8-7/22 | Wheeling Stogies | Central League | , | |
| Foren | foren-002--- | 1903 | 5/31-6/3 | Jersey City Skeeters | Eastern League | , | |
| Carl Forkum | forkum002--- | 1903 | Penn State Univ | College | , | ||
| James Forman | forman000jim | 1903 | +4/9-4/22+ | U. of Alabama | College | , | |
| James Forman | forman000jim | 1903 | 6/12 | Anniston Invincibles | Alabama-Georgia League | , | |
| Kid Forney | forney001j-- | 1903 | Iola Gaslighters | Missouri Valley League | , | ||
| Forshaw | forsha001--- | 1903 | +5/15-8/15+ | Atla.-Olympics | Independent | , | |
| Forshaw | forsha001--- | 1903 | +7/23-8/1 | Rome Romans | Alabama-Georgia League | , | |
| Forshaw | forsha001--- | 1903 | +9/12+ | Atla.-Amateurs | Independent | , | |
| Foster | foster042--- | 1903 | 8/3-8/12 | Beaumont Oil Gushers | South Texas League | , | |
| Clarence Foster | foster001cla | 1903 | 5/7-9/12 | Bridgeport Orators | Connecticut League | , | |
| William Foster | foster003wil | 1903 | 5/20-9/8 | Superior Longshoremen | Northern League | , | |
| Jimmy Foulks | foulks001jam | 1903 | 5/20-9/8 | Fargo | Northern League | , | |
| Foulter | 1903 | Brown Univ. | College | , | |||
| Foulter | 1903 | Littleton NH | Independent | , | |||
| R. Frank Fowler | 1903 | 6/24-7/15 | Cotton States League | , | |||
| Fox | fox---001aug | 1903 | 5/10-9/20 | Troy Trojans | New York State League | , | |
| Fox | fox---003geo | 1903 | 52 g. | Albany Senators | New York State League | , | |
| Bill Fox | fox---006wil | 1903 | 4/22-9/20 | Indianapolis Indians | American Association | , | |
| Charley Fox | fox---003geo | 1903 | 4/30-6/2 | Baltimore Orioles | Eastern League | , | |
| Charley Fox | fox---003geo | 1903 | 6/9-8/11 | Albany Senators | New York State League | , | |
| Charley Fox | fox---003geo | 1903 | 8/12-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Clarence Fox | fox---001cla | 1903 | 5/2- | 109 g. | Dayton Veterans | Central League | , |
| George Fox | fox---001pad | 1903 | 4/22-9/20 | Columbus Senators | American Association | , | |
| Jack Fox | fox---004joh | 1903 | 5/11-6/2 | Troy Trojans | New York State League | , | |
| Jack Fox | fox---004joh | 1903 | 7/9-9/20 | Utica Pent-Ups | New York State League | , | |
| Jim Fox | fox---001jam | 1903 | 4/30-9/16 | Wheeling Stogies | Central League | , | |
| John Fox | fox---001joh | 1903 | 5/1-9/16 | Wheeling Stogies | Central League | , | |
| Bill Foxen | foxen-001wil | 1903-07 | St. Peter’s Col. | College | , | ||
| Bill Foxen | foxen-001wil | 1903 | Camden NJ | Independent | , | ||
| Bill Foxen | foxen-001wil | 1903 | 5/31-6/3 | Jersey City Skeeters | Eastern League | , | |
| Bill Foxen | foxen-001wil | 1903 | 5/7-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Bill Foxen | foxen-001wil | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Bill Foxen | foxen-001wil | 1903 | 9/3 | Jersey City Skeeters | Eastern League | , | |
| Leon Foy | foy---002leo | 1903 | 5/1- | 130 g. | Dayton Veterans | Central League | , |
| William Frakes | frakes000bil | 1903 | Gallatin-Butchers | Independent | , | ||
| France | france002car | 1903 | Fort Wayne Railroaders | Central League | , | ||
| Carl France | france002car | 1903 | 5/13 | Fort Wayne Railroaders | Central League | , | |
| Ike Francis | franci002isa | 1903 | 4/30-7/2 | Providence Grays | Eastern League | , | |
| Ike Francis | franci002isa | 1903 | 7/10-7/22 | Buffalo Bisons | Eastern League | , | |
| Ike Francis | franci002isa | 1903 | 110 g. | Portland Browns | Pacific Coast League | , | |
| Buck Francks | franck001cha | 1903 | 4/28-7/24 | Colorado Springs Millionaires | Western League | , | |
| Buck Francks | franck001cha | 1903 | 49 g. | Oakland Oaks | Pacific Coast League | , | |
| Charlie Frank | frank-003cha | 1903 | 4/27-9/20 | Memphis Egyptians | Southern Association | , | |
| Eddie Frank | frank-001edw | 1903 | 5/8-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Eddie Frank | frank-001edw | 1903 | 12/25 | Roch.-Navals | Rochester Indoor League | , | |
| Fred Frank | frank-003fre | 1903 | 4/25-9/17 | Little Rock Travelers | Southern Association | , | |
| George Frank | frank-001geo | 1903 | +5/23+ | Corpus Christi | Rochester Catholic | , | |
| George Frank | frank-001geo | 1903 | 9/7-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| George Frank | frank-001geo | 1903 | 12/25 | Roch.-Navals | Rochester Indoor League | , | |
| Franklin | frankl010--- | 1903 | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | ||
| R. S. Franklin | frankl000rs- | 1903 | 5/9-5/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Harry Franks | franks007--- | 1903 | +5/17-7/1+ | Cherryvale KS | Independent | , | |
| J. D. Franks | 1903 | no g. | Fort Worth Panthers | Texas League | , | ||
| Will Franks | franks003wil | 1903 | 8/27 | Nashville Volunteers | Southern Association | , | |
| Orville Frantz | frantz002--- | 1903 | Harvard Univ. | College | , | ||
| Walter Frantz | frantz001wal | 1903 | Fairmount College | College | , | ||
| Walter Frantz | frantz001wal | 1903 | Enid-Evangelists | Independent | , | ||
| Walter Frantz | frantz001wal | 1903 | 8/18-9/18 | Kansas City Cowboys | American Association | , | |
| Ralph Frary | frary-001ral | 1903 | 4/14-8/16 | Helena Senators | Pacific National League | , | |
| Ralph Frary | frary-001ral | 1903 | Spokane Indians | Pacific National League | , | ||
| Dotty Freck | freck-001cha | 1903 | 5/22-6/9 | Fort Wayne Railroaders | Central League | , | |
| Dotty Freck | freck-001cha | 1903 | 7/8-7/12 | Columbus Senators | American Association | , | |
| Frederick | freder010--- | 1903 | 1 g. | Mobile | Interstate League | , | |
| Freeman | freema027--- | 1903 | 5/23-6/14+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Freeman | freema027--- | 1903 | 6/25-8/21+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Freeman | freema031--- | 1903 | 9/18-9/21 | St. Paul Saints | American Association | , | |
| Buck Freeman | freema003joh | 1903 | 141 g. | Boston | American League | Boston, MA | |
| Ed Freeman | freema001edw | 1903 | 5/29-9/8 | Crookston Crooks | Northern League | , | |
| James Freeman | freema004jam | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Jerry Freeman | freema001fra | 1903 | 49 g. | Portland Browns | Pacific Coast League | , | |
| Jerry Freeman | freema001fra | 1903 | 4/17- | 141 g. | Seattle Chinooks | Pacific National League | , |
| Louis Freeman | freema001l-- | 1903 | +6/24-7/28 | Duluth Cardinals | Northern League | , | |
| Harry Freese | freese001har | 1903 | 5/21-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Harry Freese | freese001har | 1903 | 6/23-8/21+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Tony Fremer | fremer001ant | 1903 | 5/21-6/20 | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Tony Fremer | fremer001ant | 1903 | 6/23-8/2+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Tom French | french000tom | 1903 | 6/3,8/15 | Fargo | Northern League | , | |
| Win French | french001win | 1903 | 4/26-6/24 | Memphis Egyptians | Southern Association | , | |
| Win French | french001win | 1903 | 6/26-9/16 | New Orleans Pelicans | Southern Association | , | |
| Frank Frey | frye--001t-- | 1903 | preseason | Indianapolis Indians | American Association | , | |
| Frank Frey | frye--001t-- | 1903 | 6/12-6/14 | Terre Haute Hottentots | Central League | , | |
| Frank Frey | frye--001t-- | 1903 | 7/15-7/26 | Evansville River Rats | Central League | , | |
| Frank Frey | frye--001t-- | 1903 | 7/27-8/14 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Frank Frey | frye--001t-- | 1903 | 8/20-9/16 | Marion Oilworkers | Central League | , | |
| Ernest Frick | frick-001jam | 1903 | no g. | Kansas City Cowboys | American Association | , | |
| Ernest Frick | frick-001jam | 1903 | 5/2-5/22+ | Iola Gaslighters | Missouri Valley League | , | |
| Ernest Frick | frick-001jam | 1903 | Ellsworth KS | Independent | , | ||
| Hon Fricken | fricke001ant | 1903 | 5/12-6/2 | Umpire | Connecticut League | , | |
| Bill Friel | friel-001wil | 1903 | 97 g. | St. Louis | American League | St. Louis, MO | |
| Danny Friend | friend002dan | 1903 | 5/2-9/17 | Peoria Distillers | Western League | , | |
| Lentz Friend | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Charlie Frisbee | frisbe001cha | 1903 | 4/30-6/26 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Charlie Frisbee | frisbe001cha | 1903 | 6/29-7/31 | New Orleans Pelicans | Southern Association | , | |
| Emil Frisk | frisk-001joh | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Charlie Fritz | fritz-001cha | 1903 | Montgomery Black Sox | Interstate League | , | ||
| Charlie Fritz | fritz-001cha | 1903 | Brewton | Interstate League | , | ||
| Charlie Fritz | fritz-001cha | 1903 | 6/16-6/18 | Memphis Egyptians | Southern Association | , | |
| Charlie Fritz | fritz-001cha | 1903 | Greenville Grays | Cotton States League | , | ||
| Emile Fritz | fritz-001emi | 1903 | Montgomery Black Sox | Interstate League | , | ||
| Emile Fritz | fritz-001emi | 1903 | Brewton | Interstate League | , | ||
| Emile Fritz | fritz-001emi | 1903 | Greenville Grays | Cotton States League | , | ||
| Emile Fritz | fritz-001emi | 1903 | 7/16-9/20 | Memphis Egyptians | Southern Association | , | |
| Edward Frome | from--002edw | 1903 | 216 ab | Natchez Indians | Cotton States League | , | |
| Jack Frost | frost-001joh | 1903 | Natchez Indians | Cotton States League | , | ||
| Frank Frye | 1903 | Marion Oilworkers | Central League | , | |||
| William Frye | frye--001wil | 1903 | , | ||||
| Jesse Frysinger | frysin001jes | 1903 | Harrisburg PA | Independent | , | ||
| Pearly Fugler | fugler000pea | 1903 | Mississippi State | College | , | ||
| Fuller | fuller028--- | 1903 | 5/4-5/6 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Fuller | fuller013--- | 1903 | Memp.-Chickasawa | Independent | , | ||
| Fuller | fuller013--- | 1903 | 7/25- | Huntsville | Tennessee-Alabama League | , | |
| Andrew Fuller | 1903 | Fargo | Northern League | , | |||
| Billy Fuller | fuller002wil | 1903 | 79 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Charles Fuller | fuller003cha | 1903 | 5/1-6/27 | Baltimore Orioles | Eastern League | , | |
| Charles Fuller | fuller003cha | 1903 | 7/6-8/8 | Rochester Bronchos | Eastern League | , | |
| Charles Fuller | fuller003cha | 1903 | 8/13-9/25 | Toronto Maple Leafs | Eastern League | , | |
| Windsor Fulmer | fulmer001win | 1903 | Ogden UT | Independent | , | ||
| Windsor Fulmer | fulmer001win | 1903 | 7/30- | Atlantic | Southwest Iowa League | , | |
| Jake Funkhouser | funkho001jak | 1903 | Elkhart IN | Independent | , | ||
| John Furlong | furlon001joh | 1903 | Eastern Michigan | College | , | ||
| John Furlong | furlon001joh | 1903 | 6/5-6/8 | Haverhill Hustlers | New England League | , | |
| John Gabriel | gabrie002joh | 1903 | no g. | Brooklyn | National League | Brooklyn, NY | |
| John Gabriel | gabrie002joh | 1903 | 5/8-5/19 | Ilion Typewriters | New York State League | , | |
| John Gabriel | gabrie002joh | 1903 | 5/24 | Albany Senators | New York State League | , | |
| Gaetje | 1903 | Purdue Univ. | College | , | |||
| Gaetje | 1903 | FtWa Nationals | Independent | , | |||
| Roy Gage | gage--000roy | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Robert Gaines | gaines000bob | 1903 | Minden | Central Nebraska League | , | ||
| Robert Gaines | gaines000bob | 1903 | McCook NE | Independent | , | ||
| Joseph Galaski | galask001jos | 1903 | Omaha Indians | Western League | , | ||
| Gale | gale--002--- | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Gale | gale--002--- | 1903 | +6/5-7/15+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Galentine | galent000--- | 1903 | +6/24-7/6+ | Giltner | Central Nebraska League | , | |
| Eddie Gallagher | gallag001edd | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| Marty Gallagher | gallag001mar | 1903 | Hudson Marines | Hudson River League | , | ||
| Shorty Gallagher | gallag005cha | 1903 | 8/4 | New Orleans Pelicans | Southern Association | , | |
| Shorty Gallagher | gallag005cha | 1903 | 8/20-8/31 | Houston Buffaloes | South Texas League | , | |
| Shorty? Gallagher | gallag034--- | 1903 | 3 g. | Mobile | Interstate League | , | |
| Gallow | gallow001--- | 1903 | 5/10-5/24 | Aberdeen Pippins | Southwest Washington League | , | |
| Gallow | gallow001--- | 1903 | 6/21 | Centralia Midgets | Southwest Washington League | , | |
| Galpin | galpin000--- | 1903 | 5/11 | New London Whalers | Connecticut League | , | |
| Neil Gamble | gamble001mac | 1903 | U. of Tennessee | College | , | ||
| Neil Gamble | gamble001mac | 1903 | 6/13-7/31 | Anniston Invincibles | Alabama-Georgia League | , | |
| Neil Gamble | gamble001mac | 1903 | +8/12+ | Anniston AL | Independent | , | |
| Neil Gamble | gamble001mac | 1903 | -9/4 | Decatur | Tennessee-Alabama League | , | |
| Robert Gamble | gamble002rob | 1903 | U. of Tennessee | College | , | ||
| Robert Gamble | gamble002rob | 1903 | 6/24-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Robert Gamble | gamble002rob | 1903 | -9/4 | Decatur | Tennessee-Alabama League | , | |
| James Ganier | ganier001jam | 1903 | Waynesburg Col | College | , | ||
| James Ganier | ganier001jam | 1903 | 5/15-6/1 | Albany Senators | New York State League | , | |
| James Ganier | ganier001jam | 1903 | 34 g. | Kingston Colonials | Hudson River League | , | |
| Bob Ganley | ganley002rob | 1903 | 4/22-6/18 | Kansas City Cowboys | American Association | , | |
| Bob Ganley | ganley002rob | 1903 | 6/24-9/21 | Milwaukee Brewers | American Association | , | |
| Bill Gannon | gannon002wil | 1903 | 4/14- | 98 g. | Los Angeles | Pacific National League | , |
| Billy Ganss | gans--001bil | 1903 | Warren OH | Independent | , | ||
| Billy Ganss | gans--001bil | 1903 | +5/17-9/25+ | Kent OH | Independent | , | |
| Joe Ganzel | ganzel001jos | 1903 | Ionia MI | Independent | , | ||
| John Ganzel | ganzel001joh | 1903 | New York | American League | New York, NY | ||
| Earle Gardner | gardne001ear | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| Jim Gardner | gardne001jam | 1903 | 7/29 | Toronto Maple Leafs | Eastern League | , | |
| Luther Gardner | gardne001lut | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Luther Gardner | gardne001lut | 1903 | 8/21 | Clinton KY | Independent | , | |
| Joseph Garrity | garrit001jos | 1903 | Hudson Marines | Hudson River League | , | ||
| Jim Garry | garry-001jim | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Dick Garvan | 1903 | 10/19- | 20th Infantry | Army | , | ||
| John Garvan | 1903 | Hartford City | Independent | , | |||
| Garvey | garvey009--- | 1903 | 6/8-6/16+ | McCook | Central Nebraska League | , | |
| Leo Garvin | garvin001lee | 1903 | 4/30-9/17 | St. Joseph Saints | Western League | , | |
| Ned Garvin | garvin001vir | 1903 | 38 g. | Brooklyn | National League | Brooklyn, NY | |
| Gass | 1903 | 5/3-6/14 | Pendleton | Inland Empire League | , | ||
| Welcome Gaston | gaston002wel | 1903 | 5/7-6/14 | Colorado Springs Millionaires | Western League | , | |
| Welcome Gaston | gaston002wel | 1903 | 7/25-8/10 | Denver Grizzlies | Western League | , | |
| William Gaston | gaston003wil | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Hank Gastright | gastri001han | 1903 | 6/26-7/6 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Eli Gates | 1903 | Missouri Valley League | , | ||||
| Henry Gatewood | gatewo001har | 1903 | Lidgerwood | Independent | , | ||
| Henry Gatewood | gatewo001har | 1903 | 7/1-7/31+ | Superior Longshoremen | Northern League | , | |
| Henry Gatewood | gatewo001har | 1903 | +8/28-9/8 | Fargo | Northern League | , | |
| Frank Gatins | gatins001fra | 1903 | 5/5-8/23 | Milwaukee Creams | Western League | , | |
| Clyde Gay | gay---001cly | 1903 | 4/15-5/1 | Butte Miners | Pacific National League | , | |
| Gear | gear--000--- | 1903 | 8/5 | Sedalia Goldbugs | Missouri Valley League | , | |
| Dale Gear | gear--001dal | 1903 | Univ. Kansas | College | , | ||
| Dale Gear | gear--001dal | 1903 | 5/16-9/21 | Kansas City Cowboys | American Association | , | |
| Robert Geddes | geddes001rob | 1903-04 | , | ||||
| Hank Gehring | gehrin001hen | 1903 | 5/21-9/8 | Duluth Cardinals | Northern League | , | |
| Louis Gehring | gehrin000lew | 1903 | 5/1-5/6 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Louis Gehring | gehrin000lew | 1903 | 8/10-8/30 | Ilion Typewriters | New York State League | , | |
| Phil Geier | geier-001phi | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| Robert Geiselman | geisel000bob | 1903 | +12/4+ | Big Duluth | Independent | , | |
| Louis Gelb | 1903 | 5/23,7/19-7/27 | Umpire | South Texas League | , | ||
| Frank Genins | genins001c-- | 1903 | 4/28-9/17 | Omaha Indians | Western League | , | |
| Angus George | george000ang | 1903 | 7/30 | Toledo Mud Hens | American Association | , | |
| Clarence George | george001cla | 1903 | 7/15-8/17 | Corsicana Oil Citys | Texas League | , | |
| Curtis George | george002cur | 1903 | Chat.-Ft.Negley | Independent | , | ||
| Gerard | gerard002--- | 1903 | Big Duluth | Independent | , | ||
| Gerard | gerard002--- | 1903 | 6/14-6/18 | Duluth Cardinals | Northern League | , | |
| Gerard | gerard002--- | 1903 | 9/1-9/2 | Duluth Cardinals | Northern League | , | |
| Frank Gerard | gerard001fra | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Harry German | german002har | 1903 | 4/23-8/8 | Toledo Mud Hens | American Association | , | |
| G. Gerrard | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |||
| Lou Gertenrich | gerten001lou | 1903 | 1 g. | Pittsburgh | National League | Pittsburgh, PA | |
| Doc Gessler | gessle001har | 1903 | 4/22- | 29 g. | Detroit | American League | Detroit, MI |
| Doc Gessler | gessle001har | 1903 | 114 g. | Brooklyn | National League | Brooklyn, NY | |
| Charlie Gettig | gettig002cha | 1903 | 5/2-7/1 | Baltimore Orioles | Eastern League | , | |
| Charlie Gettig | gettig002cha | 1903 | 7/8-9/26 | Rochester Bronchos | Eastern League | , | |
| Tom Gettinger | gettin001tom | 1903 | Natchez Indians | Cotton States League | , | ||
| Jake Gettman | gettma001jac | 1903 | 4/30-8/19 | Buffalo Bisons | Eastern League | , | |
| John Geyer | geyer-001joh | 1903 | 5/1-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| John Geyer | geyer-001joh | 1903 | 5/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Ollie Gfroerer | gfroer001oli | 1903 | 4/25-7/15 | Memphis Egyptians | Southern Association | , | |
| Ollie Gfroerer | gfroer001oli | 1903 | Natchez Indians | Cotton States League | , | ||
| Ollie Gfroerer | gfroer001oli | 1903 | 8/10-9/20 | New Orleans Pelicans | Southern Association | , | |
| Max Gibbs | gibbs-001max | 1903 | 4/25-6/12 | San Antonio Bronchos | South Texas League | , | |
| James Giblin | giblin001jam | 1903 | 5/23-6/1 | Bridgeport Orators | Connecticut League | , | |
| George Gibson | gibson002geo | 1903 | 32 g. | Kingston Colonials | Hudson River League | , | |
| George Gibson | gibson002geo | 1903 | 9/7-9/15 | Buffalo Bisons | Eastern League | , | |
| Norwood Gibson | gibson001nor | 1903 | 4/29- | 25 g. | Boston | American League | Boston, MA |
| Ralph Gibson | gibson001ral | 1903 | 4/22-9/20 | Kansas City Cowboys | American Association | , | |
| Al Gifford | giffor001--- | 1903 | 59 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Billy Gilbert | gilber002wil | 1903 | 128 g. | New York | National League | New York, NY | |
| Gordon Gilbert | gilber001gor | 1903 | preseason | Nashville Volunteers | Southern Association | , | |
| Gordon Gilbert | gilber001gor | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| Gordon Gilbert | gilber001gor | 1903 | +8/15-9/12 | Pulaski | Tennessee-Alabama League | , | |
| Jack Gilbert | gilber005joh | 1903 | 4/25-9/19 | Little Rock Travelers | Southern Association | , | |
| Joseph Gilbert | 1903 | Umpire | Connecticut League | , | |||
| Rufus Gilbert | gilber001ruf | 1903 | Tecumseh Reds | Independent | , | ||
| Denison Giles | giles-001d-- | 1903 | +4/18+ | U. North Carolina | College | , | |
| Denison Giles | giles-001d-- | 1903 | 173 ab | Augusta GA | Independent | , | |
| Bob Gilks | gilks-001rob | 1903 | 5/9-9/20 | Shreveport Giants | Southern Association | , | |
| Roy Gill | gill--002roy | 1903-05 | Washburn College | College | , | ||
| Warren Gill | gill--001war | 1903 | 74 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| John Gilland | gillan000des | 1903 | +4/18+ | U. South Carolina | College | , | |
| Tommy Gilleran | giller001tho | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Thomas Gilligan | gillig001tho | 1903 | 5/1- | Manchester | New England League | , | |
| Thomas Gilligan | gillig001tho | 1903 | Lawrence Colts | New England League | , | ||
| Thomas Gilligan | gillig001tho | 1903 | -7/24 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Thomas Gilligan | 1903 | 7/18-7/27 | Umpire | New England League | , | ||
| George Gillpatrick | gillpa001geo | 1903 | +4/26+ | KS-Athletics | Independent | , | |
| Gilman | 1903 | Dartmouth | College | , | |||
| Gilman | 1903 | Newburyport MA | Independent | , | |||
| C. Gilmore | gilmor001g-- | 1903 | 8/6-9/12 | Haverhill Hustlers | New England League | , | |
| Will Gilreath | gilrea002wil | 1903 | 61 ab | Monroe Hill Citys | Cotton States League | , | |
| Thomas Gilroy | gilroy001tho | 1903 | 5/4- | Lawrence Colts | New England League | , | |
| Thomas Gilroy | gilroy001tho | 1903 | Lowell Tigers | New England League | , | ||
| Thomas Gilroy | gilroy001tho | 1903 | Haverhill Hustlers | New England League | , | ||
| Thomas Gilroy | gilroy001tho | 1903 | -9/11 | Fall River Indians | New England League | , | |
| Frank Gimlin | gimlin001joh | 1903 | -7/5 | Ogden UT | Independent | , | |
| Frank Gimlin | gimlin001joh | 1903 | +7/19+ | Ogden-Eagles | Independent | , | |
| Billy Ging | ging--001bil | 1903 | 5/11-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Patrick Ginley | ginley001pat | 1903 | 5/8-6/6 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Alexander Girard | girard000ale | 1903 | 5/17-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Stephen Girard | girard001ste | 1903 | 5/10 | Olympia Senators | Southwest Washington League | , | |
| Peter Gitzen | 1903 | Millvale PA | Independent | , | |||
| Arthur Glade | glade-000art | 1903 | +5/18+ | Grand Island NE | Independent | , | |
| Arthur Glade | glade-000art | 1903 | +6/24-6/25+ | McCook | Central Nebraska League | , | |
| Fred Glade | glade-001fre | 1903 | 4/28-9/13 | St. Joseph Saints | Western League | , | |
| Phil Glade | glade-001phi | 1903 | 8/8-9/17 | St. Joseph Saints | Western League | , | |
| Wilford Gladfelter | 1903-04 | -6/13 | U. Pennsylvania | College | , | ||
| William Glassburner | glassb001wil | 1903 | Niles OH | Independent | , | ||
| Eddie Glavin | glavin001edw | 1903 | 5/9-9/20 | Binghamton Bingoes | New York State League | , | |
| Herbert Glaze | 1903 | +7/8+ | Orangeburg SC | Independent | , | ||
| Ralph Glaze | glaze-001dan | 1903-05 | Dartmouth College | College | , | ||
| William Glaze | glaze-001w-- | 1903 | +7/8+ | Orangeburg SC | Independent | , | |
| Glazer | glazer000--- | 1903 | +7/14+ | Red Cloud | Central Nebraska League | , | |
| Frank Gleason | gleaso000fra | 1903 | Helena MT | Independent | , | ||
| Harry Gleason | gleaso001har | 1903 | 6 g. | Boston | American League | Boston, MA | |
| Harry Gleason | gleaso001har | 1903 | 5/19-7/7 | Columbus Senators | American Association | , | |
| Harry Gleason | gleaso001har | 1903 | 8/19-9/19 | Columbus Senators | American Association | , | |
| Jimmy Gleason | gleaso000jim | 1903 | 9/6 | Centralia Midgets | Southwest Washington League | , | |
| Kid Gleason | gleaso002wil | 1903 | 106 g. | Philadelphia | National League | Philadelphia, PA | |
| William Gleason | gleaso004wil | 1903 | 38 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Dick Glendon | glendo001ric | 1903 | 6/13-6/21 | Grand Forks Forkers | Northern League | , | |
| Dick Glendon | glendo001ric | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Martin Glendon | glendo001mar | 1903 | 5/2-8/16 | San Francisco Pirates | Pacific National League | , | |
| Martin Glendon | glendo001mar | 1903 | Altoona PA | Independent | , | ||
| Martin Glendon | glendo001mar | 1903 | -9/25 | 3 g. | Cleveland | American League | Cleveland, OH |
| Ed Glenn | glenn-001edw | 1903 | 4/25-8/1 | Memphis Egyptians | Southern Association | , | |
| Ed Glenn | glenn-001edw | 1903 | Natchez Indians | Cotton States League | , | ||
| Glover | glover005--- | 1903 | +7/11+ | Giltner | Central Nebraska League | , | |
| Ed Gnadinger | gnadin001edw | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| John Gochnaur | gochna001joh | 1903 | Cleveland | American League | Cleveland, OH | ||
| John Godwin | godwin001joh | 1903 | 113 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Henry Goff | 1903 | Pacific Coast League | , | ||||
| Ora Goff | 1903 | Elkhart IN | Independent | , | |||
| Ed Gogan | gogan-001ed- | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Eugene Gokey | gokey-001eug | 1903 | 5/1-9/12 | Nashua | New England League | , | |
| John Golden | golden002joh | 1903 | 4/30-6/6 | Toronto Maple Leafs | Eastern League | , | |
| John Golden | golden002joh | 1903 | 6/16-6/18 | Troy Trojans | New York State League | , | |
| John Golden | golden002joh | 1903 | 7/4-9/12 | New Haven Blues | Connecticut League | , | |
| Tom Golden | golden001tho | 1903 | Pottsville PA | Independent | , | ||
| Walt Goldsby | goldsb001wal | 1903 | 5/27-6/14 | Umpire | Southern Association | , | |
| Goldworthy | goldwo000--- | 1903 | 5/21-8/16+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Goldworthy | goldwo000--- | 1903 | postseason | Sioux Falls SD | Independent | , | |
| Johnny Gonding | gondin001joh | 1903 | 4/30-9/17 | Omaha Indians | Western League | , | |
| Valentin Gonzalez | 1903 | Habana | Cuban Winter League | , | |||
| Abraham Goodman | goodma000abe | 1903 | +8/10+ | Helena-Juniors | Independent | , | |
| Frank Goodman | 1903 | Columbia Univ. | College | , | |||
| Goodwin | goodwi013--- | 1903 | 5/21-6/29,7/21 | Norwich Reds | Connecticut League | , | |
| Art Goodwin | goodwi001art | 1903 | 5/9-7/6 | Albany Senators | New York State League | , | |
| Art Goodwin | goodwi001art | 1903 | 7/18-9/15 | Schenectady Frog Alleys | New York State League | , | |
| Clyde Goodwin | goodwi001cly | 1903 | 7/22-9/13 | Evansville River Rats | Central League | , | |
| Gordon | gordon025--- | 1903 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | ||
| D. S. Gordon | gordon000ds- | 1903 | 5/21-6/6 | Superior Longshoremen | Northern League | , | |
| Eddie Gordon | gordon002a-- | 1903 | 5/3-5/31 | Denver Grizzlies | Western League | , | |
| Eddie Gordon | gordon002a-- | 1903 | 6/19 | Fargo | Northern League | , | |
| Eddie Gordon | gordon002a-- | 1903 | Portage la Pairie | Manitoba | , | ||
| Grant Gorman | 1903 | 5/21-9/16 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Gormully | gormul001--- | 1903 | 9/8-9/15 | Marion Oilworkers | Central League | , | |
| Ly Gorton | gorton001lym | 1903 | 168 g. | Oakland Oaks | Pacific Coast League | , | |
| Roger Gorton | gorton001rog | 1903 | +5/12-8/16+ | Holland MI | Independent | , | |
| Claude Gouzzie | gouzzi001cla | 1903 | +6/20+ | Niles OH | Independent | , | |
| Claude Gouzzie | gouzzi001cla | 1903 | 7/22 | St. Louis | American League | St. Louis, MO | |
| Mike Grady | grady-002mic | 1903 | 4/22-9/21 | Kansas City Cowboys | American Association | , | |
| William Graffius | graffi001wil | 1903 | 4/25-9/20 | Shreveport Giants | Southern Association | , | |
| Vincent Gragion | gragio000vin | 1903 | +6/30+ | St. Mary’s | Rochester Catholic | , | |
| Charlie Graham | graham002cha | 1903 | Santa Clara Univ. | College | , | ||
| Charlie Graham | graham002cha | 1903 | 178 g. | Sacramento Senators | Pacific Coast League | , | |
| Earl Graham | graham001ear | 1903 | 62 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Harry Graham | graham002har | 1903 | 6/7-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Moonlight Graham | graham001arc | 1903 | U. of Maryland | College | , | ||
| Moonlight Graham | graham001arc | 1903 | 5/1- | Nashua | New England League | , | |
| Moonlight Graham | graham001arc | 1903 | -9/12 | Manchester | New England League | , | |
| Oscar Graham | graham001osc | 1903 | 86 g. | Oakland Oaks | Pacific Coast League | , | |
| Peaches Graham | graham002geo | 1903 | 117 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Peaches Graham | graham002geo | 1903 | 1 g. | Chicago | National League | Chicago, IL | |
| Grant | 1903 | 6/1-8/17 | Umpire | Northern League | , | ||
| Angus Grant | grant-001ang | 1903 | 4/30-9/16 | South Bend Greens | Central League | , | |
| Benjamin Grant | grant-001ben | 1903 | no g. | Sedalia Goldbugs | Missouri Valley League | , | |
| C. W. Grant | grant-000cw- | 1903 | 8/30-9/6 | Olympia Senators | Southwest Washington League | , | |
| Eddie Grant | grant-001edw | 1903-05 | Harvard Univ | College | , | ||
| Eddie Grant | grant-001edw | 1903 | Independent | , | |||
| George Grant | grant-003geo | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| George Grant | grant-003geo | 1903 | -9/12 | Lowell Tigers | New England League | , | |
| Arthur Granville | granvi001art | 1903 | 4/28-9/6 | Colorado Springs Millionaires | Western League | , | |
| Frank Graves | graves002fra | 1903 | 5/21-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Frank Graves | graves002fra | 1903 | +8/1-8/9+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Gray | 1903 | 5/11-9/8 | Umpire | Connecticut League | , | ||
| Billy Gray | gray--003bil | 1903 | Camden NJ | Independent | , | ||
| Chummy Gray | gray--001chu | 1903 | 5/1-6/10 | Providence Grays | Eastern League | , | |
| Chummy Gray | gray--001chu | 1903 | 7/16-9/19 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Clarence Gray | gray--001cla | 1903 | 7/30-8/25 | Corsicana Oil Citys | Texas League | , | |
| Dolly Gray | gray--003wil | 1903 | 51 g. | Los Angeles Angels | Pacific Coast League | , | |
| Leonard Gray | gray--001leo | 1903 | 6/8-7/24 | Holdredge | Central Nebraska League | , | |
| Will Gray | gray--002wil | 1903 | 17 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| William Gray | gray--001w-- | 1903 | +6/9-9/4+ | Sedalia Goldbugs | Missouri Valley League | , | |
| Green | green-079--- | 1903 | 8/19-9/12 | Nashua | New England League | , | |
| Green | green-081--- | 1903 | 8 g. | Montgomery Black Sox | Interstate League | , | |
| Charles Green | green-015--- | 1903 | 5/10-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Danny Green | green-001edw | 1903 | 135 g. | Chicago | American League | Chicago, IL | |
| E. E. Green | green-002e-- | 1903 | 5/10-7/12 | Aberdeen Pippins | Southwest Washington League | , | |
| Earl Green | green-001ear | 1903 | 5/2-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Johnny Green | green-001joh | 1903 | 48 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| A.V. Greene | greene001a-- | 1903 | +7/20+ | Rock Rapids | Independent | , | |
| Ernest Greene | greene001ern | 1903 | 6/16-9/11 | Concord Marines | New England League | , | |
| Paddy Greene | greene001pat | 1903 | 4/30-6/22 | Baltimore Orioles | Eastern League | , | |
| Paddy Greene | greene001pat | 1903 | 7/11 - | 4 g. | New York | American League | New York, NY |
| Paddy Greene | greene001pat | 1903 | 7/17 | Detroit | American League | Detroit, MI | |
| Paddy Greene | greene001pat | 1903 | 8/3-8/11 | Toronto Maple Leafs | Eastern League | , | |
| Teddy Greene | greene001ted | 1903 | Webster City IA | Independent | , | ||
| Jack Greenwell | greenw003joh | 1903 | Ogden-Wesslers | Independent | , | ||
| Greer | greer-001--- | 1903 | +8/16+ | Pulaski | Tennessee-Alabama League | , | |
| Hunter Gregg | gregg-001hun | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| James? Gregory | gregor024--- | 1903 | Sioux City Soos | Iowa-South Dakota League | , | ||
| James? Gregory | gregor024--- | 1903 | Marshalltown IA | Independent | , | ||
| Ed Gremminger | gremmi001lor | 1903 | 140 g. | Boston | National League | Boston, MA | |
| Reddy Grey | grey--001rom | 1903 | 5/28 | Pittsburgh | National League | Pittsburgh, PA | |
| Reddy Grey | grey--001rom | 1903 | 5/29-6/13 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Reddy Grey | grey--001rom | 1903 | 8/7-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Charles Grieshaber | griesh000cha | 1903 | Hudson Marines | Hudson River League | , | ||
| Griffin | griffi077--- | 1903 | 7/19 | Schenectady Frog Alleys | New York State League | , | |
| Griffin | griffi075--- | 1903 | 9/23-9/25 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| C. C. Griffin | 1903 | 6/- | Colfax | Inland Empire League | , | ||
| J. G. Griffin | griffi002j-- | 1903 | Niagara Univ | College | , | ||
| J. G. Griffin | griffi002j-- | 1903 | 7/2-9/18 | Albany Senators | New York State League | , | |
| Sandy Griffin | griffi001san | 1903 | 5/8-9/20 | Syracuse Stars | New York State League | , | |
| Steve Griffin | griffi001ste | 1903 | 4/30-5/8 | Jersey City Skeeters | Eastern League | , | |
| Steve Griffin | griffi001ste | 1903 | 6/9-9/26 | Baltimore Orioles | Eastern League | , | |
| T. Griffin | griffi002j-- | 1903 | 6/7-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Jack Grim | grim--001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | ||
| Jack Grim | grim--001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| John Grim | grim--002joh | 1903 | 4/30-09/11 | Marion Oilworkers | Central League | , | |
| James Grimes | grimes003jam | 1903 | Bozeman MT | Independent | , | ||
| Huber Grimm | grimm-000hub | 1903 | Olym.-Clerks | Independent | , | ||
| Huber Grimm | grimm-000hub | 1903 | 9/6 | Olympia Senators | Southwest Washington League | , | |
| Myron Grimshaw | grimsh001myr | 1903 | 4/30-8/29 | Buffalo Bisons | Eastern League | , | |
| William Groeschow | groesc001wil | 1903 | 5/1-5/27 | Dayton Veterans | Central League | , | |
| William Groeschow | groesc001wil | 1903 | 5/28-9/16 | South Bend Greens | Central League | , | |
| Grogan | 1903 | Knox College | College | , | |||
| John Grogan | grogan004joh | 1903 | 36 g. | Sioux City Soos | Iowa-South Dakota League | , | |
| James Gronninger | gronin001jam | 1903-06 | U. West Virginia | College | , | ||
| James Gronninger | gronin001jam | 1903 | +6/14-8/16+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Harry Gross | gross-002har | 1903 | no g. | Sedalia Goldbugs | Missouri Valley League | , | |
| Harry Gross | gross-002har | 1903 | 6/9,8/10,8/20 | Springfield Midgets | Missouri Valley League | , | |
| Harry Gross | gross-002har | 1903 | 6/12 | Iola Gaslighters | Missouri Valley League | , | |
| Harry Gross | gross-002har | 1903 | +9/1+ | Spri.-Garnett | Independent | , | |
| Grover | grover012--- | 1903 | 7/2-7/4 | Troy Trojans | New York State League | , | |
| George Groves | groves001geo | 1903 | Jacksonville FL | Independent | , | ||
| Frank Grubbs | grubbs002fra | 1903 | 7/2-9/13 | Terre Haute Hottentots | Central League | , | |
| Louis Gruebner | gruebn001lou | 1903 | 4/27-6/23 | Atlanta Crackers | Southern Association | , | |
| Louis Gruebner | gruebn001lou | 1903 | 70 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Louis Guernsey | guerns001lou | 1903 | 5/12-6/22 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Whitey Guese | guese-001the | 1903 | 4/26-9/17 | Little Rock Travelers | Southern Association | , | |
| Frank Guest | guest-001fra | 1903 | 5/2- | Haverhill Hustlers | New England League | , | |
| Frank Guest | guest-001fra | 1903 | -5/19 | Nashua | New England League | , | |
| Frank Guest | guest-001fra | 1903 | Chester PA | Independent | , | ||
| Thomas Guiheen | guihee001tho | 1903 | 5/1-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Thomas Guiheen | guihee001tho | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Gunion | gunion000--- | 1903 | 8/26-8/29 | Marion Oilworkers | Central League | , | |
| Frank Gunther | gunthe001fra | 1903 | Hornellsville NY | Independent | , | ||
| J. Gustropski/Go | 1903 | 7/27-9/12 | Bridgeport Orators | Connecticut League | , | ||
| Guyn | 1903 | 7/4-7/27+ | Jacksonville FL | Independent | , | ||
| Isaac Guyn | guyn--001how | 1903 | 4/4- | U. Kentucky | College | , | |
| Isaac Guyn | guyn--001how | 1903 | 6/15- | Rome Romans | Alabama-Georgia League | , | |
| Frank Gygli | gygli-001fra | 1903 | -10/18 | Clev.-East Ends | Independent | , | |
| A. Haas | 1903 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |||
| Bert Haas | haas--001ber | 1903 | Sidney OH | Independent | , | ||
| Clarence Haas | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Jim Hackett | hacket001jam | 1903 | 99 g. | St. Louis | National League | St. Louis, MO | |
| Tom Hackett | hacket001tho | 1903 | -6/2 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Tom Hackett | hacket001tho | 1903 | Oakland Heeseman | California State League | , | ||
| Hardy Hadden | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | |||
| Louis Hading | hading001lou | 1903 | 8/31-9/20 | Toledo Mud Hens | American Association | , | |
| Hubert Hadley | hadley001hub | 1903 | Terre Haute Hottentots | Central League | , | ||
| Hubert Hadley | hadley001hub | 1903 | Fargo | Northern League | , | ||
| Hubert Hadley | hadley001hub | 1903 | Flint | Southern Michigan | , | ||
| Frank Hafford | haffor001fra | 1903 | 5/1-9/12 | Lowell Tigers | New England League | , | |
| Raymond Hagan | hagan-001ray | 1903 | Atlantic City | Independent | , | ||
| Alf Hagerman | hagerm001alf | 1903 | 57 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Alf Hagerman | hagerm001alf | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| Peter Hagerty | hagert001pet | 1903 | , | ||||
| Ed Hahn | hahn--003wil | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Frank Hahn | hahn--017--- | 1903 | Wellsville NY | Independent | , | ||
| Noodles Hahn | hahn--001fra | 1903 | Cincinnati | National League | Cincinnati, OH | ||
| Louis Haidt | haidt-001lou | 1903 | 12 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | |
| Louis Haidt | haidt-001lou | 1903 | 6/1-6/3 | Fort Wayne Railroaders | Central League | , | |
| Benjamin Halbert | halber001f-- | 1903 | 5/24-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Louis Halbritter | halbri001lou | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Ed Hale | hale--001ed- | 1903 | no g. | San Antonio Bronchos | South Texas League | , | |
| Harry Hale | hale--000har | 1903 | 4/28 | Atlanta Crackers | Southern Association | , | |
| Jess Hale | hale--001jes | 1903 | 5/8-7/16 | Schenectady Frog Alleys | New York State League | , | |
| Ray Hale | hale--001ray | 1903 | 4/25-7/2 | Milwaukee Brewers | American Association | , | |
| Ray Hale | hale--001ray | 1903 | 7/19-9/15 | Memphis Egyptians | Southern Association | , | |
| Hall | hall--080--- | 1903 | 8/23-8/24 | Iola Gaslighters | Missouri Valley League | , | |
| Hall | hall--081--- | 1903 | +6/13+ | Holdredge | Central Nebraska League | , | |
| Bob Hall | hall--004rob | 1903 | 5/7-8/27 | New Haven Blues | Connecticut League | , | |
| Bob Hall | hall--004rob | 1903 | 8/31-9/17 | Milwaukee Creams | Western League | , | |
| Louis Hall | hall--001lou | 1903 | 5/20-6/28 | Superior Longshoremen | Northern League | , | |
| Russ Hall | hall--011rob | 1903 | 4/14-8/16 | Los Angeles | Pacific National League | , | |
| Russ Hall | hall--011rob | 1903 | 9/10-9/21 | Kansas City Cowboys | American Association | , | |
| Rusty Hall | hall--001war | 1903 | 53 g. | Los Angeles Angels | Pacific Coast League | , | |
| John Halla | halla-001joh | 1903 | 5/1-8/6 | Kansas City Blue Stockings | Western League | , | |
| John Halla | halla-001joh | 1903 | 8/12-9/7 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Jocko Halligan | hallig001joc | 1903 | 4/30-9/26 | Jersey City Skeeters | Eastern League | , | |
| Bill Hallman | hallma002wil | 1903 | - 9/27 | 63 g. | Philadelphia | National League | Philadelphia, PA |
| Bill Hallman | hallma001wil | 1903 | 63 g. | Chicago | American League | Chicago, IL | |
| William Hamacher | hamach000wil | 1903 | 5/15-5/22 | Utica Pent-Ups | New York State League | , | |
| Charlie Hamburg | hambur003cha | 1903 | Greenville Grays | Cotton States League | , | ||
| Francis Hamer | hamer-000fra | 1903 | 5/2-5/27 | Fort Scott Giants | Missouri Valley League | , | |
| Argus Hamilton | hamilt001arg | 1903 | no g. | Indianapolis Indians | American Association | , | |
| Argus Hamilton | hamilt001arg | 1903 | 5/8-8/3 | Marion Oilworkers | Central League | , | |
| Billy Hamilton | hamilt006wil | 1903 | 5/1-6/18 | Haverhill Hustlers | New England League | , | |
| John Hamilton | 1903 | 5/6-7/1 | Umpire | Missouri Valley League | , | ||
| Sandy Hamilton | hamilt001ale | 1903 | 5/2-5/19 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Sandy Hamilton | hamilt001ale | 1903 | +5/24-7/29+ | Weir City KS | Independent | , | |
| Hamm | 1903 | 5/28-6/3 | Umpire | Central League | , | ||
| John Hammond | hammon001joh | 1903 | 1 g. | Oakland Oaks | Pacific Coast League | , | |
| Hand | hand--006--- | 1903 | 9/19 | Baltimore Orioles | Eastern League | , | |
| William Handiboe | handib002wil | 1903 | 27 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Jim Haney | haney-003jam | 1903 | 5/23-8/6 | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Charles Hanford | 1903 | +8/22+ | Tren.-YMCA | Independent | , | ||
| Chip Hanford | hanfor002cha | 1903 | 5/1-5/12 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Chip Hanford | hanfor002cha | 1903 | 5/25-5/29 | Terre Haute Hottentots | Central League | , | |
| Chip Hanford | hanfor002cha | 1903 | 6/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Chip Hanford | hanfor002cha | 1903 | Youngstown OH | Independent | , | ||
| Haniford | hanifo000--- | 1903 | 5/31-6/22 | Albany Senators | New York State League | , | |
| Jack Hankey | hankey001joh | 1903 | 98 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Arthur Hanks | hanks-001art | 1903 | +4/29-7/25+ | York-Penn’sPark | Independent | , | |
| Arthur Hanks | hanks-001art | 1903 | +9/5+ | Linder PA | Independent | , | |
| George Hanley | hanley002geo | 1903 | 4/14-10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland/SLC, | |
| Joseph Hanley | hanley000jos | 1903 | +5/26+ | 2 g. | Duluth Cardinals | Northern League | , |
| Joseph Hanley | hanley000jos | 1903 | Cando ND | Independent | , | ||
| Bill Hanlon | hanlon001wil | 1903 | 4/16-4/26 | Chicago | National League | Chicago, IL | |
| Bill Hanlon | hanlon001wil | 1903 | 19 g. | Seattle Siwashes | Pacific Coast League | , | |
| Bill Hanlon | hanlon001wil | 1903 | 7/23- | 21 g. | Tacoma Tigers | Pacific National League | , |
| William Hanna | hanna-003wil | 1903 | Saugerties | Hudson River League | , | ||
| John Hannafin | 1903 | 6/6-9/12 | Norwich Reds | Connecticut League | , | ||
| Larry Hannafin | hannaf001law | 1903 | 5/9-9/12 | New Haven Blues | Connecticut League | , | |
| Jack Hannifin | hannif002joh | 1903 | 63 g. | Norwich Reds | Connecticut League | , | |
| Pat Hannivan | hanniv001pat | 1903 | 76 g. | Seattle Siwashes | Pacific Coast League | , | |
| Pat Hannivan | hanniv001pat | 1903 | 39 g. | Seattle Chinooks | Pacific National League | , | |
| Pat Hannivan | hanniv001pat | 1903 | +8/2-8/16 | Tacoma Tigers | Pacific National League | , | |
| Hanover | hanove000--- | 1903 | 7/30 | Haverhill Hustlers | New England League | , | |
| Billy Hanrahan | hanrah001wil | 1903 | 90 g. | Grand Forks Forkers | Northern League | , | |
| Jack Hanrahan | hanrah001joh | 1903 | 1 g. | Oakland Oaks | Pacific Coast League | , | |
| Eddie Hanscomb | hansco001edm | 1903 | 5/9-5/12 | Nashua | New England League | , | |
| Eddie Hanscomb | hansco001edm | 1903 | Newport NH | Independent | , | ||
| George Hanson | hanson001geo | 1903 | 4/14-5/31+ | Los Angeles | Pacific National League | , | |
| George Hanson | hanson001geo | 1903 | +7/26-10/3 | Spokane Indians | Pacific National League | , | |
| Scott Hardesty | hardes002sco | 1903 | 5/9-6/16 | New London Whalers | Connecticut League | , | |
| Scott Hardesty | hardes002sco | 1903 | 6/18-7/11 | Springfield Ponies | Connecticut League | , | |
| Scott Hardesty | hardes002sco | 1903 | 7/23-7/28 | Nashua | New England League | , | |
| Scott Hardesty | hardes002sco | 1903 | 8/15 | Hartford Senators | Connecticut League | , | |
| Hardt | hardt-001--- | 1903 | 8/5-9/21 | Rochester Bronchos | Eastern League | , | |
| Alex Hardy | hardy-001dav | 1903 | -5/9 | 3 g. | Chicago | National League | Chicago, IL |
| Alex Hardy | hardy-001dav | 1903 | 5/16-7/19 | Toronto Maple Leafs | Eastern League | , | |
| Alex Hardy | hardy-001dav | 1903 | 9/7-9/24 | Buffalo Bisons | Eastern League | , | |
| Ellis Hardy | hardy-001ell | 1903 | 4/25-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Harry Hardy | hardy-001har | 1903 | Dubois PA | Independent | , | ||
| Harry Hardy | hardy-001har | 1903 | 9/17 | Columbus Senators | American Association | , | |
| Jack Hardy | hardy-001joh | 1903 | 4/19- | 74 g. | Los Angeles | Pacific National League | , |
| Jack Hardy | hardy-001joh | 1903 | 7/23-8/3 | Fort Wayne Railroaders | Central League | , | |
| Jack Hardy | hardy-001joh | 1903 | 8/29- | 5 g. | Cleveland | American League | Cleveland, OH |
| Jack Hardy | hardy-001joh | 1903 | 9/6-9/15 | Fort Wayne Railroaders | Central League | , | |
| Harkness | harkne003--- | 1903 | 1 g. | Winnipeg Maroons | Northern League | , | |
| Dick Harley | harley001ric | 1903 | - 9/21 | 104 g. | Chicago | National League | Chicago, IL |
| Dick Harley | harley001hen | 1903 | 4/27 | Memphis Egyptians | Southern Association | , | |
| Dick Harley | harley001hen | 1903 | 16-12 | Baton Rouge Red Sticks | Cotton States League | , | |
| William Harley | harley001wil | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Con Harlow | harlow001con | 1903 | 22 g. | Portland Browns | Pacific Coast League | , | |
| Con Harlow | harlow001con | 1903 | 5/17-7/5 | Aberdeen Pippins | Southwest Washington League | , | |
| Con Harlow | harlow001con | 1903 | 213 ab | Natchez Indians | Cotton States League | , | |
| Ira Harmon | harmon001ira | 1903 | 4/15-5/21+ | Tacoma Tigers | Pacific National League | , | |
| Ira Harmon | harmon001ira | 1903 | 6/6-6/12+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Ira Harmon | harmon001ira | 1903 | 7/12-9/6 | Centralia Midgets | Southwest Washington League | , | |
| Ira Harmon | harmon001ira | 1903 | -10/3 | Seattle Chinooks | Pacific National League | , | |
| Walter Harmon | harmon001wal | 1903 | 5/11-5/14 | Bridgeport Orators | Connecticut League | , | |
| Walter Harmon | harmon001wal | 1903 | Ossining/Catskill | Hudson River League | Catskill, | ||
| Nick Harnish | harnis001nic | 1903 | 8/1-8/2 | Dayton Veterans | Central League | , | |
| L. J. Harnson | harnso000lj- | 1903 | Saugerties | Hudson River League | , | ||
| Jack Harper | harper003cha | 1903 | 19 g. | Cincinnati | National League | Cincinnati, OH | |
| Guy Harrington | harrin001guy | 1903 | 5/2-6/15 | Joplin Miners | Missouri Valley League | , | |
| Guy Harrington | harrin001guy | 1903 | 6/30 | Springfield Midgets | Missouri Valley League | , | |
| Guy Harrington | harrin001guy | 1903 | 7/8-9/27 | Joplin Miners | Missouri Valley League | , | |
| Joe Harrington | harrin001joe | 1903 | 5/7-9/12 | Norwich Reds | Connecticut League | , | |
| Harris | harris114--- | 1903 | 7/24 | San Antonio Bronchos | South Texas League | , | |
| Charles Harris | harris002c-- | 1903 | 5/22-7/25+ | Grand Forks Forkers | Northern League | , | |
| Charles Harris | harris002c-- | 1903 | 8/17-9/8 | Umpire | Northern League | , | |
| Ewing Harris | harris001ewi | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| F. G. Harris | harris000fg- | 1903 | 8/8-9/20 | Binghamton Bingoes | New York State League | , | |
| Joe Harris | harris007jos | 1903 | 6/8- | Concord Marines | New England League | , | |
| Joe Harris | harris007jos | 1903 | Lawrence Colts | New England League | , | ||
| Joe Harris | harris007jos | 1903 | -9/9 | Fall River Indians | New England League | , | |
| John Harris | harris001joh | 1903 | Baylor Univ. | College | , | ||
| Joseph Harris | harris002jos | 1903 | Ionia MI | Independent | , | ||
| Eldred Harrison | harris000eld | 1903 | 5/16-5/26 | Sedalia Goldbugs | Missouri Valley League | , | |
| John Harrison | harris012joh | 1903 | 8/19-9/12 | Lawrence Colts | New England League | , | |
| Bill Hart | hart--004wil | 1903 | 4/30-9/13 | Peoria Distillers | Western League | , | |
| Eugene Hart | hart--001eug | 1903 | 5/19-9/12 | Lawrence Colts | New England League | , | |
| Jimmy Hart | hart--003jam | 1903 | 4/22-5/17 | Columbus Senators | American Association | , | |
| Jimmy Hart | hart--003jam | 1903 | 5/23-5/30 | Minneapolis Millers | American Association | , | |
| Jimmy Hart | hart--003jam | 1903 | 6/3-9/20 | Louisville Colonels | American Association | , | |
| Thomas Hart | hart--002tho | 1903 | 5/1-9/14 | Dayton Veterans | Central League | , | |
| Chick Hartley | hartle001wal | 1903 | +8/18-10/12 | Harrisburg PA | Independent | , | |
| James Hartley | hartle001jam | 1903 | 7/29-9/8 | Grand Forks Forkers | Northern League | , | |
| Fred Hartman | hartma003fre | 1903 | 4/30-9/26 | Buffalo Bisons | Eastern League | , | |
| William Hartman | hartma001wil | 1903 | 4/28-9/17 | St. Joseph Saints | Western League | , | |
| Roy Hartzell | hartze001roy | 1903 | 4/30-6/7 | Denver Grizzlies | Western League | , | |
| Roy Hartzell | hartze001roy | 1903 | 6/22-9/17 | Peoria Distillers | Western League | , | |
| Harvey | harvey011--- | 1903 | 8/24-9/17 | Des Moines Undertakers | Western League | , | |
| James Harvey | harvey001jam | 1903 | Dayton Veterans | Central League | , | ||
| Leon Harvey | harvey000leo | 1903 | no g. | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Jack Haskell | haskel001jac | 1903 | 4/22-7/15 | Umpire | American Association | , | |
| Jack Haskell | haskel001jac | 1903 | 8/4-9/20 | Umpire | American Association | , | |
| William Haslem | haslem001wil | 1903 | no g. | New Orleans Pelicans | Southern Association | , | |
| William Haslem | haslem001wil | 1903 | Warren OH | , | |||
| William Haslem | haslem001wil | 1903 | 6/16-9/20 | Syracuse Stars | New York State League | , | |
| Christy Hassett | hasset001chr | 1903 | 6/21-9/20 | Umpire | New York State League | , | |
| James Hassett | 1903 | 93 g. | MLB Umpire | American League | , | ||
| Charlie Hastings | hastin002cha | 1903 | 5/11-7/27 | Albany Senators | New York State League | , | |
| Charlie Hastings | hastin002cha | 1903 | 8/14-9/20 | New Orleans Pelicans | Southern Association | , | |
| Bill Hausen | hausen001hom | 1903 | +5/10-6/29+ | Ogden UT | Independent | , | |
| Bill Hausen | hausen001hom | 1903 | 61 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Bill Hausen | hausen001hom | 1903 | 9/24-10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Sam Havel | havel-001edw | 1903 | 5/1-9/16 | Dayton Veterans | Central League | , | |
| John Haviland | havila001joh | 1903 | +7/11-7/26+ | Creston Cyclones | Southwest Iowa League | , | |
| Buck Hawkins | hawkin001tho | 1903 | Muncie IN | Independent | , | ||
| Buck Hawkins | hawkin001tho | 1903 | Dayton Veterans | Central League | , | ||
| Omar Hawkins | 1903 | Fort Worth Panthers | Texas League | , | |||
| R.L. Hawkins | hawkin000rl- | 1903 | Harvard Univ. | College | , | ||
| Thomas Hawkins | hawkin001tho | 1903 | Muncie IN | Independent | , | ||
| Thomas Hawkins | hawkin001tho | 1903 | 7/11-7/16 | Dayton Veterans | Central League | , | |
| Thomas Hawkins | hawkin001tho | 1903 | Muncie IN | Independent | , | ||
| Hawley | hawley007--- | 1903 | 8/24 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Pink Hawley | hawley001eme | 1903 | , | ||||
| Jack Hayden | hayden001joh | 1903 | 4/30-6/6 | Rochester Bronchos | Eastern League | , | |
| Jack Hayden | hayden001joh | 1903 | 6/9-9/26 | Baltimore Orioles | Eastern League | , | |
| Gerald Hayes | hayes-001ger | 1903 | 4/25-7/30 | Houston Buffaloes | South Texas League | , | |
| Gerald Hayes | hayes-001ger | 1903 | 8/2-8/30 | San Antonio Bronchos | South Texas League | , | |
| Jack Hayes | 1903 | 4/25-5/20,7/7 | Umpire | South Texas League | , | ||
| James Hayes | hayes-005jam | 1903 | 5/1-9/13 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Thomas Hayes | hayes-002tom | 1903 | 5/1-9/12 | Concord Marines | New England League | , | |
| William Hayes | 1903-05 | Denver | Western League | , | |||
| Hays/Hayes | 1903 | 6/10-6/12+ | Fort Scott Giants | Missouri Valley League | , | ||
| Clarence Haythorn | haytho001cla | 1903 | 4/25-5/13 | Houston Buffaloes | South Texas League | , | |
| Clarence Haythorn | haytho001cla | 1903 | 7/11-7/28 | Houston Buffaloes | South Texas League | , | |
| William Hayward | haywar001wil | 1903 | 5/7-9/12 | New Haven Blues | Connecticut League | , | |
| Ben Hayworth | haywor001ben | 1903 | Matthews IN | Independent | , | ||
| Ben Hayworth | haywor001ben | 1903 | 6/23-6/25 | Marion Oilworkers | Central League | , | |
| Doc Hazelton | hazlet001wil | 1903 | 5/8-7/8 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Doc Hazelton | hazlet001wil | 1903 | Burlington | Northern New York League | , | ||
| Head | 1903-04 | Cumberland Col | College | , | |||
| Claire Head | head--002cla | 1903 | 1 g. | Los Angeles Angels | Pacific Coast League | , | |
| Walter Headon | headon000wal | 1903 | 4/25-6/4 | Galveston Sand Crabs | South Texas League | , | |
| Walter Headon | headon000wal | 1903 | 8/17-8/26 | Houston Buffaloes | South Texas League | , | |
| James Heaney | heaney000jam | 1903 | Hudson Marines | Hudson River League | , | ||
| Hughie Hearne | hearne001hug | 1903 | - 7/2 | 26 g. | Brooklyn | National League | Brooklyn, NY |
| Hughie Hearne | hearne001hug | 1903 | 7/4-9/26 | Baltimore Orioles | Eastern League | , | |
| Al Hecht | hecht-001al- | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| George Heckert | hecker001geo | 1903 | York-Penn's’ Park | Independent | , | ||
| Heder | 1903 | +5/28-6/14 | Walla Walla | Inland Empire League | , | ||
| Heder | 1903 | Chemera OR | Independent | , | |||
| Alonzo Hedges | hedges001alo | 1903 | 7/15-9/10 | Milwaukee Brewers | American Association | , | |
| John Heehan | 1903 | 5/26-6/3 | Terre Haute Hottentots | Central League | , | ||
| Jimmie Heffernan | heffer001jam | 1903 | Syracuse Univ. | College | , | ||
| Jimmie Heffernan | heffer001jam | 1903 | Greenfield MA | Independent | , | ||
| Heflin | 1903 | 8/1 | Anniston Invincibles | Alabama-Georgia League | , | ||
| Emmet Heidrick | heidri001joh | 1903 | 120 g. | St. Louis | American League | St. Louis, MO | |
| John Heileman | heilem001joh | 1903 | 4/25-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Jacob Heir | heir--000jak | 1903 | 5/8-6/14 | Springfield Midgets | Missouri Valley League | , | |
| John Heisman | 1903 | Clemson Univ. | College | , | |||
| Crese Heismann | heisma001chr | 1903 | 5/8-6/14 | Helena Senators | Pacific National League | , | |
| Crese Heismann | heisma001chr | 1903 | -7/19 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| James Helms | helm--001jam | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Frederick Helmsdorfer | helmsd001fre | 1903 | 5/21-8/16+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| George Hemming | hemmin002geo | 1903 | 5/2-6/9 | Toronto Maple Leafs | Eastern League | , | |
| George Hemming | hemmin002geo | 1903 | 6/26-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| George Hemming | hemmin002geo | 1903 | 7/20-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Charlie Hemphill | hemphi001cha | 1903 | 105 g. | St. Louis | American League | St. Louis, MO | |
| Frank Hemphill | hemphi001fra | 1903 | 35 g. | Seattle Siwashes | Pacific Coast League | , | |
| Frank Hemphill | hemphi001fra | 1903 | 5/19-9/21 | Milwaukee Brewers | American Association | , | |
| Ben Henderson | hender003jam | 1903 | 5/1-8/24 | Omaha Indians | Western League | , | |
| Harvey Henderson | hender005har | 1903 | Syracuse Univ | College | , | ||
| Harvey Henderson | hender005har | 1903 | 6/18-7/28 | Ilion Typewriters | New York State League | , | |
| Johnny Hendley | hendle001joh | 1903 | 86 g. | Iola Gaslighters | Missouri Valley League | , | |
| Jack Hendricks | hendri002joh | 1903 | 4/14-8/ | Spokane Indians | Pacific National League | , | |
| Jack Hendricks | hendri002joh | 1903 | -9/28 | 32 g. | Washington | American League | Washington, DC |
| Newt Hendrix | hendri001new | 1903 | 5/14- | Decatur AL | Independent | , | |
| Newt Hendrix | hendri001new | 1903 | +8/15+ | 3 g. | Decatur | Tennessee-Alabama League | , |
| Henebey/Heneby | 1903 | 5/8-5/14 | Springfield Ponies | Connecticut League | , | ||
| Henley | henley005--- | 1903 | 5/2-9/26 | Iola Gaslighters | Missouri Valley League | , | |
| Weldon Henley | henley001wel | 1903 | 4/23- | 30 g. | Philadelphia | American League | Philadelphia, PA |
| Joe Hennegar | henneg001jos | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Joe Hennegar | henneg001jos | 1903 | 7/20-9/19 | Little Rock Travelers | Southern Association | , | |
| Joe Hennessey | hennes001jos | 1903 | 4/25-9/20 | Shreveport Giants | Southern Association | , | |
| Lawrence Henretty | henret000lar | 1903 | Georgetown Univ | College | , | ||
| Lawrence Henretty | henret000lar | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Henry | 1903 | Camden NJ | Independent | , | |||
| George Henry | henry-002geo | 1903 | 5/9-9/12 | Springfield Ponies | Connecticut League | , | |
| Jack Henry | henry-001joh | 1903 | 5/2-6/15 | Leavenworth White Sox | Missouri Valley League | , | |
| Jack Henry | henry-001joh | 1903 | +8/29+ | 35 g. | Butte Miners | Pacific National League | , |
| Frank Herbert | herber001fra | 1903 | 4/30-9/16 | Marion Oilworkers | Central League | , | |
| Jack Herbert | herber003joh | 1903 | 110 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Art Herman | herman001art | 1903 | 4/27-9/17 | Nashville Volunteers | Southern Association | , | |
| C. V. Herr | herr--000dut | 1903 | 5/2-5/19 | Leavenworth White Sox | Missouri Valley League | , | |
| Eddie Herr | herr--002edw | 1903 | 22 g. | Oakland Oaks | Pacific Coast League | , | |
| Eddie Herr | herr--002edw | 1903 | 23 g. | San Francisco Seals | Pacific Coast League | , | |
| Frank Hershey | hershe001fra | 1903 | 9/5-9/19 | Ilion Typewriters | New York State League | , | |
| John Herwig | herwig001joh | 1903 | +5/12+ | Reading PA | Independent | , | |
| Fred Herzog | herzog001fre | 1903 | 5/1-5/21 | Fall River Indians | New England League | , | |
| Hess | hess--001art | 1903 | 100 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Hess | hess--001art | 1903 | 9/16-9/20 | Indianapolis Indians | American Association | , | |
| Hess | hess--009--- | 1903 | 7/10-7/25 | Binghamton Bingoes | New York State League | , | |
| Harry Hess | hess--001har | 1903 | 5/11-7/5 | Ilion Typewriters | New York State League | , | |
| Otto Hess | hess--001ott | 1903 | 4/30-9/12 | Kansas City Blue Stockings | Western League | , | |
| Tom Hess | hess--001tho | 1903 | 5/8-5/13 | Albany Senators | New York State League | , | |
| Tom Hess | hess--001tho | 1903 | 56 g. | Portland Browns | Pacific Coast League | , | |
| George Hessler | hessle001geo | 1903 | 5/8-9/17 | Peoria Distillers | Western League | , | |
| Larry Hesterfer | hester001law | 1903 | 5/1-9/4 | Newark Sailors | Eastern League | , | |
| Gus Hetling | hetlin001aug | 1903 | St.L.-White Seals | , | |||
| Gus Hetling | hetlin001aug | 1903 | 6/20-6/23 | Iola Gaslighters | Missouri Valley League | , | |
| Heubert | heuber000--- | 1903 | 5/8 | Nashville Volunteers | Southern Association | , | |
| Ernie Heusser | heusse000ern | 1903 | +5/3+ | Salt Lake City UT | Independent | , | |
| Ernie Heusser | heusse000ern | 1903 | +8/30+ | Eureka UT | Independent | , | |
| Mike Heydon | heydon001mic | 1903 | 4/22-9/13 | Indianapolis Indians | American Association | , | |
| Charles Heyman | heyman001c-- | 1903 | Anderson/Grand Rapids Orphans | Central League | Anderson, | ||
| Charles Heyman | heyman001c-- | 1903 | +9/13+ | Alliance OH | Independent | , | |
| Hibbard | hibbar000--- | 1903 | +6/6+ | Los Angeles | Pacific National League | , | |
| Eddie Hickey | hickey001edw | 1903 | 4/30-9/17 | Omaha Indians | Western League | , | |
| Jack Hickey | hickey002joh | 1903 | 10 g. | Seattle Siwashes | Pacific Coast League | , | |
| Jack Hickey | hickey002joh | 1903 | 5/3- | 38 g. | Seattle Chinooks | Pacific National League | , |
| Mike Hickey | hickey001mik | 1903 | 5/4-9/12 | Lowell Tigers | New England League | , | |
| Walter Hickey | hickey001wal | 1903 | 98 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| William Hickey | hickey005wil | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Hickman | hickma008--- | 1903 | 11 g. | Brewton | Interstate League | , | |
| Charlie Hickman | hickma004cha | 1903 | 131 g. | Cleveland | American League | Cleveland, OH | |
| Rowe Hicks | hicks-001row | 1903 | Rich.-Brownies | Twin City League | , | ||
| Jacob Hier | 1903 | Springfield Midgets | Missouri Valley League | , | |||
| Higgins | higgin027--- | 1903 | 6/23-6/29 | Haverhill Hustlers | New England League | , | |
| Higgins | higgin002cha | 1903 | Crookston Crooks | Northern League | , | ||
| Charles Higgins | higgin002cha | 1903 | 6/13-9/8 | Crookston Crooks | Northern League | , | |
| Charles Hilbert | hilber000--- | 1903 | York-Penn Park | Independent | , | ||
| George Hildebrand | hildeb002geo | 1903 | 184 g. | Sacramento Senators | Pacific Coast League | , | |
| Hill | hill--066--- | 1903 | 7/8 | Springfield Ponies | Connecticut League | , | |
| Belden Hill | hill--003bel | 1903 | 102 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| David Hill | 1903 | 5/9-8/1 | Umpire | Connecticut League | , | ||
| Hugh Hill | hill--001hug | 1903 | 5/1 | Cleveland | American League | Cleveland, OH | |
| Hugh Hill | hill--001hug | 1903 | 5/18-6/16,6/30 | Nashville Volunteers | Southern Association | , | |
| Hugh Hill | hill--001hug | 1903 | 6/26, +7/22 | Huntsville AL | Independent | , | |
| Hugh Hill | hill--001hug | 1903 | 8/11-9/21 | Kansas City Cowboys | American Association | , | |
| Hunter Hill | hill--001hun | 1903 | 4/25-6/27 | Corsicana Oil Citys | Texas League | , | |
| Hunter Hill | hill--001hun | 1903 | 7/1- | 86 g. | St. Louis | American League | St. Louis, MO |
| Arthur Hillebrand | hilleb001art | 1903 | +8/4-8/19 | 58 g. | Los Angeles | Pacific National League | , |
| Arthur Hillebrand | hilleb001art | 1903 | Princeton Univ. | College | , | ||
| Clarence Hillebrand | 1903 | Princeton Univ. | College | , | |||
| Homer Hillebrand | hilleb001hom | 1903 | 6/7-8/19 | Los Angeles | Pacific National League | , | |
| Homer Hillebrand | hilleb001hom | 1903 | 3 g. | Oakland Oaks | Pacific Coast League | , | |
| Charles Hiller | 1903 | +4/30+ | Weir City Browns | Independent | , | ||
| Ed Hilley | hilley001edw | 1903 | 5/8-9/9 | Utica Pent-Ups | New York State League | , | |
| Ed Hilley | hilley001edw | 1903 | 9/29 | Philadelphia | American League | Philadelphia, PA | |
| Jack Himes | himes-001joh | 1903 | 120 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Bill Hinchman | hinchm001wil | 1903 | 8/5-9/20 | Ilion Typewriters | New York State League | , | |
| Harry Hinchman | hinchm001har | 1903 | 5/8-9/20 | Ilion Typewriters | New York State League | , | |
| Hines | hines-034--- | 1903 | 7/6-7/8 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Hines | hines-040--- | 1903 | 7/7 | Iola Gaslighters | Missouri Valley League | , | |
| Hunkey Hines | hines-001hun | 1903 | 105 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Ray Hines | hines-001ray | 1903 | 5/9-5/17 | South Bend Greens | Central League | , | |
| John Hinkle | 1903 | 5/8-5/10 | Umpire | Missouri Valley League | , | ||
| John Hinton | hinton001joh | 1903 | Altoona PA | Independent | , | ||
| Arthur Hippert | hipper001gar | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Arthur Hippert | hipper001gar | 1903 | 5/22-6/12 | Houston Buffaloes | South Texas League | , | |
| Arthur Hippert | hipper001gar | 1903 | 6/15-6/29 | San Antonio Bronchos | South Texas League | , | |
| Arthur Hippert | hipper001gar | 1903 | 7/26 | Fort Worth Panthers | Texas League | , | |
| Bert Hise | hise--001ber | 1903 | 4/28-8/25 | Corsicana Oil Citys | Texas League | , | |
| Hisey | hisey-002--- | 1903 | Miles City MT | Independent | , | ||
| Hitchcroft | hitchc002--- | 1903 | 8/12-91/6 | Dayton Veterans | Central League | , | |
| Roy Hitt | hitt--001roy | 1903 | 3 g. | Oakland Oaks | Pacific Coast League | , | |
| Martin Hoag | hoag--001mar | 1903 | 15 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Martin Hoag | hoag--001mar | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | ||
| Hobbs | hobbs-009--- | 1903 | 5/20 | Dayton Veterans | Central League | , | |
| Frank Hobbs | hobbs-001fra | 1903 | Shenandoah IA | Independent | , | ||
| Hobgood | hobgoo000--- | 1903 | +3/24-4/9+ | Wake Forest | College | , | |
| Carson Hodge | hodge-001car | 1903 | 5/9-9/12 | Meriden Silverites | Connecticut League | , | |
| Carson Hodge | hodge-001car | 1903 | 9/15-9/24 | Newark Sailors | Eastern League | , | |
| Gerry Hodge | hodge-001ger | 1903 | 5/10-9/6 | Olympia Senators | Southwest Washington League | , | |
| George Hodson | hodson002geo | 1903 | 50 g. | San Francisco Seals | Pacific Coast League | , | |
| Ike Hoepple | hoeppl000ike | 1903 | Bancroft Browns | Independent | , | ||
| Ike Hoepple | hoeppl000ike | 1903 | 8/- | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | |
| Augie Hoff | hoff--001aug | 1903 | 5/25-9/16 | Dayton Veterans | Central League | , | |
| Bill Hoffer | hoffer003wil | 1903 | 4/28-9/13 | Des Moines Undertakers | Western League | , | |
| Danny Hoffman | hoffma001dan | 1903 | 4/20 - | 74 g. | Philadelphia | American League | Philadelphia, PA |
| Danny Hoffman | hoffma001dan | 1903 | 7/11-7/17 | Toledo Mud Hens | American Association | , | |
| Fred Hoffman | hoffma001fre | 1903 | 25 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Izzy Hoffman | hoffma004har | 1903 | 5/1-5/11 | Concord Marines | New England League | , | |
| Izzy Hoffman | hoffma004har | 1903 | Wilmington DE | Independent | , | ||
| Larry Hoffman | hoffma001law | 1903 | 5/7-9/12 | Meriden Silverites | Connecticut League | , | |
| Jesse Hoffmeister | hoffme002jes | 1903 | 4/25-5/5 | Minneapolis Millers | American Association | , | |
| Jesse Hoffmeister | hoffme002jes | 1903 | 5/20-9/8 | Crookston Crooks | Northern League | , | |
| Solly Hofman | hofman001art | 1903 | 7/28- | 3 g. | Pittsburgh | National League | Pittsburgh, PA |
| Hogan | hogan-006--- | 1903 | +5/28-6/14 | Walla Walla | Inland Empire League | , | |
| Hogan | hogan-006--- | 1903 | 7/19-8/23 | Olympia Senators | Southwest Washington League | , | |
| Harry Hogan | 1903 | Notre Dame U. | College | , | |||
| Harry Hogan | 1903 | FtWa-Nationals | Independent | , | |||
| James Hogan | hogan-004jam | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Wallace Hogan | hogan-002wal | 1903 | 145 g. | Sacramento Senators | Pacific Coast League | , | |
| Bill Hogg | hogg--002wil | 1903 | 4/14-6/13 | Seattle Chinooks | Pacific National League | , | |
| Bill Hogg | hogg--002wil | 1903 | +6/28-7/4+ | 12 g. | Portland Browns | Pacific Coast League | , |
| Bill Hogg | hogg--002wil | 1903 | 8/2-10/3 | Spokane Indians | Pacific National League | , | |
| George Hogreiver | hogrie001geo | 1903 | 4/22-9/20 | Indianapolis Indians | American Association | , | |
| Charles Hogsett | hogset001cha | 1903 | 7/14-7/15 | Fort Worth Panthers | Texas League | , | |
| Bradley Hogue | hogue-001b-- | 1903 | 216 ab | Augusta GA | Independent | , | |
| Walter Holcomb | holcom001wal | 1903 | Oelwein IA | Independent | , | ||
| Howard Holland | hollan001how | 1903 | Columbia SC | Independent | , | ||
| Jack Holland | hollan004joh | 1903 | 4/16-8/16 | Tacoma Tigers | Pacific National League | , | |
| Jack Holland | hollan004joh | 1903 | 8/30 | Centralia Midgets | Southwest Washington League | , | |
| James Holliday | hollid001jam | 1903 | 8/9-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Wallace Hollingsworth | hollin001wal | 1903 | 4 g. | Los Angeles Angels | Pacific Coast League | , | |
| Wallace Hollingsworth | hollin001wal | 1903 | 4/14- | 75 g. | Los Angeles | Pacific National League | , |
| Wallace Hollingsworth | hollin001wal | 1903 | 7/5 | Aberdeen Pippins | Southwest Washington League | , | |
| Wallace Hollingsworth | hollin001wal | 1903 | -7/21 | Seattle Chinooks | Pacific National League | , | |
| Wallace Hollingsworth | hollin001wal | 1903 | 97 g. | Portland Browns | Pacific Coast League | , | |
| Harvey Hollis | hollis001har | 1903 | no g. | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Harvey Hollis | hollis001har | 1903 | Homestead PA | Independent | , | ||
| Harvey Hollis | hollis001har | 1903 | 41 g. | Altoona PA | Independent | , | |
| Ed Holly | holly-002edw | 1903 | 4/28-9/17 | Peoria Distillers | Western League | , | |
| Holmes | holmes038--- | 1903 | 5/11-5/13 | Terre Haute Hottentots | Central League | , | |
| Holmes | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | |||
| Clarence Holmes | holmes001cla | 1903 | 25 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Ducky Holmes | holmes003jam | 1903 | 21 g. | Washington | American League | Washington, DC | |
| Ducky Holmes | holmes003jam | 1903 | 86 g. | Chicago | American League | Chicago, IL | |
| Fred Holmes | holmes001fre | 1903 | 6/6-7/8 | Terre Haute Hottentots | Central League | , | |
| Fred Holmes | holmes001fre | 1903 | 8/23 | New York | American League | New York, NY | |
| Jim Holmes | holmes002jam | 1903 | 5/15-5/16 | Nashville Volunteers | Southern Association | , | |
| Jim Holmes | holmes002jam | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| Scott Holmes | holmes002jam | 1903 | Illinois-Indiana-Iowa League | , | |||
| Holt | holt--015--- | 1903 | 6/25 | Fort Scott Giants | Missouri Valley League | , | |
| Earl Holt | holt--001ear | 1903 | U. North Carolina | College | , | ||
| Earl Holt | holt--001ear | 1903 | Augusta GA | Independent | , | ||
| Pearl Holycross | holycr001pea | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Frank Homer | 1903 | Fort Scott Giants | Missouri Valley League | , | |||
| Guy Hood | hood--006--- | 1903 | +6/11+ | Linc.-Bankers | LincCity | , | |
| Buck Hooker | hooker001wil | 1903 | - 4/29 | 2 g. | Cincinnati | National League | Cincinnati, OH |
| Buck Hooker | hooker001wil | 1903 | 5/13- | Concord Marines | New England League | , | |
| Buck Hooker | hooker001wil | 1903 | -9/12 | Lowell Tigers | New England League | , | |
| Ernest Hooker | hooker001e-- | 1903 | 5/8-9/15 | Buffalo Bisons | Eastern League | , | |
| Kirby Hoon | hoon--001kir | 1903 | 7/23 | Helena Senators | Pacific National League | , | |
| Sam Hope | hope--001sam | 1903 | 5/5-5/13 | Rochester Bronchos | Eastern League | , | |
| Sam Hope | hope--001sam | 1903 | 6/5-8/13 | New Haven Blues | Connecticut League | , | |
| Bill Hopke | hopke-001wil | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| Hopkins | hopkin025--- | 1903 | +5/26-7/15 | Sioux City Soos | Iowa-South Dakota League | , | |
| Hopkins | hopkin025--- | 1903 | +7/26+ | Umpire | Iowa-South Dakota League | , | |
| Hopkins | hopkin025--- | 1903 | 8/11+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Lee Hopkins | hopkin001leo | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| Lee Hopkins | hopkin001leo | 1903 | Clinton IL | Independent | , | ||
| Sis Hopkins | hopkin002a-- | 1903 | 4/29-6/3 | Montgomery Black Sox | Southern Association | , | |
| Sis Hopkins | hopkin002a-- | 1903 | 6/11-8/13 | New Orleans Pelicans | Southern Association | , | |
| Mt. Shasta Horn | horn--001mt- | 1903 | 1 g. | Sacramento Senators | Pacific Coast League | , | |
| William Horn | horn--003wil | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| William Horn | horn--001cas | 1903 | 6/8-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Hornbuckle | hornbu006--- | 1903 | 7/23-8/1 | Rome Romans | Alabama-Georgia League | , | |
| Hornshell | hornsh000--- | 1903 | 5/28 | Springfield Midgets | Missouri Valley League | , | |
| William Horrell | 1903 | Salina-Invincibles | Independent | , | |||
| Elmer Horton | horton002elm | 1903 | 5/8-9/20 | Utica Pent-Ups | New York State League | , | |
| Harry Horton | horton002har | 1903 | 6/20-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Hosington | hosing000--- | 1903 | 7/7 | Joplin Miners | Missouri Valley League | , | |
| Wilson Hosmer | hosmer002wil | 1903 | 29 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Dennis Houle | houle-001den | 1903 | 6/22-9/12 | Umpire | Connecticut League | , | |
| John House | house-001joh | 1903 | 6/23-8/2+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Ed Householder | househ001edw | 1903 | 4/17-4/30 | Brooklyn | National League | Brooklyn, NY | |
| Ed Householder | househ001edw | 1903 | +6/5-8/19 | Los Angeles | Pacific National League | , | |
| Ed Householder | househ001edw | 1903 | 9/7-9/19 | Little Rock Travelers | Southern Association | , | |
| Lefty Houtz | houtz-001fre | 1903 | 4/14-8/16 | San Francisco Pirates | Pacific National League | , | |
| Howard | howard001w-- | 1903 | 6/11-8/3 | Rochester Bronchos | Eastern League | , | |
| Benjamin Howard | howard003ben | 1903 | 6/16-7/8+ | Selma YMCA | Alabama-Georgia League | , | |
| Clinton Howard | howard000cli | 1903 | +7/9+ | Selma YMCA | Alabama-Georgia League | , | |
| Earl Howard | howard001ear | 1903 | 5/20-6/16 | Crookston Crooks | Northern League | , | |
| Earl Howard | howard001ear | 1903 | +7/24-9/8 | Superior Longshoremen | Northern League | , | |
| Ernie Howard | howard002ern | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| Leslie Howard | howard001les | 1903 | College | , | |||
| Leslie Howard | howard001les | 1903 | 7/28-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| W. Howard | howard001w-- | 1903 | 43 g. | Rochester Bronchos | Eastern League | , | |
| Howe | howe--003--- | 1903 | 8/26-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Frank Howell | howell002f-- | 1903 | 5/29-6/13 | Crookston Crooks | Northern League | , | |
| Harry Howell | howell001hen | 1903 | New York | American League | New York, NY | ||
| Harry Howell | howell001hen | 1903 | 2 g. | San Francisco Seals | Pacific Coast League | , | |
| Robert Howell | howell001rob | 1903 | 4/22-4/24 | Minneapolis Millers | American Association | , | |
| Robert Howell | howell001rob | 1903 | 5/2-5/29 | Leavenworth White Sox | Missouri Valley League | , | |
| Robert Howell | howell001rob | 1903 | 6/3-7/10+ | Springfield Midgets | Missouri Valley League | , | |
| Robert Howell | howell001rob | 1903 | +7/31+ | Wichita KS | Independent | , | |
| Billy Howells | howell005wil | 1903 | 5/20-9/8 | Fargo | Northern League | , | |
| William Howie | howie-001wil | 1903 | 5/1-6/3 | St. Joseph Saints | Western League | , | |
| William Howie | howie-001wil | 1903 | 6/19 | Colorado Springs Millionaires | Western League | , | |
| William Howie | howie-001wil | 1903 | 9/5-9/17 | St. Joseph Saints | Western League | , | |
| Billy Hoy | hoy---001wil | 1903 | 212 g. | Los Angeles Angels | Pacific Coast League | , | |
| Jimmie Hoy | hoy---002jam | 1903 | 5/21-5/30+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Jimmie Hoy | hoy---002jam | 1903 | 6/9-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Arthur Hubbard | hubbar001a-- | 1903 | Racine WI | Independent | , | ||
| Arthur Hubbard | hubbar001a-- | 1903 | no g. | Duluth Cardinals | Northern League | , | |
| Joe Hubbard | hubbar002joh | 1903 | 5/18-9/16 | Umpire | Central League | , | |
| Hubley | 1903-05 | Lafayette Col | College | , | |||
| Ed Hudson | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | |||
| I. Hudson | hudson000i-- | 1903 | 5/5-5/10 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Marvin Hudson | 1903 | 5/21- | Pulaski TN | Independent | , | ||
| Frank Huelsman | huelsm001fra | 1903 | 4/25-5/5 | Shreveport Giants | Southern Association | , | |
| Frank Huelsman | huelsm001fra | 1903 | 1 g. | Portland Browns | Pacific Coast League | , | |
| Frank Huelsman | huelsm001fra | 1903 | +5/20- | 98 g. | Spokane Indians | Pacific National League | , |
| George Huff | huff--002geo | 1903 | Chicago | National League | Chicago, IL | ||
| Tobe Huffman | hauffm001--- | 1903 | 5/3, 5/25 | Iola Gaslighters | Missouri Valley League | , | |
| Tobe Huffman | hauffm001--- | 1903 | 5/6-5/14 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Tobe Huffman | hauffm001--- | 1903 | 7/- | Wichita KS | Independent | , | |
| Tobe Huffman | hauffm001--- | 1903 | Eldorado | Independent | , | ||
| Ed Hug | hug---001edw | 1903 | 7/6 | Brooklyn | National League | Brooklyn, NY | |
| Ed Hug | hug---001edw | 1903 | 7/20-8/3 | Terre Haute Hottentots | Central League | , | |
| Miller Huggins | huggin001mil | 1903 | 4/22-9/13 | St. Paul Saints | American Association | , | |
| Hughes | hughes049--- | 1903 | 5/13 | Providence Grays | Eastern League | , | |
| Ed Hughes | hughes004edw | 1903 | 34 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| George Hughes | hughes003geo | 1903 | Lombard College | College | , | ||
| George Hughes | hughes003geo | 1903 | 93 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| George Hughes | hughes003geo | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| James Hughes | hughes004jam | 1903 | +5/28+ | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |
| James Hughes | hughes004jam | 1903 | +7/27+ | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |
| James Hughes | hughes004jam | 1903 | Huntsville | Tennessee-Alabama League | , | ||
| James Hughes | hughes004jam | 1903 | 8/24- | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |
| Jay Hughes | hughes008jam | 1903 | 60 g. | Seattle Siwashes | Pacific Coast League | , | |
| John Hughes | hughes001joh | 1903 | Saugerties | Hudson River League | , | ||
| Tom Hughes | hughes004tho | 1903 | Boston | American League | Boston, MA | ||
| William Hughes | hughes008wil | 1903 | Oklahoma City OK | Territory | , | ||
| William Hughes | hughes001wil | 1903 | Elmira-FatherMathew | Independent | , | ||
| Jim Hughey | hughey001jim | 1903 | 4/26-9/18 | Shreveport Giants | Southern Association | , | |
| Hughley | hughey001--- | 1903 | +5/3+ | Fort Douglas | Independent | , | |
| Hughley | hughey001--- | 1903 | +6/21+ | ProvoUT | Independent | , | |
| Hule | hule--001--- | 1903 | Cloquet Reserv. | Independent | , | ||
| Hule | hule--001--- | 1903 | 7/31-9/8 | Superior Longshoremen | Northern League | , | |
| Billy Hulen | hulen-001bil | 1903 | 4/14- | 120 g. | Seattle Chinooks | Pacific National League | , |
| Thomas Huling | huling001tho | 1903 | +7/19-8/11+ | Zanesville OH | Independent | , | |
| Burt Hull | 1903 | Univ. of Illinois | College | , | |||
| Burt Hull | 1903 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |||
| Fred Hulsey | hulsey000fre | 1903 | 6/15-6/17 | Anniston Invincibles | Alabama-Georgia League | , | |
| Rudy Hulswitt | hulswi001rud | 1903 | 138 g. | Philadelphia | National League | Philadelphia, PA | |
| John Hummel | hummel001joh | 1903-04 | Bloomsburg U. | College | , | ||
| John Hummel | hummel001joh | 1903 | +7/22+ | Wilmington DE | Independent | , | |
| Charles Humphrey | humphr002cha | 1903 | New London Whalers | Connecticut League | , | ||
| Charles Hunche | hunche001cha | 1903 | 4/25-7/30 | Beaumont Oil Gushers | South Texas League | , | |
| Charles Hunche | hunche001cha | 1903 | 8/27-8/28 | Houston Buffaloes | South Texas League | , | |
| Charles Hunche | hunche001cha | 1903 | 8/29-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Hunt | hunt--023--- | 1903 | 5/21-5/23 | Duluth Cardinals | Northern League | , | |
| Harry Hunt | hunt--001har | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Frederick Hunter | hunter002fre | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Dan Hupp | hupp--002dan | 1903 | +6/21+ | Waterloo IA | Independent | , | |
| Ed Hurlburt | hurlbu001edw | 1903 | 59 g. | Los Angeles Angels | Pacific Coast League | , | |
| Ed Hurlburt | hurlbu001edw | 1903 | Portland Browns | Pacific Coast League | , | ||
| Frank Hurlburt | 1903 | Springfield Midgets | Missouri Valley League | , | |||
| George Hurlburt | hurlbu001geo | 1903 | 4/14-5/30+ | Seattle Chinooks | Pacific National League | , | |
| George Hurlburt | hurlbu001geo | 1903 | +7/2+ | 64 g. | Portland Browns | Pacific Coast League | , |
| George Hurlburt | hurlbu001geo | 1903 | 3 g. | Seattle Siwashes | Pacific Coast League | , | |
| Bill Hurley | hurley003wil | 1903 | 15 g. | Seattle Siwashes | Pacific Coast League | , | |
| Bill Hurley | hurley003wil | 1903 | 4/14-10/4 | Seattle Chinooks | Pacific National League | , | |
| Jerry Hurley | hurley001jer | 1903 | 5/3-9/20 | New Orleans Pelicans | Southern Association | , | |
| Gus Hurst | hurst-010--- | 1903 | Hunt.-Erie Machinists | Independent | , | ||
| Gus Hurst | hurst-010--- | 1903 | 8/13-9/1 | Fort Wayne Railroaders | Central League | , | |
| John Hurst | hurst-001joh | 1903 | 5/23- | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Huston | huston001har | 1903 | no g. | Kansas City Blue Stockings | Western League | , | |
| Huston | huston004--- | 1903 | +8/25+ | Spokane Indians | Pacific National League | , | |
| Harry Huston | huston001har | 1903 | 6/22,7/19-9/17 | Kansas City Blue Stockings | Western League | , | |
| Harry Huston | huston001har | 1903 | 7/8-7/9 | Fort Scott Giants | Missouri Valley League | , | |
| Jack Huston | huston001jac | 1903 | 4/14-8/30 | Umpire | Pacific National League | , | |
| Edward Hutchcroft | hutchc001ed- | 1903 | 4/27-5/15 | New Orleans Pelicans | Southern Association | , | |
| Edward Hutchcroft | hutchc001ed- | 1903 | 7/25 | New Orleans Pelicans | Southern Association | , | |
| Hutchinson | hutchi016--- | 1903 | 6/26-7/1+ | Leavenworth White Sox | Missouri Valley League | , | |
| Ed Hutchinson | hutchi002ed- | 1903 | 4/14-8/16 | Tacoma Tigers | Pacific National League | , | |
| Ed Hutchinson | hutchi002ed- | 1903 | 8/23 | Olympia Senators | Southwest Washington League | , | |
| Ralph Hutchinson | hutchi002ral | 1903-05 | Univ. Texas | College | , | ||
| Ralph Hutchinson | hutchi002ral | 1903 | +5/30-8/2+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| W. M. Hutchinson | hutchi001w-- | 1903 | 4/25-7/23 | Houston Buffaloes | South Texas League | , | |
| W. M. Hutchinson | hutchi001w-- | 1903 | 7/30-8/7 | San Antonio Bronchos | South Texas League | , | |
| Amos Hutter | hutter001amo | 1903 | 5/4-5/10 | Sedalia Goldbugs | Missouri Valley League | , | |
| Amos Hutter | hutter001amo | 1903 | 5/20-5/30 | Superior Longshoremen | Northern League | , | |
| Amos Hutter | hutter001amo | 1903 | 6/10- | Crookston Crooks | Northern League | , | |
| Hutton | hutton007--- | 1903 | 5/25 | Sedalia Goldbugs | Missouri Valley League | , | |
| Elmer Hutton | hutton001--- | 1903 | , | ||||
| Slick Hutton | hutton000sli | 1903 | 5/26 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| W. A. Hutton | hutton000bil | 1903 | Medford OR | Independent | , | ||
| Will Hutton | hutton001wil | 1903 | 5/30-6/1 | Little Rock Travelers | Southern Association | , | |
| Will Hutton | hutton001wil | 1903 | 6/28-7/4 | Little Rock Travelers | Southern Association | , | |
| William Hycoop | hycoop000wil | 1903 | Clark Engine | Independent | , | ||
| William Hycoop | hycoop000wil | 1903 | +8/21+ | Kalamazoo MI | Independent | , | |
| Pat Hynes | hynes-001pat | 1903 | 237 ab | Vicksburg Hill Billies | Cotton States League | , | |
| Pat Hynes | hynes-001pat | 1903 | 9/27 | St. Louis | National League | St. Louis, MO | |
| H. B. Iba | 1903 | 6/- | Umpire | Missouri Valley League | , | ||
| Ham Iburg | iburg-001her | 1903 | 52 g. | San Francisco Seals | Pacific Coast League | , | |
| Frank Ingalls | ingall001fra | 1903 | Stockton | California State League | , | ||
| Frank Ingalls | ingall001fra | 1903 | 1 g. | Seattle Siwashes | Pacific Coast League | , | |
| Happy Iott | iott--001fre | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| Happy Iott | iott--001fre | 1903 | -9/12 | Fall River Indians | New England League | , | |
| Happy Iott | iott--001fre | 1903 | 9/16-9/18 | Cleveland | American League | Cleveland, OH | |
| Charles Irby | irby--001cha | 1903 | +5/28-6/14 | Walla Walla | Inland Empire League | , | |
| Billy Irish | 1903 | +7/29-8/16+ | Umpire | Northern League | , | ||
| Irwin | irwin-016--- | 1903 | +6/17-6/18+ | Minden | Central Nebraska League | , | |
| Arthur Irwin | irwin-001art | 1903 | 4/30-8/? | Rochester Bronchos | Eastern League | , | |
| Arthur Irwin | irwin-001art | 1903 | Toronto Maple Leafs | Eastern League | , | ||
| Charlie Irwin | irwin-001cha | 1903 | 208 g. | San Francisco Seals | Pacific Coast League | , | |
| John Irwin | irwin-001joh | 1903 | Bowdoin College | College | , | ||
| Joseph Irwin | irwin-000jos | 1903 | +6/30-7/29 | Pulaski TN | Independent | , | |
| Joseph Irwin | irwin-000jos | 1903 | +8/23+ | Pulaski | Tennessee-Alabama League | , | |
| William Irwin | irvin-001wil | 1903 | 22 g. | Kingston Colonials | Hudson River League | , | |
| William Irwin | irvin-001wil | 1903 | Saugerties | Hudson River League | , | ||
| Frank Isbell | isbell001--- | 1903 | 8/16-8/26 | Fort Worth Panthers | Texas League | , | |
| John Isbell | isbell001war | 1903 | 12 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| John Isbell | isbell001war | 1903 | 8/21-8/25+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| James Ison | 1903 | 7/19-7/29 | Dalton GA | Independent | , | ||
| Ives | ives--001geo | 1903 | 107 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Fred Jacklitsch | jackli001fre | 1903 | 60 g. | Brooklyn | National League | Brooklyn, NY | |
| Jackman | jackma001--- | 1903 | 6/11 | Iola Gaslighters | Missouri Valley League | , | |
| Charles Jackson | jackso005cha | 1903 | 5/22-8/20+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Herbert Jackson | jackso001cha | 1903 | Williamsport PA | Independent | , | ||
| James Jackson | jackso013jam | 1903 | Kingston Colonials | Hudson River League | , | ||
| Jim Jackson | jackso002jam | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| Rolla Jackson | jackso002rol | 1903 | ?-6/1 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |
| Sam Jackson | jackso002sam | 1903 | 5/16-? | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | |
| Mike Jacob | jacobs001mor | 1903 | 4/30-5/5 | Evansville River Rats | Central League | , | |
| Mike Jacob | jacobs001mor | 1903 | 5/22-9/17 | Kansas City Blue Stockings | Western League | , | |
| Jacobs | jacobs028--- | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Louis Jacobs | jacobs001lou | 1903 | 8 g. | San Francisco Seals | Pacific Coast League | , | |
| Louis Jacobs | jacobs001lou | 1903 | 1 g. | Los Angeles Angels | Pacific Coast League | , | |
| Beany Jacobson | jacobs001alb | 1903 | 22 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| James | james-033--- | 1903 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | ||
| William James | james-015wil | 1903 | Terre Haute Hottentots | Central League | , | ||
| F. O. Jamieson | 1903 | 5/6-5/31 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| F. O. Jamieson | 1903 | +8/11-8/25+ | Le Mars Blackbirds | Iowa-South Dakota League | , | ||
| Henry Jansing | jansin001hen | 1903 | 155 g. | Seattle Siwashes | Pacific Coast League | , | |
| Ferd Jarrott | jarrot001fer | 1903 | 5/20-7/25+ | Atlantic | Southwest Iowa League | , | |
| Ferd Jarrott | jarrot001fer | 1903 | +8/2-8/9+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Jack Jarvis | jarvis005wil | 1903 | 6/4-8/29 | Fort Worth Panthers | Texas League | , | |
| Rube Jarvis | jarvis000rub | 1903 | Arkansas City KS | Independent | , | ||
| Rube Jarvis | jarvis000rub | 1903 | El Reno OK | Independent | , | ||
| Rube Jarvis | jarvis000rub | 1903 | Wichita KS | Independent | , | ||
| Jeffries | jeffri005--- | 1903 | +6/15-7/14+ | Giltner | Central Nebraska League | , | |
| Charles Jeffries | jeffri001cha | 1903 | Lebanon PA | Independent | , | ||
| Fred Jenkins | jenkin002fre | 1903 | +6/18-7/24 | Minden | Central Nebraska League | , | |
| K. Jenkins | 1903 | Natchez Indians | , | ||||
| Hughie Jennings | jennin001hug | 1903 | Brooklyn | National League | Brooklyn, NY | ||
| Hughie Jennings | jennin001hug | 1903 | 7/3-8/8 | Baltimore Orioles | Eastern League | , | |
| Si Jensen | jensen001erv | 1903 | 4/16 | Butte Miners | Pacific National League | , | |
| Si Jensen | jensen001erv | 1903 | 4/25 | San Francisco Pirates | Pacific National League | , | |
| Si Jensen | jensen001erv | 1903 | +7/2+ | Ogden UT | Independent | , | |
| Si Jensen | jensen001erv | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| Joe Jerger | jerger001jos | 1903 | 28 g. | Fall River Indians | New England League | , | |
| Ed Jess | jess--001ed- | 1903 | no g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Clarence Jessup | jessup001cla | 1903 | 5/2-9/16 | Marion Oilworkers | Central League | , | |
| Jacob Jimerson | jamiso001jac | 1903 | no g. | Newark Sailors | Eastern League | , | |
| Abbie Johnson | johnso002abb | 1903 | 6/5-9/26 | Rochester Bronchos | Eastern League | , | |
| Abbie Johnson | johnso002abb | 1903 | 52 g. | Oakland Oaks | Pacific Coast League | , | |
| Guy Johnson | johnso003guy | 1903 | Kalamazoo Col | College | , | ||
| Guy Johnson | johnso003guy | 1903 | no g. | Louisville Colonels | American Association | , | |
| Harold Johnson | johnso004har | 1903 | 5/8 | Omaha Indians | Western League | , | |
| Harold Johnson | johnso004har | 1903 | +5/15+ | Helena Senators | Pacific National League | , | |
| Harold Johnson | johnso004har | 1903 | +8/6+ | Los Angeles | Pacific National League | , | |
| Harold Johnson | johnso004har | 1903 | 2 g. | Oakland Oaks | Pacific Coast League | , | |
| John Johnson | johnso001ral | 1903 | Urbana OH | Independent | , | ||
| Otis Johnson | johnso001oti | 1903 | 5/8-8/25 | Dallas Giants | Texas League | , | |
| Bill Johnston | johnst004wil | 1903 | 5/11-7/4 | Nashville Volunteers | Southern Association | , | |
| Bill Johnston | johnst004wil | 1903 | 8/12-9/19 | Nashville Volunteers | Southern Association | , | |
| Jones | jones-201--- | 1903 | 6/30-7/13 | Leavenworth White Sox | Missouri Valley League | , | |
| Jones | jones-190--- | 1903 | 6/24 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Alex Jones | jones-002ale | 1903 | -5/16 | 2 g. | Detroit | American League | Detroit, MI |
| Alex Jones | jones-002ale | 1903 | 5/29-7/29 | Providence Grays | Eastern League | , | |
| Alex Jones | jones-002ale | 1903 | 8/19-9/25 | Buffalo Bisons | Eastern League | , | |
| Alf Jones | jones-001alf | 1903 | +6/17-9/7+ | Huntsville | Tennessee-Alabama League | , | |
| Bud Jones | jones-131--- | 1903 | 6/23-8/30 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Charles Jones | jones-003w-- | 1903 | , | ||||
| Charlie Jones | jones-005cha | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Cowboy Jones | jones-003alb | 1903 | 4/30-9/13 | Colorado Springs Millionaires | Western League | , | |
| D. W. Jones | jones-002d-- | 1903 | no g. | Dayton Veterans | Central League | , | |
| Davy Jones | jones-005dav | 1903 | Chicago | National League | Chicago, IL | ||
| Evarts Jones | jones-002eva | 1903 | no g. | Kansas City Cowboys | American Association | , | |
| F. Jones | jones-000f-- | 1903 | 5/10 | Joplin Miners | Missouri Valley League | , | |
| James Jones | jones-031jam | 1903 | 5/11-5/18 | Sedalia Goldbugs | Missouri Valley League | , | |
| Jim Jones | jones-022jam | 1903 | 4/22-8/11 | Indianapolis Indians | American Association | , | |
| Jim Jones | jones-022jam | 1903 | 8/15-9/20 | Albany Senators | New York State League | , | |
| Oscar Jones | jones-002osc | 1903 | Brooklyn | National League | Brooklyn, NY | ||
| Oscar Jones | jones-002osc | 1903 | 1 g. | Los Angeles Angels | Pacific Coast League | , | |
| Oscar Jones | jones-002osc | 1903 | 1 g. | Portland Browns | Pacific Coast League | , | |
| Paul Jones | jones-013pau | 1903 | 7/8 | Selma YMCA | Alabama-Georgia League | , | |
| R. Jones | jones-008r-- | 1903 | 5/4-6/23 | Joplin Miners | Missouri Valley League | , | |
| Ross Jones | jones-003ros | 1903 | no g. | Peoria Distillers | Western League | , | |
| Ross Jones | jones-003w-- | 1903 | 44 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Tom Jones | jones-002tho | 1903 | 4/30-9/26 | Baltimore Orioles | Eastern League | , | |
| Wallace Jones | jones-001wal | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Harry Jope | jope--001hen | 1903 | 5/7-9/12 | New Haven Blues | Connecticut League | , | |
| Charlie Jordan | jordan003cha | 1903 | Camden NJ | Independent | , | ||
| Charlie Jordan | jordan003cha | 1903 | 6/22-9/12 | Lawrence Colts | New England League | , | |
| Dutch Jordan | jordan001ado | 1903 | Binghamton Bingoes | New York State League | , | ||
| Dutch Jordan | jordan001ado | 1903 | 4/25- | 78 g. | Brooklyn | National League | Brooklyn, NY |
| Mike Jordan | jordan001mik | 1903 | 7/29-8/22 | Umpire | New England League | , | |
| Slats Jordan | jordan001cla | 1903 | 5/8-5/27 | Albany Senators | New York State League | , | |
| Theodore Jordan | jordan000the | 1903 | 5/4 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Tim Jordan | jordan002tim | 1903 | 2 g. | New York | American League | New York, NY | |
| Tim Jordan | jordan002tim | 1903 | 5/1-9/12 | Nashua | New England League | , | |
| George Josslyn | jossly001geo | 1903 | 5/2-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| George Josslyn | jossly001geo | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Michael Joyce | joyce-002mic | 1903 | 5/1-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Michael Joyce | joyce-002mic | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| F. F. Joyner | joyner000ff- | 1903 | 5/15-5/26 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Frank Jude | jude--001fra | 1903 | Carlisle Indian | College | , | ||
| Bert Julian | julian000ber | 1903 | 5/22-6/10 | Fargo | Northern League | , | |
| T. A. Jump | 1903 | 7/17-7/25 | Umpire | Central League | , | ||
| Edward Justice | justic001edw | 1903 | 6/19-6/30 | Terre Haute Hottentots | Central League | , | |
| Edward Justice | justic001edw | 1903 | 7/8 | Columbus Senators | American Association | , | |
| Bob Kahl | kahl--001rob | 1903 | 5/2-5/4+ | Joplin Miners | Missouri Valley League | , | |
| Nick Kahl | kahl--001nic | 1903 | 4/28-8/22 | Kansas City Blue Stockings | Western League | , | |
| Mike Kahoe | kahoe-001mic | 1903 | 77 g. | St. Louis | American League | St. Louis, MO | |
| Kain | kain--003--- | 1903 | 4/30 | Evansville River Rats | Central League | , | |
| Charles Kain | kain--001cha | 1903 | 4/30-8/3 | Wheeling Stogies | Central League | , | |
| Nicholas Kaiser | kaiser001nic | 1903 | Calumet MI | Independent | , | ||
| John Kalahan | kalaha001joh | 1903 | 9/29 | Philadelphia | American League | Philadelphia, PA | |
| George Kalkhoff | kalkho002geo | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| Ambrose Kane | kane--001amb | 1903 | 5/4-9/12 | Concord Marines | New England League | , | |
| Billy Kane | kane--002wil | 1903 | 4/14-7/19+ | Butte Miners | Pacific National League | , | |
| Harry Kane | kane--001har | 1903 | 5/3-9/7 | Springfield Midgets | Missouri Valley League | , | |
| Harry Kane | kane--001har | 1903 | 3 g. | Detroit | American League | Detroit, MI | |
| Jerry Kane | kane--001jer | 1903 | 4/14-4/27+ | Spokane Indians | Pacific National League | , | |
| Jerry Kane | kane--001jer | 1903 | +6/4-6/14 | Dayton | Inland Empire League | , | |
| Jerry Kane | kane--001jer | 1903 | Chemara OR | Independent | , | ||
| John Kane | kane--002joh | 1903 | 5/2-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| John Kane | kane--004fra | 1903 | Amherst Col. | College | , | ||
| John Kane | kane--004fra | 1903 | 7/5-7/22 | Toledo Mud Hens | American Association | , | |
| John Kane | kane--004fra | 1903 | 8/9-9/11 | New Haven Blues | Connecticut League | , | |
| William Kane | kane--003wil | 1903 | 5/1-9/1 | Manchester | New England League | , | |
| Jay Kanzler | kanzle001jay | 1903 | 4/27-7/1 | Montgomery Black Sox | Southern Association | , | |
| Jay Kanzler | kanzle001jay | 1903 | 7/8-9/20 | Birmingham Barons | Southern Association | , | |
| Elias Kaphan | kaphan001eli | 1903 | Stockton | California State League | , | ||
| Elias Kaphan | kaphan001eli | 1903 | 7/9-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Henry Karsten | karste001hen | 1903 | U. Michigan | College | , | ||
| Jack Katoll | katoll001joh | 1903 | 5/7-8/11 | Minneapolis Millers | American Association | , | |
| Phil Kavanaugh | kavana001phi | 1903 | St.L.-Kerns | St. Louis Trolley League | , | ||
| John Keady | keady-001j-- | 1903 | Dartmouth | College | , | ||
| John Keady | keady-001j-- | 1903 | Fabyans NH | Independent | , | ||
| William Keane | keane-002wil | 1903 | Fordham Col | College | , | ||
| William Keane | keane-002wil | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| William Keane | keane-002wil | 1903 | 6/20-6/22 | Hartford Senators | Connecticut League | , | |
| William Keane | keane-002wil | 1903 | 6/24-9/11 | New London Whalers | Connecticut League | , | |
| William Keane | 1903 | +3/29+ | Georgetown U. | College | , | ||
| John Kearney | kearne000jac | 1903 | 2 g. | Mobile | Interstate League | , | |
| John Kearney | kearne000jac | 1903 | Newberry MI | Independent | , | ||
| George Keas | keas--001geo | 1903 | 5/21-8/16 | Sioux City Soos | Iowa-South Dakota League | , | |
| Jack Keavin | 1903 | St. Bonaventure | College | , | |||
| Jack Keavin | 1903 | Elmira-FatherMathew | Independent | , | |||
| Bobby Keefe | keefe-001rob | 1903 | 38 g. | Sacramento Senators | Pacific Coast League | , | |
| George Keefe | 1903 | Lancaster | Pennsylvania State League | , | |||
| John Keefe | 1903 | 5/1-9/19 | Umpire | Southern Association | , | ||
| Pat Keefe | keefe-001pat | 1903 | 6/26-7/5 | Ilion Typewriters | New York State League | , | |
| Pat Keefe | keefe-001pat | 1903 | Burlington | Northern New York League | , | ||
| Tim Keefe | keefe-001tim | 1903 | 5/20-5/30 | Superior Longshoremen | Northern League | , | |
| Thomas Keeler | keeler002--- | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Jack Keenan | keenan001kid | 1903 | 4/28-8/4 | Birmingham Barons | Southern Association | , | |
| Joe Keenan | keenan001jos | 1903 | 4/25-6/18 | Shreveport Giants | Southern Association | , | |
| Joe Keenan | keenan001jos | 1903 | 7/19-7/26 | Shreveport Giants | Southern Association | , | |
| Joe Keenan | keenan001jos | 1903 | 8/3-9/20 | New Orleans Pelicans | Southern Association | , | |
| James Kehoe | kehoe-002jim | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| Bill Keister | keiste001wil | 1903 | -8/25 | 100 g. | Philadelphia | National League | Philadelphia, PA |
| James Keith | keith-001buc | 1903 | 5/21-6/9 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| George Kelb | kelb--002geo | 1903 | 5/1-5/27 | Shreveport Giants | Southern Association | , | |
| George Kelb | kelb--002geo | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| George Kelb | kelb--002geo | 1903 | 8/27-9/14 | Shreveport Giants | Southern Association | , | |
| Charles Kelcher | 1903 | Lebanon | Pennsylvania State League | , | |||
| William Keliher | 1903 | 5/19-6/8 | Umpire | New England League | , | ||
| Hugh Kellackey | kellac001hug | 1903 | 4/30-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Hugh Kellackey | kellac001hug | 1903 | 7/20-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Frank Kellar | kellar001fra | 1903 | 68 ab | Vicksburg Hill Billies | Cotton States League | , | |
| Frank Kellar | kellar001fra | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Frank Kellar | kellar001fra | 1903 | Natchez Indians | Cotton States League | , | ||
| Frank Kellar | kellar001fra | 1903 | Greenville Grays | Cotton States League | , | ||
| James Keller | keller001jam | 1903 | +7/5-7/8+ | Leavenworth White Sox | Missouri Valley League | , | |
| Kelley | kelley039--- | 1903 | Hartford Senators | Connecticut League | , | ||
| Bill Kelley | kelley006wil | 1903 | 5/20-9/8 | Winnipeg Maroons | Northern League | , | |
| H. A. Kelley | 1903 | Greenville Grays | Cotton States League | , | |||
| Joe Kelley | kelley002jos | 1903 | Cincinnati | National League | Cincinnati, OH | ||
| John Kelley | kelley004joh | 1903 | 5/1-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| John Kelley | kelley004joh | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Mike Kelley | kelley002mic | 1903 | 4/22-9/4 | St. Paul Saints | American Association | , | |
| W. Kelley | kelley039--- | 1903 | 5/7-7/15 | Hartford Senators | Connecticut League | , | |
| William Kelley | kelley012wil | 1903 | 5/1-5/2 | Lowell Tigers | New England League | , | |
| Win Kellum | kellum001win | 1903 | 4/22-9/13 | Indianapolis Indians | American Association | , | |
| Kelly | kelly-047--- | 1903 | Knox | Independent | , | ||
| Kelly | kelly-047--- | 1903 | +7/13-7/31+ | Fargo | Northern League | , | |
| Albert Kelly | kelly-001alb | 1903 | 58 g. | San Francisco Seals | Pacific Coast League | , | |
| Billy Kelly | kelly-004wil | 1903 | 4/14- | 43 g. | Seattle Chinooks | Pacific National League | , |
| Billy Kelly | kelly-004wil | 1903 | +5/28-5/29+ | Tacoma Tigers | Pacific National League | , | |
| Billy Kelly | kelly-004wil | 1903 | 6/7- | Helena Senators | Pacific National League | , | |
| George Kelly | kelly-005geo | 1903 | , | ||||
| H. O. Kelly | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | ||
| H. O. Kelly | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | ||
| John Kelly | 1903 | 4/28-9/17 | Umpire | Western League | , | ||
| John Kelly | kelly-003joh | 1903 | 5/20-9/26 | Baltimore Orioles | Eastern League | , | |
| Lewis Kelly | kelly-000lew | 1903 | 5/27-6/10 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Matthew Kelly | kelly-001mat | 1903 | 5 g. | Mobile | Interstate League | , | |
| Speed Kelly | kelly-002rob | 1903-04 | U. of Chicago | College | , | ||
| Speed Kelly | kelly-002rob | 1903-04 | Purdue Univ. | College | , | ||
| Thomas Kelly | kelly-001tho | 1903 | Oakland Reliance | California State League | , | ||
| Thomas Kelly | kelly-001tho | 1903 | Stockton | California State League | , | ||
| Thomas Kelly | kelly-001tho | 1903 | 4/16-6/12+ | Butte Miners | Pacific National League | , | |
| Thomas Kelly | kelly-001tho | 1903 | +7/15+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Thomas Kelly | 1903 | 4/30-9/26 | Umpire | Eastern League | , | ||
| W. J. Kelly | kelly-000wj- | 1903 | 8/14-8/24 | Omaha Indians | Western League | , | |
| Bill Kemmer | kemmer001wil | 1903 | 4/28-9/17 | St. Joseph Saints | Western League | , | |
| James Kenefick | kenefi001jam | 1903 | 5/27-6/7 | Springfield Ponies | Connecticut League | , | |
| James Kenefick | kenefi001jam | 1903 | 7/7-8/22 | Hartford Senators | Connecticut League | , | |
| Ed Kenna | kenna-004edw | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| William Kenneally | kennea001wil | 1903 | Oakland Heeseman | California State League | , | ||
| William Kenneally | kennea001wil | 1903 | Oakland Reliance | California State League | , | ||
| William Kenneally | kennea001wil | 1903 | Petaluma | California State League | , | ||
| William Kenneally | kennea001wil | 1903 | Duluth Cardinals | Northern League | , | ||
| Kennedy | kenned039--- | 1903 | 5/31-6/18 | Dallas Giants | Texas League | , | |
| Kennedy | kenned039--- | 1903 | 6/22-7/6 | Galveston Sand Crabs | South Texas League | , | |
| Kennedy | kenned056--- | 1903 | Petaluma | California State League | , | ||
| Albert Kennedy | kenned002alb | 1903 | 38 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Albert Kennedy | kenned002alb | 1903 | 6/8-7/24 | McCook | Central Nebraska League | , | |
| Brickyard Kennedy | kenned005wil | 1903 | Wheeling Stogies | Central League | , | ||
| Brickyard Kennedy | kenned005wil | 1903 | -9/23 | 23 g. | Pittsburgh | National League | Pittsburgh, PA |
| Charles Kennedy | kenned001cha | 1903 | 5/7-9/12 | Umpire | Connecticut League | , | |
| Ira Kennedy | kenned000ira | 1903 | 4/27-5/2 | Houston Buffaloes | South Texas League | , | |
| Ira Kennedy | kenned000ira | 1903 | 5/13-6/12 | Beaumont Oil Gushers | South Texas League | , | |
| Ira Kennedy | kenned039--- | 1903 | Dallas Giants | Texas League | , | ||
| Jack Kennedy | kenned001joh | 1903 | no g. | Indianapolis Indians | American Association | , | |
| Jack Kennedy | kenned001joh | 1903 | no g. | Utica Pent-Ups | New York State League | , | |
| Jack Kennedy | kenned001joh | 1903 | 98 ab | Baton Rouge Red Sticks | Cotton States League | , | |
| James Kennedy | kenned006jam | 1903 | 7/27-9/12 | Hartford Senators | Connecticut League | , | |
| John Kennedy | kenned011joh | 1903 | 5/2-6/16 | Atlanta Crackers | Southern Association | , | |
| John Kennedy | kenned002alb | 1903 | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | ||
| Louis Kennedy | kenned001lou | 1903 | 19 g. | Seattle Siwashes | Pacific Coast League | , | |
| Robert Kennedy | kenned004rob | 1903 | 8/14-8/25 | Birmingham Barons | Southern Association | , | |
| Sam Kennedy | kenned001sam | 1903 | 5/7-9/12 | Meriden Silverites | Connecticut League | , | |
| Sherman Kennedy | kenned001she | 1903 | 5/30-9/20 | Nashville Volunteers | Southern Association | , | |
| Tom Kennedy | 1903 | Umpire | Hudson River League | , | |||
| J. F. Kennefic | kennef000jf- | 1903 | 5/11-5/19 | Binghamton Bingoes | New York State League | , | |
| J. F. Kennefic | kennef000jf- | 1903 | +6/27+ | Hartford Senators | Connecticut League | , | |
| William Kennelly | kennel002wil | 1903 | 16 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| William Kennelly | kennel002wil | 1903 | 5/20-9/8 | Duluth Cardinals | Northern League | , | |
| John Kerin | kerin-001joh | 1903 | 5/4 | Nashua | New England League | , | |
| John Kerin | kerin-001joh | 1903 | 7/30-9/12 | Umpire | New England League | , | |
| G. J. Kernan | kernan000gj- | 1903 | 5/21-5/30 | Crookston Crooks | Northern League | , | |
| Aaron F. Kerr | kerr--001aar | 1903 | Sharon PA | Independent | , | ||
| Otto Kersten | kerste000ott | 1903 | Forsyth MO | Independent | , | ||
| Dan Kerwin | kerwin001dan | 1903 | 4/22-9/20 | Louisville Colonels | American Association | , | |
| Dan Kerwin | kerwin001dan | 1903 | 9/27 | Cincinnati | National League | Cincinnati, OH | |
| Fred Ketchum | ketchu001fre | 1903 | 4/28-9/17 | Kansas City Blue Stockings | Western League | , | |
| Buck Kieb | kieb--000buc | 1903 | Wellsville NY | Independent | , | ||
| Buck Kieb | kieb--000buc | 1903 | Buff.-No.Buffalos | Independent | , | ||
| Frank Kiefer | 1903 | 6/16-9/12 | Umpire | Central League | , | ||
| Peter Kiernan | kierna001pet | 1903 | +6/10-6/20+ | Springfield Ponies | Connecticut League | , | |
| Tom Kiernan | kierna001tho | 1903 | Natchez Indians | Cotton States League | , | ||
| George Kihm | kihm--001geo | 1903 | 4/22-9/20 | Indianapolis Indians | American Association | , | |
| Edward Kilcoyne | kilcoy001edw | 1903 | 5/5- | Lowell Tigers | New England League | , | |
| Edward Kilcoyne | kilcoy001edw | 1903 | -6/10 | Haverhill Hustlers | New England League | , | |
| Edward Kilcoyne | kilcoy001edw | 1903 | 6/17-6/20 | Norwich Reds | Connecticut League | , | |
| Edward Kilcoyne | kilcoy001edw | 1903 | +7/16+ | Pittston-Brothers | Independent | , | |
| Edward Kilcoyne | kilcoy001edw | 1903 | +8/20-9/22+ | Wilkes-Barre PA | Independent | , | |
| John Kilcoyne | 1903 | Wilkes-Barre PA | Independent | , | |||
| Henry Killeen | killee002hen | 1903 | Connecticut League | , | |||
| Red Killefer | killef001wad | 1903-07 | U. of Michigan | College | , | ||
| Frank Killen | killen002fra | 1903 | Indianapolis Indians | American Association | , | ||
| Frank Killen | killen002fra | 1903 | 6/6-9/15 | Atlanta Crackers | Southern Association | , | |
| Ed Killian | killia001edw | 1903 | 68 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Ed Killian | killia001edw | 1903 | 8/25- | 9 g. | Cleveland | American League | Cleveland, OH |
| Sid Killian | killia001sid | 1903 | Natchez Indians | Cotton States League | , | ||
| Sid Killian | killia001sid | 1903 | 7/12-8/3 | Peoria Distillers | Western League | , | |
| Edward Killilay | killil001ed- | 1903 | 6/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Edward Killilay | killil001ed- | 1903 | Leavenworth White Sox | Missouri Valley League | , | ||
| Martin Killilay | killil001mar | 1903 | 5/18-9/26 | Iola Gaslighters | Missouri Valley League | , | |
| Martin Killilay | killil001mar | 1903 | 58 g. | Iola Gaslighters | Missouri Valley League | , | |
| Robert Killilea | killil001rob | 1903 | 1 g. | Sacramento Senators | Pacific Coast League | , | |
| Peter Kilroy | kilroy001orv | 1903 | +5/18+ | St. Cloud MN | Independent | , | |
| Peter Kilroy | kilroy001orv | 1903 | 1 g. | Winnipeg Maroons | Northern League | , | |
| Edward Kincey | kincey000ted | 1903 | +6/22-7/9 | Selma YMCA | Alabama-Georgia League | , | |
| King | king--081--- | 1903 | +7/2-7/14 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WeirC, | |
| Charles King | 1903 | 5/1-7/28 | Umpire | New England League | , | ||
| Frank King | king--002fra | 1903 | 5/20- | Grand Forks Forkers | Northern League | , | |
| Frank King | king--002fra | 1903 | +7/31+ | Superior Longshoremen | Northern League | , | |
| Frank King | king--004fra | 1903 | Camden NJ | Independent | , | ||
| Howard King | king--002fra | 1903 | 5/20-5/27 | Superior Longshoremen | Northern League | , | |
| Husky King | king--002h-- | 1903 | Peoria Distillers | Western League | , | ||
| Husky King | king--002h-- | 1903 | 189 ab | Greenville Grays | Cotton States League | , | |
| Husky King | king--002h-- | 1903 | +10/13+ | El Paso NM | Independent | , | |
| Victor King | king--001vic | 1903 | 48 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Ernest Kinkead | kinkea001--- | 1903 | Johnstown PA | Independent | , | ||
| Billy Kinloch | kinloc001bil | 1903 | 93 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Billy Kinloch | kinloc001bil | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| Billy Kinloch | kinloc001bil | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| James Kinney | 1903 | 5/10-6/21 | Umpire | Central League | , | ||
| William Kinskey | kinske000wil | 1903 | 8/19 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Kirmayer/eyer | 1903 | 6/17-6/20 | Leavenworth White Sox | Missouri Valley League | , | ||
| William Kirwan | kirwan001wil | 1903 | Hornellsville NY | Independent | , | ||
| William Kirwan | kirwan001wil | 1903 | 9/4-9/10 | Binghamton Bingoes | New York State League | , | |
| Rube Kisinger | kising001cha | 1903 | -9/24 | 16 g. | Detroit | American League | Detroit, MI |
| Rube Kisinger | kising001cha | 1903 | 5/8-7/12 | Toronto Maple Leafs | Eastern League | , | |
| Frank Kitson | kitson001fra | 1903 | 36 g. | Detroit | American League | Detroit, MI | |
| Charles Kittinger | 1903 | Akron OH | Independent | , | |||
| Malachi Kittridge | kittri001mal | 1903 | 32 g. | Boston | National League | Boston, MA | |
| Malachi Kittridge | kittri001mal | 1903 | 60 g. | Washington | American League | Washington, DC | |
| Kitzmiller | kitzmi000--- | 1903 | 6/8-7/24 | Holdredge | Central Nebraska League | , | |
| Frank Klaus | klaus-001fra | 1903 | 5/21-8/15+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Frank Klaus | klaus-001fra | 1903 | 9/7-9/15 | Fort Wayne Railroaders | Central League | , | |
| Butsey Kleeman | kleema001e-- | 1903 | 8/13-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Red Kleinow | kleino001joh | 1903 | 4/23-9/19 | Toledo Mud Hens | American Association | , | |
| William Klem | klem--001bil | 1903 | 5/8-9/20 | Umpire | New York State League | , | |
| Louis Kline | kline-001l-- | 1903 | 5/20-6/6 | Duluth Cardinals | Northern League | , | |
| Louis Kline | kline-001l-- | 1903 | +8/8-9/8 | Duluth Cardinals | Northern League | , | |
| Rudy Kling | kling-001rud | 1903 | 4/30-6/17 | Terre Haute Hottentots | Central League | , | |
| Rudy Kling | kling-001rud | 1903 | 2 g. | Oakland Oaks | Pacific Coast League | , | |
| Rudy Kling | kling-001rud | 1903 | 8/5-8/8 | Evansville River Rats | Central League | , | |
| Rudy Kling | kling-001rud | 1903 | 8/15-8/21 | Colorado Springs Millionaires | Western League | , | |
| Rudy Kling | kling-001rud | 1903 | 9/11-9/14 | Evansville River Rats | Central League | , | |
| Frank Klinkhammer | klinkh001fra | 1903 | 12 g. | Seattle Siwashes | Pacific Coast League | , | |
| Frank Klinkhammer | klinkh001fra | 1903 | +8/2-8/5+ | Seattle Chinooks | Pacific National League | , | |
| William Klintworth | klintw001wil | 1903 | 9/1-9/16 | Wheeling Stogies | Central League | , | |
| Fred Klobedanz | klobed001fre | 1903 | 5/2-9/7 | Lawrence Colts | New England League | , | |
| Klock | klock-002--- | 1903 | 7/13 | Utica Pent-Ups | New York State League | , | |
| William Klock | klock-001wil | 1903 | 5/9-9/20 | Ilion Typewriters | New York State League | , | |
| Gus Klopf | klopf-001gus | 1903 | 4/14-9/29+ | Spokane Indians | Pacific National League | , | |
| O. Knapp | knapp-008--- | 1903 | 5/7-9/6 | Centralia Midgets | Southwest Washington League | , | |
| Louis Knau | knau--001lou | 1903 | 5/1-9/12 | Manchester | New England League | , | |
| Phil Knell | knell-001phi | 1903 | San Francisco | California State League | , | ||
| Phil Knell | knell-001phi | 1903 | Sacramento Senators | Pacific Coast League | , | ||
| Julius Knoll | knoll-001jul | 1903 | 4/27-9/21 | Kansas City Cowboys | American Association | , | |
| Punch Knoll | knoll-001cha | 1903 | 4/27-9/20 | Nashville Volunteers | Southern Association | , | |
| Elmer Knowlton | knowlt002elm | 1903 | 6/10-6/11 | Fargo | Northern League | , | |
| William Knupple | knuppl001wil | 1903 | 8/6 | Milwaukee Creams | Western League | , | |
| Ben Koehler | koehle001ber | 1903 | 4/27-9/20 | Atlanta Crackers | Southern Association | , | |
| Koelin | koelin000--- | 1903 | 7/17 | Grand Forks Forkers | Northern League | , | |
| Steve Kohlar | kohlar001ste | 1903 | 115 g. | Houston Buffaloes | South Texas League | , | |
| Henry Kohler | 1903 | StL.-Kerns | , | ||||
| Steve Kolar/Kohlar | kohlar001ste | 1903 | 4/25-8/31 | Houston Buffaloes | South Texas League | , | |
| Fred Kossuch | kossuc001fre | 1903 | 9/5-9/13 | Dayton Veterans | Central League | , | |
| Joe Kostal | kostal001jos | 1903 | 18 g. | Portland Browns | Pacific Coast League | , | |
| Joe Kostal | kostal001jos | 1903 | 3 g. | Seattle Siwashes | Pacific Coast League | , | |
| Joe Kostal | kostal001jos | 1903 | 9/7-9/13 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| David Kraft | kraft-001dav | 1903 | 5/2-6/10 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Kratty | kratty000--- | 1903 | 7/23 | Joplin Miners | Missouri Valley League | , | |
| Harry Krause | krause004har | 1903 | +7/31+ | Atlantic City NJ | Independent | , | |
| Harry Krause | krause004har | 1903 | +8/29-9/3+ | Brandywine PA | Independent | , | |
| Krebs | krebs-001--- | 1903 | Petaluma | California State League | , | ||
| Charles Krebs | 1903 | Manhattan Col. | College | , | |||
| Charles Krebs | 1903 | U. Virginia | College | , | |||
| Charles Krebs | 1903 | Dickinson College | College | , | |||
| Ed Krebs | krebs-001edw | 1903 | 106 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| William Kreidy | kreidy001wil | 1903 | Saugerties | Hudson River League | , | ||
| Paul Krichell | kriche001pau | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| Paul Krichell | kriche001pau | 1903 | Hudson River League | , | |||
| Krick | 1903 | 11 g. | Iowa-South Dakota League | , | |||
| Bill Krieg | krieg-001bil | 1903 | 5/16-6/20 | Umpire | Central League | , | |
| John Kroell | kroell001joh | 1903 | Louisville CO | Independent | , | ||
| Otto Krueger | kruege002art | 1903 | 80 g. | Pittsburgh | National League | Pittsburgh, PA | |
| Henry Krug | krug--001hen | 1903 | 217 g. | San Francisco Seals | Pacific Coast League | , | |
| Kruger | kruger010--- | 1903 | Yankton College | College | , | ||
| Kruger | kruger010--- | 1903 | 5/21-5/30+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Kruger | kruger010--- | 1903 | +7/31+ | Canton SD | Independent | , | |
| Art Kruger | kruger001art | 1903 | 180 g. | Oakland Oaks | Pacific Coast League | , | |
| Harry Kubitz | kubitz001har | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| Harry Kubitz | kubitz001har | 1903 | 6/29-7/22 | Grand Forks Forkers | Northern League | , | |
| Harry Kubitz | kubitz001har | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| Albert Kuhn | kuhn--001alb | 1903 | 92 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Jimmy Kuhn | kuhn--001jam | 1903 | 4/30-7/7 | Evansville River Rats | Central League | , | |
| Jimmy Kuhn | kuhn--001jam | 1903 | 7/19-9/16 | Terre Haute Hottentots | Central League | , | |
| Charlie Kuhns | kuhns-001cha | 1903 | 4/30-9/26 | Toronto Maple Leafs | Eastern League | , | |
| Frederick Kuhns | kuhns-002fre | 1903 | 7/30 | Toledo Mud Hens | American Association | , | |
| Frederick Kuhns | kuhns-002fre | 1903 | 8/14-9/8 | Concord Marines | New England League | , | |
| Arthur Kulms | 1903 | Ludington MI | Independent | , | |||
| Harry Kunkel | kunkel003har | 1903 | 6/15-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Louis Kurtz | kurtz-001lou | 1903 | 8/8-8/26 | New Orleans Pelicans | Southern Association | , | |
| Kussel | 1903 | 7/5-7/16 | Umpire | Central League | , | ||
| Grant LaBarge | labarg001gra | 1903 | 4/30-5/4 | Terre Haute Hottentots | Central League | , | |
| Grant LaBarge | labarg001gra | 1903 | 6/21-6/25 | Fort Worth Panthers | Texas League | , | |
| George LaBelle | labell001geo | 1903 | Sault Ste. Marie | , | |||
| Hank Labelle | labell001hen | 1903 | 5/2-9/12 | Nashua | New England League | , | |
| George LaChance | lachan001geo | 1903 | 141 g. | Boston | American League | Boston, MA | |
| Hi Ladd | ladd--001art | 1903 | 5/7-9/12 | Bridgeport Orators | Connecticut League | , | |
| Harry LaFrance | lafran001har | 1903 | 5/18-5/28 | Umpire | Missouri Valley League | , | |
| Harry LaFrance | lafran001har | 1903 | 6/6-6/28 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Harry LaFrance | lafran001har | 1903 | Marysville KS | Independent | , | ||
| John Lagger | lagger001joh | 1903 | 5/2-5/30 | Duluth Cardinals | Northern League | , | |
| John Lagger | lagger001joh | 1903 | 6/1-9/8 | Superior Longshoremen | Northern League | , | |
| Paul LaGrave | lagrav001pau | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| John Laird | laird-001tom | 1903 | 1 g. | Brewton | Interstate League | , | |
| Frank Lakaff | lakaff001fra | 1903 | Clinton IL | Independent | , | ||
| Frank Lakaff | lakaff001fra | 1903 | +8/2+ | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Frank Lakaff | lakaff001fra | 1903 | Clinton IL | Independent | , | ||
| Fred Lake | lake--001fre | 1903 | 5/14-9/12 | Lowell Tigers | New England League | , | |
| Bud Lally | lally-007--- | 1903 | no g. | Birmingham Barons | Southern Association | , | |
| Bud Lally | lally-003bud | 1903 | northern IN | Independent | , | ||
| Bud Lally | lally-007--- | 1903 | 8/5-9/11 | Evansville River Rats | Central League | , | |
| Bud Lally | 1903 | Monroe Hill Citys | Cotton States League | , | |||
| Dan Lally | lally-001dan | 1903 | 4/22-9/21 | Minneapolis Millers | American Association | , | |
| Lallyhan | lallyh000--- | 1903 | 5/14 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Bert Lamb | 1903 | Salina-Invincibles | Independent | , | |||
| William Lambert | lamber002wil | 1903 | 5/20-7/27 | Duluth Cardinals | Northern League | , | |
| C. Lament | lament000c-- | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Pete Lamer | lamer-001pie | 1903 | +4/26+ | Hoboken NJ | Independent | , | |
| Lampkin | lampki001doc | 1903 | 5/28-6/30+ | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Lampkin | lampki001doc | 1903 | El Paso TX | Independent | , | ||
| Lancaster | lancas004--- | 1903 | 8/18 | Haverhill Hustlers | New England League | , | |
| Ernest Landgraf | landgr001ern | 1903 | Hornellsville NY | Independent | , | ||
| William Landy | landy-001wil | 1903 | 5/13-9/12 | Hartford Senators | Connecticut League | , | |
| Lane | lane--024--- | 1903 | 9/24-9/26 | Buffalo Bisons | Eastern League | , | |
| Ed Lane | lane--001ed- | 1903 | St. Albans Col. | College | , | ||
| Ed Lane | lane--001ed- | 1903 | +5/4+ | 10 g. | Montgomery Black Sox | Interstate League | , |
| Ed Lane | lane--001ed- | 1903 | 6/-7/18 | Talladega Tigers | Alabama-Georgia League | , | |
| Ed Lane | lane--001ed- | 1903 | 9 g. | Decatur | Tennessee-Alabama League | , | |
| Lang | lang--014--- | 1903 | 99 g. | Altoona PA | Independent | , | |
| John Lang | 1903 | St. Joseph | , | ||||
| Nig Langdon | langdo001fra | 1903 | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | ||
| Nig Langdon | langdo001fra | 1903 | +8/16-9/7+ | Pana IL | Independent | , | |
| Robert Langley | langle001rob | 1903 | Stockton | California State League | , | ||
| Bob Langsford | langsf001bob | 1903 | 10 g. | Montgomery Black Sox | Interstate League | , | |
| Bob Langsford | langsf001bob | 1903 | Mobile | Interstate League | , | ||
| William Langton | langto001wil | 1903 | 5/4-9/9 | Haverhill Hustlers | New England League | , | |
| Frank LaPorte | laport002fra | 1903 | 5/2-8/13 | Buffalo Bisons | Eastern League | , | |
| Patrick Larkin | larkin001p-- | 1903 | Georgetown U. | College | , | ||
| Patrick Larkin | larkin001p-- | 1903 | Elmira NY | Independent | , | ||
| Teddy Larkin | larkin001pie | 1903 | 5/7-9/12 | Meriden Silverites | Connecticut League | , | |
| Teddy Larkin | larkin001pie | 1903 | 9/13-9/25 | Newark Sailors | Eastern League | , | |
| Sam LaRocque | larocq001sam | 1903 | Butte Miners | Pacific National League | , | ||
| Sam LaRocque | larocq001sam | 1903 | San Antonio Bronchos | South Texas League | , | ||
| Purl LaRue | 1903 | FtWa-Shamrocks | Independent | , | |||
| Purl LaRue | 1903 | 5/22-5/26 | South Bend Greens | Central League | , | ||
| Arlie Latham | latham002wal | 1903 | 5/3-8/2 | Umpire | Eastern League | , | |
| Arlie Latham | latham002wal | 1903 | 8/21-9/20 | Umpire | Southern Association | , | |
| Tacks Latimer | latime001cli | 1903 | 4/30-7/19 | Denver Grizzlies | Western League | , | |
| Tacks Latimer | latime001cli | 1903 | 21 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Michael Lattin | 1903 | +9/5-9/26+ | Balt.-Ironsides | Independent | , | ||
| Frank Lauchner | lauchn001fra | 1903 | 5/25-6/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Billy Lauder | lauder001wil | 1903 | -9/26 | 108 g. | New York | National League | New York, NY |
| George Lauder | lauder001geo | 1903 | 6/10-6/20 | New Haven Blues | Connecticut League | , | |
| Bill Lauterborn | lauter001wil | 1903 | 5/9-5/13 | Syracuse Stars | New York State League | , | |
| Bill Lauterborn | lauter001wil | 1903 | 5/22-9/20 | Binghamton Bingoes | New York State League | , | |
| Ed Lauzon | lauzon001edw | 1903 | 4/27-9/20 | Atlanta Crackers | Southern Association | , | |
| William Laval | laval-001wil | 1903 | +4/14+ | Furman Col | College | , | |
| Frank Law | law---001fra | 1903 | 5/10-7/19 | Centralia Midgets | Southwest Washington League | , | |
| Frank Law | law---001fra | 1903 | Vancouver | Independent | , | ||
| Frank Law | law---001fra | 1903 | 8/23-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Jack Law | law---001joh | 1903 | 4/25-9/19 | New Orleans Pelicans | Southern Association | , | |
| Jack Lawler | lawler003joh | 1903 | 9 g. | Los Angeles Angels | Pacific Coast League | , | |
| Jack Lawler | lawler003joh | 1903 | 4/14-8/16 | Tacoma Tigers | Pacific National League | , | |
| John Lawler | lawler001joh | 1903 | 8/11-9/12 | Huntsville | Tennessee-Alabama League | , | |
| Ed Lawlor | lawlor001ed- | 1903 | 4/27-9/20 | Birmingham Barons | Southern Association | , | |
| Jack Lawlor | lawlor001joh | 1903 | 4/30-9/26 | Newark Sailors | Eastern League | , | |
| Andy Lawrence | lawren001and | 1903 | 5/8-9/1 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Andy Lawrence | lawren001and | 1903 | 9/6-9/20 | Binghamton Bingoes | New York State League | , | |
| G. Lawrence | lawren002g-- | 1903 | 8/26-9/12 | Hartford Senators | Connecticut League | , | |
| J. C. Lawrence | 1903 | 4/30-5/31+ | Colfax | Inland Empire League | , | ||
| Mike Lawrence | lawren001mic | 1903 | 4/30-8/10 | Evansville River Rats | Central League | , | |
| Mike Lawrence | lawren001mic | 1903 | 8/16-9/16 | Marion Oilworkers | Central League | , | |
| Billy Lawson | lawson001wil | 1903 | 93 g. | Kingston Colonials | Hudson River League | , | |
| Joe Lawtner | lawtne001jos | 1903 | St.L.-Rawlings | Independent | , | ||
| Joe Lawtner | lawtne001jos | 1903 | 5/2-6/19+ | Sedalia Goldbugs | Missouri Valley League | , | |
| Joe Lawtner | lawtne001jos | 1903 | 6/27-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Al Lawton | lawton000al- | 1903 | 5/1-9/11 | Fall River Indians | New England League | , | |
| Leach | 1903 | +5/29-6/14 | Walla Walla | Inland Empire League | , | ||
| Leahy | leahy-011--- | 1903 | 5/7-5/27 | Bridgeport Orators | Connecticut League | , | |
| David Leahy | leahy-001dav | 1903 | 5/9-7/11 | New Haven Blues | Connecticut League | , | |
| David Leahy | leahy-001dav | 1903 | 7/15-7/20 | Springfield Ponies | Connecticut League | , | |
| Tom Leahy | leahy-002tho | 1903 | 147 g. | San Francisco Seals | Pacific Coast League | , | |
| Frank Leary | leary-001fra | 1903 | 6/1-9/24 | Rochester Bronchos | Eastern League | , | |
| John Lease | lease-000joh | 1903 | +6/15+ | McCook | Central Nebraska League | , | |
| John Lease | lease-000joh | 1903 | +6/24-7/11+ | Giltner | Central Nebraska League | , | |
| Roy Lease | lease-000roy | 1903 | +6/15+ | McCook | Central Nebraska League | , | |
| Roy Lease | lease-000roy | 1903 | +7/11+ | Giltner | Central Nebraska League | , | |
| Sam Leatherby | 1903 | +6/18+ | Minden NE | Independent | , | ||
| William LeCompte | lecomp001w-- | 1903 | 9/6 | Milwaukee Brewers | American Association | , | |
| William LeCompte | lecomp001w-- | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Lee | lee---063--- | 1903 | +8/31 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Carter Lee | lee---010car | 1903 | Albany | Willamette Valley | Albany, OR | ||
| George Lee | lee---001geo | 1903 | 5/12-9/12 | Concord Marines | New England League | , | |
| Granville Lee | lee---001gra | 1903 | +5/11-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Granville Lee | lee---001gra | 1903 | 8/21 | Joplin Miners | Missouri Valley League | , | |
| Jack Lee | lee---003joh | 1903 | 38 g. | Oakland Oaks | Pacific Coast League | , | |
| Jack Lee | lee---003joh | 1903 | 9/18 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Wyatt Lee | lee---001wya | 1903 | 75 g. | Washington | American League | Washington, DC | |
| Bill LeGrande | legran001w-- | 1903 | NC School | , | |||
| Bill LeGrande | legran001w-- | 1903 | Joplin Miners | Missouri Valley League | , | ||
| George Leidy | leidy-002geo | 1903 | 4/25-6/21 | New Orleans Pelicans | Southern Association | , | |
| George Leidy | leidy-002geo | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| George Leidy | leidy-002geo | 1903 | 7/31-9/20 | Umpire | Southern Association | , | |
| Lefty Leifield | leifie001alb | 1903 | Joplin Miners | Missouri Valley League | , | ||
| Leighton | leight007--- | 1903 | 7/17-7/18 | Little Rock Travelers | Southern Association | , | |
| Jim Leighton | leight001jam | 1903 | 5/27-6/15 | Birmingham Barons | Southern Association | , | |
| Jim Leighton | leight001jam | 1903 | +7/4+ | Tampa FL | Independent | , | |
| Joe Leighton | leight000joe | 1903 | 11 g. | Brewton | Interstate League | , | |
| Joe Leighton | leight000joe | 1903 | +7/4+ | Tampa FL | Independent | , | |
| Joe Leighton | leight000joe | 1903 | Anniston AL | Independent | , | ||
| Joe Leighton | leight000joe | 1903 | 8/20+ | Decatur | Tennessee-Alabama League | , | |
| Joe Leighton | leight000joe | 1903 | 8/21-9/3+ | Umpire | Tennessee-Alabama League | , | |
| Bill Leith | leith-001bil | 1903 | 5/2-5/21 | Rochester Bronchos | Eastern League | , | |
| Bill Leith | leith-001bil | 1903 | 6/9- | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Bill Leith | leith-001bil | 1903 | -9/12 | Manchester | New England League | , | |
| Harry Leitman | leitma001har | 1903 | Seattle Chinooks | Pacific National League | , | ||
| Harry Leitman | leitma001har | 1903 | San Francisco Pirates | Pacific National League | , | ||
| George Leitner | leitne001geo | 1903 | 5/1-5/17 | Des Moines Undertakers | Western League | , | |
| Harry Lemonius | lemoni000har | 1903 | 6/27-7/3 | Houston Buffaloes | South Texas League | , | |
| Carl Lempke | lempke001car | 1903 | CO Sch of Mines | College | , | ||
| Carl Lempke | lempke001car | 1903 | 5/8-9/14 | Denver Grizzlies | Western League | , | |
| Charles Leonard | leonar006cha | 1903 | 6/2-6/6 | Duluth Cardinals | Northern League | , | |
| Frank Leonard | leonar001fra | 1903 | 4/22-6/? | Columbus Senators | American Association | , | |
| John Leonard | leonar001joh | 1903 | 5/5-5/11 | Rochester Bronchos | Eastern League | , | |
| John Leonard | leonar001joh | 1903 | 5/14 | Utica Pent-Ups | New York State League | , | |
| John Leonard | leonar011joh | 1903 | 5/1-5/15 | Lowell Tigers | New England League | , | |
| William Leonard | leonar003wil | 1903 | 5/19-6/15 | Schenectady Frog Alleys | New York State League | , | |
| William Leonard | leonar003wil | 1903 | 6/22-7/7 | Binghamton Bingoes | New York State League | , | |
| George Leopold | leopol001geo | 1903 | Decatur Commodores | Illinois-Indiana-Iowa League | , | ||
| George Leopold | leopol001geo | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| George Leopold | leopol001geo | 1903 | +7/13-9/8 | Fargo | Northern League | , | |
| Pete LePine | lepine002lou | 1903 | 4/30-9/26 | Rochester Bronchos | Eastern League | , | |
| Charles LeRoi | leroi-001cha | 1903 | 5/8-9/23 | Springfield Midgets | Missouri Valley League | , | |
| Louis LeRoy | leroy-001lou | 1903 | 5/3-9/19 | Buffalo Bisons | Eastern League | , | |
| Fenner Leslie | leslie001fen | 1903 | 4/25-8/23 | Houston Buffaloes | South Texas League | , | |
| Fenner Leslie | leslie001fen | 1903 | 8/28-9/20 | Indianapolis Indians | American Association | , | |
| Harvey Leslie | leslie000har | 1903 | 5/12-5/24 | Beaumont Oil Gushers | South Texas League | , | |
| Tom Letcher | letche001tom | 1903 | 4/30-9/16 | Marion Oilworkers | Central League | , | |
| Sam Letherby | leathe001--- | 1903 | no g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Sam Letherby | leathe001--- | 1903 | +6/17-7/24 | Minden | Central Nebraska League | , | |
| Sam Letherby | leathe001--- | 1903 | +9/6+ | Hooper NE | Independent | , | |
| Rube Levy | levy--001reu | 1903 | +5/10-11/27+ | Umpire | Pacific Coast League | , | |
| Ed Lewee | lewee-001edw | 1903 | 4/22-9/21 | Kansas City Cowboys | American Association | , | |
| Mort Lewinson | 1903 | Umpire | Western League | , | |||
| Carl Lewis | lewis-001car | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Carl Lewis | lewis-001car | 1903 | 6/16-6/22 | Superior Longshoremen | Northern League | , | |
| Dudley Lewis | 1903 | 7/7- | Umpire | Kentucky-Illinois-Tennessee League | , | ||
| Earl Lewis | lewis-001ear | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| Gordon Lewis | lewis-001gor | 1903-05 | Univ. Wisconsin | College | , | ||
| Gordon Lewis | lewis-001gor | 1903 | Baraga MI | Independent | , | ||
| Phil Lewis | lewis-001phi | 1903 | Plattsburg NY | Independent | , | ||
| Phil Lewis | lewis-001phi | 1903 | Elmira | Southern Tier | , | ||
| Glenn Liebhardt | liebha002gle | 1903 | 21 g. | Los Angeles | Pacific National League | , | |
| Glenn Liebhardt | liebha002gle | 1903 | Spokane Indians | Pacific National League | , | ||
| John Lilley | 1903 | Lehigh Univ. | College | , | |||
| John Lilley | 1903 | no g. | Detroit | American League | Detroit, MI | ||
| John Lilley | 1903 | 4/30-6/30 | Rochester Bronchos | Eastern League | , | ||
| James Limric | limric001jam | 1903 | +6/7+ | Canton OH | Independent | , | |
| James Limric | limric001jam | 1903 | +9/26+ | East Akron OH | Independent | , | |
| Doc Lindberg/er | 1903 | 5/25-5/31+ | Colfax | Inland Empire League | , | ||
| Bob Lindemann | lindem002joh | 1903 | York-Penn’s Park | Independent | , | ||
| Bob Lindemann | lindem002joh | 1903 | Williamsport | , | |||
| Ernie Lindemann | lindem001ern | 1903 | +5/10+ | Hoboken NJ | Independent | , | |
| Albert Linderbeck | linder001alb | 1903 | +8/2+ | Paulding OH | Independent | , | |
| F. Lindley | lindle000f-- | 1903 | 5/28+ | Leavenworth White Sox | Missouri Valley League | , | |
| Howard Lindley | lindle001how | 1903 | +4/30+ | Weir City Browns | Independent | , | |
| Howard Lindley | lindle001how | 1903 | 5/14-6/13 | Leavenworth White Sox | Missouri Valley League | , | |
| Howard Lindley | lindle001how | 1903 | 7/24-8/2 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Harry Lindsay | lindsa001ira | 1903 | 55 g. | San Francisco Seals | Pacific Coast League | , | |
| John Lindsay | lindsa002joh | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| McVey Lindsey | 1903 | 4/30-5/29 | Anderson/Grand Rapids Orphans | Central League | Anderson, | ||
| McVey Lindsey | 1903 | 5/30-9/15 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | ||
| John Linehan | lineha000joh | 1903 | 7/17-7/29 | Haverhill Hustlers | New England League | , | |
| Perry Lipe | lipe--001per | 1903 | Greenville Grays | Cotton States League | , | ||
| Tom Lipp | lipp--001tom | 1903 | Colorado Springs Millionaires | Western League | , | ||
| Tom Lipp | lipp--001tom | 1903 | Altoona PA | Independent | , | ||
| Tom Lipp | lipp--001tom | 1903 | York-Penn Park | Independent | , | ||
| Louis Lippert | lipper001lou | 1903 | 4/22-4/28 | Minneapolis Millers | American Association | , | |
| Louis Lippert | lipper001lou | 1903 | 85 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Louis Lippert | lipper001lou | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| Louis Lippert | lipper001lou | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| Louis Lippert | lipper001lou | 1903 | Bellevue IL | Independent | , | ||
| Pete Lister | lister001mor | 1903 | 67 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Paddy Livingston | living001pat | 1903 | 6/9-6/15 | Terre Haute Hottentots | Central League | , | |
| Paddy Livingston | living001pat | 1903 | Kent OH | Independent | , | ||
| Jake Livingstone | living001jac | 1903 | Norristown | , | |||
| Jake Livingstone | living001jac | 1903 | 6/8-7/5 | Lebanon | Tri State League | , | |
| Abel Lizotte | lizott001abe | 1903 | 4/28-9/17 | Peoria Distillers | Western League | , | |
| Harry Lloyd | lloyd-002har | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Harry Lloyd | lloyd-002har | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Hans Lobert | lobert001joh | 1903 | 9/21- | 5 g. | Pittsburgh | National League | Pittsburgh, PA |
| Harry Lochhead | lochhe001rob | 1903 | 4/26-8/24 | Fort Worth Panthers | Texas League | , | |
| Lockmiller | 1903 | 4/27- | Oklahoma City | Independent | , | ||
| Frank Loehner | loehne000fra | 1903 | Bonner MT | Independent | , | ||
| David Logan | logan-001dav | 1903 | 7/8-7/11 | Nashville Volunteers | Southern Association | , | |
| David Logan | logan-001dav | 1903 | Huntsville | Tennessee-Alabama League | , | ||
| Frank Logan | logan-001f-- | 1903 | 4/25-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| Tom Logan | logan-001tho | 1903 | York | Tri State League | , | ||
| Joe Lohbeck | lohbec001jos | 1903 | 87 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Joe Lohbeck | lohbec001jos | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Pete Lohman | lohman001geo | 1903 | 90 g. | Oakland Oaks | Pacific Coast League | , | |
| Frank Lohr | lohr--001fra | 1903 | 5/21-8/30 | Sioux City Soos | Iowa-South Dakota League | , | |
| Harry Lohr | 1903 | Creston Cyclones | Southwest Iowa League | , | |||
| Harry Long | long--003har | 1903 | 5/7-9/12 | New London Whalers | Connecticut League | , | |
| Herman Long | long--001her | 1903 | 22 g. | New York | American League | New York, NY | |
| Herman Long | long--001her | 1903 | 69 g. | Detroit | American League | Detroit, MI | |
| James Long | long--001art | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Red Long | long--001nel | 1903 | 5/1-9/12 | Lawrence Colts | New England League | , | |
| Harry Longley | longle001har | 1903 | 470 ab | Pine Bluff Lumbermen | Cotton States League | , | |
| Longnecker | longan000--- | 1903 | +7/21+ | Giltner | Central Nebraska League | , | |
| William Lord | lord--001wil | 1903 | +5/25-8/15 | Harrisburg PA | Independent | , | |
| Manfred Lothrop | 1903 | No. Adams MA | Independent | , | |||
| Sylvester Loucks | loucks001syl | 1903 | 11 g. | Portland Browns | Pacific Coast League | , | |
| Sylvester Loucks | loucks001syl | 1903 | 31 g. | Tacoma Tigers | Pacific National League | , | |
| Charlie Loudenslager | louden001cha | 1903 | 5/8-9/20 | Syracuse Stars | New York State League | , | |
| Bert Lougheed | loughe001ber | 1903 | 4/30-6/14 | Dayton | Inland Empire League | , | |
| Bert Lougheed | loughe001ber | 1903 | 6/28-7/19 | Olympia Senators | Southwest Washington League | , | |
| Bert Lougheed | loughe001ber | 1903 | Everett WA | Independent | , | ||
| Love | 1903 | Vanderbilt Univ | College | , | |||
| Jackson Love | love--001jac | 1903 | Springfield Midgets | Missouri Valley League | , | ||
| Jackson Love | love--001jac | 1903 | Van Buren ARK | Independent | , | ||
| Clarence Lovell | lovell001cla | 1903 | 4/30-6/11 | Rochester Bronchos | Eastern League | , | |
| Clarence Lovell | lovell001cla | 1903 | 8/1-9/20 | Albany Senators | New York State League | , | |
| Clarence Lovell | lovell001cla | 1903 | 8/3-8/10 | Schenectady Frog Alleys | New York State League | , | |
| John Lovett | lovett001joh | 1903 | 5/22-5/26 | St. Louis | National League | St. Louis, MO | |
| John Lovett | lovett001joh | 1903 | 5/20-6/30 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Bobby Lowe | lowe--002rob | 1903 | Chicago | National League | Chicago, IL | ||
| Bobby Lowe | lowe--002rob | 1903 | 7/28-9/17 | Denver Grizzlies | Western League | , | |
| Earl Lowe | lowe--000ear | 1903 | Dul.-Universal | Independent | , | ||
| George Lowell | lowell001geo | 1903 | 5/3-9/23 | Joplin Miners | Missouri Valley League | , | |
| Dennis Lowney | lowney001dan | 1903 | 4/27-9/20 | Nashville Volunteers | Southern Association | , | |
| Robert Loxson | noxon-001--- | 1903 | 5/1-5/28 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Bill Luby | luby--001wil | 1903 | 5/8-9/11 | Hartford Senators | Connecticut League | , | |
| Lucas | lucas-023--- | 1903 | Groton SD | Independent | , | ||
| Lucas | lucas-023--- | 1903 | 7/24-8/3 | Grand Forks Forkers | Northern League | , | |
| Harry Lucas | lucas-000buf | 1903-04 | , | ||||
| Harry Lucas | lucas-000buf | 1903 | Salem | Willamette Valley | Salem, OR | ||
| James Lucas | lucas-001jam | 1903 | Zanesville OH | ProtAssn | , | ||
| William Lucas | lucas-005wil | 1903 | Pres.-Sec.-Trea. | Pacific National League | , | ||
| Fred Luchia | lucia-001fre | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| Con Lucid | lucid-001con | 1903 | 4/25- | Fort Worth Panthers | Texas League | , | |
| Con Lucid | lucid-001con | 1903 | -6/28 | Corsicana Oil Citys | Texas League | , | |
| Con Lucid | lucid-001con | 1903 | 7/7-8/15 | Beaumont Oil Gushers | South Texas League | , | |
| Bernard Ludes | 1903 | Salina-Invincibles | Independent | , | |||
| Francis Ludes | 1903 | Salina-Invincibles | Independent | , | |||
| Bill Ludwig | ludwig002wil | 1903 | 4/26-8/2 | Minneapolis Millers | American Association | , | |
| Herman Luettke | luettk001her | 1903 | Fort Scott Giants | Missouri Valley League | , | ||
| George Lufkin | lufkin001geo | 1903 | , | ||||
| George Lufkin | lufkin001geo | 1903 | 7/2 | Hartford Senators | Connecticut League | , | |
| Baldo Luitich | luitic001bal | 1903 | 5/31-8/27 | Galveston Sand Crabs | South Texas League | , | |
| George Luke | 1903 | +8/9+ | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Harry Lumley | lumley001har | 1903 | 4/28-5/12 | Colorado Springs Millionaires | Western League | , | |
| Harry Lumley | lumley001har | 1903 | 109 g. | Seattle Siwashes | Pacific Coast League | , | |
| Jack Lundbom | lundbo001joh | 1903 | 4/15- | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Jack Lundbom | lundbo001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| Jack Lundbom | lundbo001joh | 1903 | Butte Miners | Pacific National League | , | ||
| Billy Lush | lush--001wil | 1903 | 119 g. | Detroit | American League | Detroit, MI | |
| Johnny Lush | lush--001joh | 1903 | Williamsport PA | Independent | , | ||
| Charlie Luskey | luskey001cha | 1903 | 5/9-9/24 | Buffalo Bisons | Eastern League | , | |
| Lutcher | 1903 | +8/18+ | Williamsport PA | Independent | , | ||
| William Luyster | luyste001wil | 1903 | 7/23-9/25 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Bob Lyman | lyman-001rob | 1903 | 5/8-6/9 | Holyoke Paperweights | Connecticut League | , | |
| Bobby Lynch | lynch-006rob | 1903 | Notre Dame | College | , | ||
| Bobby Lynch | lynch-006rob | 1903 | 6/22-7/18 | Atlanta Crackers | Southern Association | , | |
| Bobby Lynch | lynch-006rob | 1903 | 8/2-9/19 | Memphis Egyptians | Southern Association | , | |
| Ed Lynch | lynch-002edw | 1903 | 4/25-9/19 | Little Rock Travelers | Southern Association | , | |
| Henry Lynch | lynch-003hen | 1903 | 215 g. | San Francisco Seals | Pacific Coast League | , | |
| Joseph Lynch | lynch-001jos | 1903 | 5/20-6/27+ | Winnipeg Maroons | Northern League | , | |
| Joseph Lynch | lynch-001jos | 1903 | +7/17-9/8 | Fargo | Northern League | , | |
| Mike Lynch | lynch-003mic | 1903 | 132 g. | Tacoma Tigers | Pacific National League | , | |
| Mike Lynch | lynch-003mic | 1903 | 8/23 | Olympia Senators | Southwest Washington League | , | |
| Sunny Lynch | lynch-000sun | 1903 | 4 g. | Brewton | Interstate League | , | |
| Sunny Lynch | lynch-000sun | 1903 | Mobile | Interstate League | , | ||
| Christopher Lynskey | lynsky001chr | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Christopher Lynskey | lynsky001chr | 1903 | Huntsville | Tennessee-Alabama League | , | ||
| Lyons | lyons-046--- | 1903 | 6/10-6/17 | Duluth Cardinals | Northern League | , | |
| Charles Lyons | lyons-003cha | 1903 | no g. | Kansas City Cowboys | American Association | , | |
| Charles Lyons | lyons-003cha | 1903 | 5/2-5/30 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Charles Lyons | lyons-001cha | 1903 | 5/22-5/26 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Charles Lyons | lyons-001cha | 1903 | +7/19+ | Kewanna IN | Independent | , | |
| Charles Lyons | lyons-001cha | 1903 | 31 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Charles Lyons | lyons-001cha | 1903 | 5/22-5/26 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Charles Lyons | lyons-001cha | 1903 | 31 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Denny Lyons | lyons-002den | 1903 | 4/25-8/3 | Beaumont Oil Gushers | South Texas League | , | |
| Ed Lyons | 1903 | Little Rock Travelers | Southern Association | , | |||
| Joseph Lyons | lyons-001jos | 1903 | 8/24-9/26 | Baltimore Orioles | Eastern League | , | |
| Walter Lyons | lyons-001wal | 1903 | 110 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | |
| Daniel Lytle | lytle-001dan | 1903 | 5/2-5/26 | Rochester Bronchos | Eastern League | , | |
| Daniel Lytle | lytle-001dan | 1903 | 5/30-8/23 | Albany Senators | New York State League | , | |
| Daniel Lytle | lytle-001dan | 1903 | 8/24-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Charles Maag | maag--001c-- | 1903 | Canton OH | Amateur | , | ||
| Malcolm MacDonald | mcdona001jam | 1903 | Pittsburg Coal Diggers | Missouri Valley League | , | ||
| Harry Mace | mace--002har | 1903 | 5/3-5/27 | Umpire | Southern Association | , | |
| Ed MacGamwell | mcgamw002edw | 1903 | 4/30-5/16 | Buffalo Bisons | Eastern League | , | |
| Ed MacGamwell | mcgamw002edw | 1903 | 6/24-9/20 | Albany Senators | New York State League | , | |
| Frank MacHale | mchale001fra | 1903 | York PA | Independent | , | ||
| Mack | mack--028--- | 1903 | 7/25 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Eugene Mack | mack--001eug | 1903 | 6/24 | Hartford Senators | Connecticut League | , | |
| Eugene? Mack | mack--030--- | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| Reddy Mack | mack--001red | 1903 | Quincy IL | , | |||
| Reddy Mack | mack--001red | 1903 | 6/29-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| William Mack | mack--001wil | 1903 | Youngstown OH | Independent | , | ||
| William Mack | mack--003wil | 1903 | Elmira-FatherMichael | Independent | , | ||
| Ed Mackey | mackey001a-- | 1903 | Umpire | Texas League | , | ||
| John Mackey | mackey004--- | 1903 | Aberdeen WA | Independent | , | ||
| Robert Mackey | mackey001rob | 1903 | 5/11-8/21+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| John Mackin | mackin000jac | 1903 | Dollar Bay MI | Independent | , | ||
| Madden | madden012--- | 1903 | 7/17-7/28 | Hartford Senators | Connecticut League | , | |
| Walter Madden | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |||
| Madenspacher | madens000--- | 1903 | 8/12-8/15 | Binghamton Bingoes | New York State League | , | |
| John Madigan | 1903 | Atlantic | Southwest Iowa League | , | |||
| Patrick Madigan | madiga000smo | 1903 | 6/5-7/5 | Des Moines Undertakers | Western League | , | |
| Art Madison | madiso002art | 1903 | 4/30-5/30 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Art Madison | madiso002art | 1903 | 6/9-9/25 | Rochester Bronchos | Eastern League | , | |
| Bill Magee | magee-001wil | 1903 | 4/30-9/23 | Buffalo Bisons | Eastern League | , | |
| Sherry Magee | magee-001she | 1903 | Allentown PA | Independent | , | ||
| Jake Magie | magie-001jac | 1903 | 5/8-9/20 | Syracuse Stars | New York State League | , | |
| George Magoon | magoon001geo | 1903 | 42 g. | Cincinnati | National League | Cincinnati, OH | |
| George Magoon | magoon001geo | 1903 | 94 g. | Chicago | American League | Chicago, IL | |
| Maguire | maguir012--- | 1903 | 5/8-5/12 | New Haven Blues | Connecticut League | , | |
| Jack Mahaffey | mahaff001joh | 1903 | Springfield Midgets | Missouri Valley League | , | ||
| Lou Mahaffey | mahaff002lou | 1903 | 4/14-5/11 | Umpire | Pacific National League | , | |
| Lou Mahaffey | mahaff002lou | 1903 | Umpire | Pacific Coast League | , | ||
| Lou Mahaffey | mahaff002lou | 1903 | 6/13- | Umpire | Pacific National League | , | |
| Charles Mahan | mahan-002--- | 1903 | 6/5-6/29 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Tom Maher | maher-001tho | 1903 | 4/28-8/3 | St. Joseph Saints | Western League | , | |
| William Mahling | mahlin001wil | 1903 | 4/25- | Little Rock Travelers | Southern Association | , | |
| William Mahling | mahlin001wil | 1903 | -5/22 | Pine Bluff Lumbermen | Cotton States League | , | |
| William Mahling | mahlin001wil | 1903 | 5/23-9/19 | Little Rock Travelers | Southern Association | , | |
| Ed Mahoney | mahone001edw | 1903 | Ogden UT | Independent | , | ||
| Ed Mahoney | mahone001edw | 1903 | +7/9-7/24+ | Helena Senators | Pacific National League | , | |
| Ed Mahoney | mahone001edw | 1903 | 8/- | Vancouver | Independent | , | |
| Willard Mains | mains-001wil | 1903 | 5/11-9/19 | Syracuse Stars | New York State League | , | |
| Edgar Maitland | maitla001edg | 1903 | Williamsport PA | Independent | , | ||
| John Malarkey | malark001joh | 1903 | - 9/20 | 32 g. | Boston | National League | Boston, MA |
| Malay | 1903 | 8/23-8/25 | Joplin Miners | Missouri Valley League | , | ||
| Charlie Malay | malay-001cha | 1903 | 5/8-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Maley | maley-000--- | 1903 | 8/23-8/25 | Joplin Miners | Missouri Valley League | , | |
| Malone | malone044--- | 1903 | 7/16 | Rochester Bronchos | Eastern League | , | |
| Billy Maloney | malone003wil | 1903 | 4/22-7/21 | Kansas City Cowboys | American Association | , | |
| Billy Maloney | malone003wil | 1903 | 8/11-9/21 | Minneapolis Millers | American Association | , | |
| Curley Maloney | malone005jam | 1903 | 4/25-8/25 | Corsicana Oil Citys | Texas League | , | |
| John Maloney | malone002joh | 1903 | Fargo | Northern League | , | ||
| William Maloney | malone005wil | 1903 | 5/1-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| William Maloney | malone005wil | 1903 | 5/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| George Manion | manion001geo | 1903 | Canadian League | , | |||
| George Manion | manion001geo | 1903 | 5/15-5/21 | Binghamton Bingoes | New York State League | , | |
| Eddie Mann | 1903 | Trinity College | College | , | |||
| Harry Manner | manner001har | 1903 | 5/7-9/19 | Montgomery Black Sox | Southern Association | , | |
| Jack? Manning | 1903 | 6/29-9/9 | Addison | Southern Tier | , | ||
| Tommy Manning | mannin001tho | 1903 | 5/9-9/12 | Meriden Silverites | Connecticut League | , | |
| Moxie Manuel | manuel001mar | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Art Marcan | marcan002art | 1903 | 5/5-5/25 | St. Paul Saints | American Association | , | |
| Art Marcan | marcan002art | 1903 | 5/28-6/25 | Toledo Mud Hens | American Association | , | |
| Art Marcan | marcan002art | 1903 | 6/29-9/20 | Indianapolis Indians | American Association | , | |
| March | march-002--- | 1903 | 6/4-6/9 | Haverhill Hustlers | New England League | , | |
| Marion | marion006--- | 1903 | 6/2 | Concord Marines | New England League | , | |
| George Markley | markle001geo | 1903 | 4/30-6/25 | Evansville River Rats | Central League | , | |
| George Markley | markle001geo | 1903 | 7/1-9/15 | Atlanta Crackers | Southern Association | , | |
| John Marnette | 1903 | Ossining/Catskill | Hudson River League | Ossining, | |||
| Maroney | marone009--- | 1903 | 5/9-5/30 | Hartford Senators | Connecticut League | , | |
| Maroney | marone012--- | 1903 | 7/18-7/21 | Schenectady Frog Alleys | New York State League | , | |
| James Maroney | marone001--- | 1903 | 5/12-5/19 | Norwich Reds | Connecticut League | , | |
| James Maroney | marone001--- | 1903 | 6/3-6/17 | Nashua | New England League | , | |
| James Maroney | marone001--- | 1903 | 7/16 | Meriden Silverites | Connecticut League | , | |
| George Marquis | 1903 | Whitman College | College | , | |||
| George Marquis | 1903 | +5/15-5/30+ | Pendleton | Inland Empire League | , | ||
| Archie Marshall | marsha001arc | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Doc Marshall | marsha005wil | 1903 | 4/28-9/17 | Des Moines Undertakers | Western League | , | |
| George Marshall | 1903 | Ogden UT | Independent | , | |||
| Joe Marshall | marsha001jos | 1903 | San Francisco Pirates | Pacific National League | , | ||
| Joe Marshall | marsha001jos | 1903 | 9/7- | 10 g. | Pittsburgh | National League | Pittsburgh, PA |
| Otis Marshall | marsha001oti | 1903 | 5/22-6/29 | Springfield Midgets | Missouri Valley League | , | |
| Doc Martell | martel001leo | 1903 | Weymouth MA | High School | , | ||
| Doc Martell | martel001leo | 1903-04 | Georgetown | College | , | ||
| Martin | martin121--- | 1903 | 5/8 | Binghamton Bingoes | New York State League | , | |
| Martin | martin124--- | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Martin | martin021--- | 1903 | 7/12-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Carmel Martin | martin002car | 1903 | San Jose | California State League | , | ||
| Clint Martin | martin002cli | 1903 | 68 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Clint Martin | martin002cli | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| Dave Martin | martin001dav | 1903 | 4/27-5/3 | Kansas City Cowboys | American Association | , | |
| Dave Martin | martin001dav | 1903 | 5/20-9/8 | Crookston Crooks | Northern League | , | |
| Frank Martin | martin001fra | 1903 | 4/22-5/2 | Louisville Colonels | American Association | , | |
| Frank Martin | martin001fra | 1903 | 5/6-9/21 | Minneapolis Millers | American Association | , | |
| Harry Martin | martin007har | 1903 | GraR-Independents | Independent | , | ||
| J. Martin | 1903 | Kingston Colonials | Hudson River League | , | |||
| James Martin | martin030jam | 1903 | 14 g. | Mobile | Interstate League | , | |
| James Martin | martin030jam | 1903 | Brewton | Interstate League | , | ||
| Joe Martin | martin006jos | 1903 | 4/28- | 35 g. | Washington | American League | Washington, DC |
| Joe Martin | martin006jos | 1903 | -8/31 | 44 g. | St. Louis | American League | St. Louis, MO |
| Felix Martinke | martin003fel | 1903 | 20 g. | Oakland Oaks | Pacific Coast League | , | |
| Miles Maryott | maryot001mil | 1903 | 6/8-7/24 | Holdredge | Central Nebraska League | , | |
| Del Mason | mason-001ade | 1903 | 5/2-5/9 | Toronto Maple Leafs | Eastern League | , | |
| Del Mason | mason-001ade | 1903 | 5/22-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Harry Mason | mason-002har | 1903 | Buffalo Univ. | College | , | ||
| Harry Mason | mason-002har | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Nel Mason | mason-001nel | 1903 | 5/12-6/23 | Fort Wayne Railroaders | Central League | , | |
| Nel Mason | mason-001nel | 1903 | +7/26+ | Paulding OH | Independent | , | |
| Bill Massey | massey001bil | 1903 | 4/30-9/26 | Toronto Maple Leafs | Eastern League | , | |
| John Massing | massin001joh | 1903 | preseason | Indianapolis Indians | American Association | , | |
| Christy Mathewson | mathew001chr | 1903 | 45 g. | New York | National League | New York, NY | |
| Stanislaus Mathieu | mathie000sta | 1903 | 5/14-5/20 | Norwich Reds | Connecticut League | , | |
| Jimmy Mathison | mathis002jam | 1903 | 4/25-7/18 | Memphis Egyptians | Southern Association | , | |
| Jimmy Mathison | mathis002jam | 1903 | 7/22-9/19 | Little Rock Travelers | Southern Association | , | |
| Al Mattern | matter001alo | 1903 | +9/16+ | Caledonia NY | Independent | , | |
| Matthews | matthe055--- | 1903 | 5/2 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Harry Matthews | matthe001har | 1903 | 4/27-9/20 | Atlanta Crackers | Southern Association | , | |
| Samuel Matthews | matthe000tob | 1903 | Ossining/Catskill | Hudson River League | Catskill, | ||
| Thomas Matthews | matthe001tho | 1903 | St. Albans College | College | , | ||
| Thomas Matthews | matthe001tho | 1903 | +8/27+ | 5 g. | Decatur | Tennessee-Alabama League | , |
| Thomas Matthews | matthe001tho | 1903 | St. Albans | College | , | ||
| Thomas Matthews | matthe001tho | 1903 | 6/12-6/24 | Anniston Invincibles | Alabama-Georgia League | , | |
| Thomas Matthews | matthe001tho | 1903 | +8/17+ | Gadsden AL | Independent | , | |
| Thomas Matthews | matthe001tho | 1903 | 8/23-9/3 | Decatur | Tennessee-Alabama League | , | |
| Tommy Matthews | matthe002tom | 1903 | 3 g. | Montgomery Black Sox | Interstate League | , | |
| Walter Matthews | matthe000tob | 1903 | Ossining/Catskill | Hudson River League | Catskill, | ||
| Wilson Matthews | matthe004wil | 1903 | 6/11-7/17 | Umpire | South Texas League | , | |
| Wilson Matthews | matthe004wil | 1903 | 7/18-7/27 | Beaumont Oil Gushers | South Texas League | , | |
| Wilson Matthews | matthe004wil | 1903 | 8/4-8/30 | Umpire | South Texas League | , | |
| Al Mauch | mauch-001alb | 1903 | Little Rock Travelers | Southern Association | , | ||
| Patrick Mauch | mauch-001pat | 1903 | Pt. Washington | Independent | , | ||
| Hal Mauck | mauck-001hal | 1903 | 5/4-5/19 | Umpire | Central League | , | |
| Hal Mauck | mauck-001hal | 1903 | Princeton IN | Independent | , | ||
| Harry Maupin | maupin001har | 1903 | 4/19-5/29+ | Tacoma Tigers | Pacific National League | , | |
| Harry Maupin | maupin001har | 1903 | 6/9-10/4 | Seattle Chinooks | Pacific National League | , | |
| John Maury | maury-003--- | 1903 | Allentown | Independent | , | ||
| Maxwell | 1903 | 4/30- | Dayton | Inland Empire League | , | ||
| Elwood Maxwell | maxwel001c-- | 1903 | York PA | Independent | , | ||
| Ira Maxwell | 1903 | Montgomery Black Sox | Southern Association | , | |||
| William May | may---002wil | 1903 | Selma YMCA | Alabama-Georgia League | , | ||
| Bert McAfee | mcafee002ber | 1903 | +9/12+ | Sprii-Garnett | Independent | , | |
| Dan McAleese | mcalee001dan | 1903 | +7/13+ | Sharon PA | Independent | , | |
| Dan McAleese | mcalee001dan | 1903 | Salamanca | , | |||
| Dan McAleese | mcalee001dan | 1903 | 9/5- | Sharon PA | Independent | , | |
| Jack McAleese | mcalee001joh | 1903 | 5/2-5/31 | Rochester Bronchos | Eastern League | , | |
| Jack McAleese | mcalee001joh | 1903 | 6/18-9/12 | Baltimore Orioles | Eastern League | , | |
| Sport McAllister | mcalli001lew | 1903 | Detroit | American League | Detroit, MI | ||
| Sport McAllister | mcalli001lew | 1903 | 9/11-9/23 | Buffalo Bisons | Eastern League | , | |
| Tom McAndrew | mcandr002tho | 1903 | 4/22-8/12 | Kansas City Cowboys | American Association | , | |
| Tom McAndrew | mcandr002tho | 1903 | 8/21-9/20 | Birmingham Barons | Southern Association | , | |
| Mike McAndrews | mcandr001mic | 1903 | 5/8-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Gene McAuliffe | mcauli002eug | 1903 | 7/23-8/26 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| McBride | mcbrid017--- | 1903 | 8/13-8/23+ | Pulaski | Tennessee-Alabama League | , | |
| Algie McBride | mcbrid001alg | 1903 | , | ||||
| George McBride | mcbrid001geo | 1903 | 4/28-5/6 | Peoria Distillers | Western League | , | |
| George McBride | mcbrid001geo | 1903 | 5/9-9/17 | St. Joseph Saints | Western League | , | |
| John McBurney | mcburn000joh | 1903 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | ||
| Bill McCabe | mccabe005wil | 1903 | 5/23-9/27 | Poughkeepsie Colts | Hudson River League | , | |
| Francis McCabe | mccabe002fra | 1903 | Dartmouth Col | College | , | ||
| Francis McCabe | mccabe002fra | 1903 | Fabyans NH | Independent | , | ||
| William McCabe | mccabe008wil | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| William McCabe | mccabe001wil | 1903 | Shamokin PA | Independent | , | ||
| Charles McCafferty | mccaff002cha | 1903 | 5/22-6/19+ | Grand Forks Forkers | Northern League | , | |
| Charles McCafferty | mccaff002cha | 1903 | +7/11+ | 15 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, |
| Charles McCafferty | mccaff002cha | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| Jerry McCall | mccall001jer | 1903 | Grand Rapids MI | Independent | , | ||
| Jack McCallister | mccall001jac | 1903 | Kane PA | Independent | , | ||
| McCann | mccann014--- | 1903 | 5/14-5/20 | Albany Senators | New York State League | , | |
| Gene McCann | mccann001hen | 1903 | 4/30-9/24 | Jersey City Skeeters | Eastern League | , | |
| Mike McCann | mccann001mic | 1903 | 4/25-9/19 | Little Rock Travelers | Southern Association | , | |
| William McCann | mccann000bil | 1903 | 5/9-5/29 | Utica Pent-Ups | New York State League | , | |
| James McCarten | mccart001jam | 1903 | 5/13-7/5 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| James McCarten | mccart001jam | 1903 | +8/17+ | Burlington | Northern New York League | , | |
| Daniel McCarter | mccart006dan | 1903 | 6/10-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Daniel McCarter | mccart006dan | 1903 | +7/30+ | Canton SD | Independent | , | |
| Arch McCarthy | mccart001arc | 1903 | 5/1-9/12 | Concord Marines | New England League | , | |
| Charles McCarthy | mccart012--- | 1903 | Grand Forks Forkers | Northern League | , | ||
| Dennis McCarthy | mccart001den | 1903 | Seattle Siwashes | Pacific Coast League | , | ||
| Dennis McCarthy | mccart001den | 1903 | 4/14-6/1 | Tacoma Tigers | Pacific National League | , | |
| Dennis McCarthy | mccart001den | 1903 | Boise ID | Independent | , | ||
| Dennis McCarthy | mccart001den | 1903 | 7/23 | Oakland Oaks | Pacific Coast League | , | |
| Dennis McCarthy | mccart001den | 1903 | 7/26-8/6 | Seattle Chinooks | Pacific National League | , | |
| Dennis McCarthy | mccart001den | 1903 | 8/11 | Seattle Siwashes | Pacific Coast League | , | |
| Dennis McCarthy | mccart001den | 1903 | 8/14 | Helena Senators | Pacific National League | , | |
| Jack McCarthy | mccart003joh | 1903 | 108 g. | Cleveland | American League | Cleveland, OH | |
| Jack McCarthy | mccart003joh | 1903 | 24 g. | Chicago | National League | Chicago, IL | |
| Jack McCarthy | mccart004jac | 1903 | 4/30-9/17 | Umpire | Western League | , | |
| Joe McCarthy | mccart004jos | 1903 | San Francisco | California State League | , | ||
| Joe McCarthy | mccart004jos | 1903 | 4/14- | 89 g. | Tacoma Tigers | Pacific National League | , |
| Joe McCarthy | mccart004jos | 1903 | +5/10+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Joe McCarthy | mccart004jos | 1903 | +6/11-8/20 | San Francisco Pirates | Pacific National League | , | |
| Joe McCarthy | mccart004jos | 1903 | -10/4 | Spokane Indians | Pacific National League | , | |
| Joe McCarthy | mccart004jos | 1903 | 17 g. | Seattle Siwashes | Pacific Coast League | , | |
| T. McCarthy | mccart001t-- | 1903 | 5/16-9/12 | Hartford Senators | Connecticut League | , | |
| Timothy McCarthy | mccart001tim | 1903 | 8/8 | Lowell Tigers | New England League | , | |
| Tom McCarthy | mccart005tom | 1903 | 9/1-9/7 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Joe McCarty | 1903 | Williams College | College | , | |||
| Joe McCarty | 1903 | Corning NY | Independent | , | |||
| Albert McCauley | mccaul007--- | 1903 | Columbia | Tennessee-Alabama League | , | ||
| Albert McCauley | mccaul007--- | 1903 | Decatur | Tennessee-Alabama League | , | ||
| Pat McCauley | mccaul001pat | 1903 | 4/30-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Pat McCauley | mccaul001pat | 1903 | 7/20-8/2 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Pat McCauley | mccaul001pat | 1903 | New York | American League | New York, NY | ||
| T. B. McCauley | mccaul007--- | 1903 | +5/14-6/19+ | Decatur AL | Independent | , | |
| T. B. McCauley | mccaul007--- | 1903 | Huntsville AL | Independent | , | ||
| T. B. McCauley | mccaul007--- | 1903 | +9/1+ | Decatur | Tennessee-Alabama League | , | |
| Billy McCausland | mccaus001wil | 1903 | 5/31-6/4 | Denver Grizzlies | Western League | , | |
| Bernard McCay | mccay-001ber | 1903 | no g. | Spokane Indians | Pacific National League | , | |
| Bernard McCay | mccay-001ber | 1903 | no g. | Tacoma Tigers | Pacific National League | , | |
| Bernard McCay | mccay-001ber | 1903 | 4/23-8/15+ | Seattle Chinooks | Pacific National League | , | |
| Walter McClelland | 1903 | Pawt-YMS | InterCity | , | |||
| Howard McClintock | mcclin001wil | 1903 | 4/27-5/9 | Beaumont Oil Gushers | South Texas League | , | |
| Howard McClintock | mcclin001wil | 1903 | 5/19-6/24 | Houston Buffaloes | South Texas League | , | |
| Charles McCloskey | mcclos002cha | 1903 | 6/27-7/4 | Denver Grizzlies | Western League | , | |
| Charles McCloskey | 1903 | 6/30-7/8 | Providence Grays | Eastern League | , | ||
| John McCloskey | mcclos001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | ||
| John McCloskey | mcclos001joh | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| John McCloskey | mcclos001joh | 1903 | San Francisco Pirates | Pacific National League | , | ||
| McCloud | mcclou004--- | 1903 | 9/12 | Decatur | Tennessee-Alabama League | , | |
| Harry McCloud | mcclou002har | 1903 | 5/5,5/18 | Manchester | New England League | , | |
| Harry McCloud | mcclou002har | 1903 | 6/3-7/25;8/15-9/11 | Umpire | New England League | , | |
| William McCombs | mccomb001wil | 1903 | 6/2 | Wheeling Stogies | Central League | , | |
| William McCombs | mccomb001wil | 1903 | 8/7-9/16 | Wheeling Stogies | Central League | , | |
| McConnell | 1903 | 5/26-5/27 | Fargo | Northern League | , | ||
| Amby McConnell | mcconn001amb | 1903 | Beloit College | College | , | ||
| George McConnell | mcconn001geo | 1903 | 5/6-9/16 | Dayton Veterans | Central League | , | |
| Jack McConnell | mcconn002joh | 1903 | 4/30-9/17 | St. Joseph Saints | Western League | , | |
| Lanty McConnell | mcconn002lan | 1903 | 5/22- | Leavenworth White Sox | Missouri Valley League | , | |
| McCool | 1903 | 5/25 | St. Joseph Saints | Western League | , | ||
| John McCord | mccord001joh | 1903 | 4/27-9/17 | Louisville Colonels | American Association | , | |
| Charles McCormack | 1903 | Kingston Colonials | Hudson River League | , | |||
| Mike McCormack | mccorm003mic | 1903 | 5/8-9/12 | Holyoke Paperweights | Connecticut League | , | |
| McCormick | mccorm029--- | 1903 | 9/12 | New London Whalers | Connecticut League | , | |
| Barry McCormick | mccorm002wil | 1903 | 61 g. | St. Louis | American League | St. Louis, MO | |
| Barry McCormick | mccorm002wil | 1903 | 63 g. | Washington | American League | Washington, DC | |
| Harry McCormick | mccorm004har | 1903 | 4/30-9/26 | Jersey City Skeeters | Eastern League | , | |
| Jim McCormick | mccorm002jim | 1903 | no g. | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Jim McCormick | mccorm002jim | 1903 | 5/8-9/20 | Ilion Typewriters | New York State League | , | |
| John McCrane | mccran001joh | 1903 | Coatesville PA | Independent | , | ||
| Judge McCredie | mccred001wal | 1903 | 7/3-9/26 | Baltimore Orioles | Eastern League | , | |
| Judge McCredie | mccred001wal | 1903 | 4/17- | Brooklyn | National League | Brooklyn, NY | |
| Tom McCreery | mccree001tho | 1903 | 4/22-7/10 | Minneapolis Millers | American Association | , | |
| Tom McCreery | mccree001tho | 1903 | 40 g. | Brooklyn | National League | Brooklyn, NY | |
| Tom McCreery | mccree001tho | 1903 | -9/27 | 20 g. | Boston | National League | Boston, MA |
| Charles McCullough | mccull001cha | 1903 | 5/8-9/10 | Bridgeport Orators | Connecticut League | , | |
| Hugh McCullum | mccull003hug | 1903 | +6/21+ | Dallas-Santa Fe | Independent | , | |
| Hugh McCune | 1903 | Tren.-YMCA | Independent | , | |||
| McCusker | 1903 | 8/14 | Brockton/New Bedford Whalers | New England League | New Bedford, | ||
| Sandy McDermott | mcderm001san | 1903 | 5/1-5/27 | Umpire | Southern Association | , | |
| Tom McDermott | mcderm005tho | 1903 | 5/1-9/12 | Fall River Indians | New England League | , | |
| Will McDevitt | mcdevi001wil | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Will McDevitt | mcdevi001wil | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Eddie McDill | mcdill001edw | 1903 | 5/2-6/19 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Eddie McDill | mcdill001edw | 1903 | 6/23-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Angus McDonald | 1903 | Hous.-Cawthons | Amateur | , | |||
| Angus McDonald | 1903 | 5/3-7/4 | Houston Buffaloes | South Texas League | , | ||
| Charles McDonald | mcdona004cha | 1903 | 4/24-6/27 | Kansas City Cowboys | American Association | , | |
| Charles McDonald | mcdona004cha | 1903 | 7/14-9/20 | Minneapolis Millers | American Association | , | |
| D. McDonald | mcdona004cha | 1903 | 4/28-5/22 | Kansas City Cowboys | American Association | , | |
| E. L. McDonald | mcdona000el- | 1903 | Inland Empire League | , | |||
| Ed McDonald | 1903 | +5/21-6/4+ | Hous.-Cawthons | Amateur | , | ||
| Ed McDonald | 1903 | 4/25-6/21 | Houston Buffaloes | South Texas League | , | ||
| Edward McDonald | mcdona002edw | 1903 | Hudson Marines | Hudson River League | , | ||
| Jim McDonald | mcdona005ray | 1903 | 6/4-7/22 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Joseph McDonald | mcdona003jos | 1903 | Lebanon PA | Independent | , | ||
| Patrick McDonald | 1903 | Plattsburg NY | Independent | , | |||
| Ray McDonald | mcdona004cha | 1903 | 4/28-5/22 | Kansas City Cowboys | American Association | , | |
| Ray McDonald | mcdona005ray | 1903 | 41 g. | Pittsburg Coal Diggers | Missouri Valley League | , | |
| McDonnell | mcdona057--- | 1903 | 7/6-7/27 | Hartford Senators | Connecticut League | , | |
| McDonough | 1903 | +6/4+ | Pendleton | Inland Empire League | , | ||
| Sandy McDougal | mcdoug002joh | 1903 | 5/8-6/5 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Sandy McDougal | mcdoug002joh | 1903 | 6/22-9/18 | Schenectady Frog Alleys | New York State League | , | |
| James McDowell | mcdowe002jam | 1903 | StL-Kirkwood AC | Independent | , | ||
| Pryor McElveen | mcelve001pry | 1903 | Huntsville | Tennessee-Alabama League | , | ||
| Thomas McEnaney | 1903 | 5/11-5/28 | Lawrence Colts | New England League | , | ||
| John McEvoy | 1903 | +9/19+ | Rich.-Swansboro | Independent | , | ||
| Fred McFall | mcfall001fre | 1903 | 5/3-6/3 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Fred McFall | mcfall001fre | 1903 | 6/11-6/21 | Rochester Bronchos | Eastern League | , | |
| John McFall | 1903 | Charleston Col | College | , | |||
| Claude McFarlan | mcfarl002cla | 1903 | 5/16-6/28 | New Orleans Pelicans | Southern Association | , | |
| Claude McFarlan | mcfarl002cla | 1903 | 7/6-7/11 | Memphis Egyptians | Southern Association | , | |
| Claude McFarlan | mcfarl002cla | 1903 | 7/12-9/14 | Shreveport Giants | Southern Association | , | |
| Dan McFarlan | mcfarl002dan | 1903 | 5/4-6/21 | Rochester Bronchos | Eastern League | , | |
| Dan McFarlan | mcfarl002dan | 1903 | 7/14-7/20 | Providence Grays | Eastern League | , | |
| Dan McFarlan | mcfarl002dan | 1903 | 32 g. | Portland Browns | Pacific Coast League | , | |
| Chappie McFarland | mcfarl002cha | 1903 | 28 g. | St. Louis | National League | St. Louis, MO | |
| Herm McFarland | mcfarl001her | 1903 | 103 g. | New York | American League | New York, NY | |
| Monte McFarland | mcfarl001mon | 1903 | 115 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Roy McFarland | mcfarl001roy | 1903 | 1 g. | Sacramento Senators | Pacific Coast League | , | |
| Roy McFarland | mcfarl001roy | 1903 | Albany | Willamette Valley | Albany, OR | ||
| John McFarlin | mcfarl001j-- | 1903 | Jacksonv. State | College | , | ||
| John McFarlin | mcfarl001j-- | 1903 | 6/27-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| McFarren | 1903 | 5/24- | Colfax | Inland Empire League | , | ||
| Jack McFetridge | mcfetr001joh | 1903 | -9/27 | 14 g. | Philadelphia | National League | Philadelphia, PA |
| Tommy McGaughean | 1903 | Saugerties | Hudson River League | , | |||
| Carl McGaughey | 1903 | Butler College | College | , | |||
| Carl McGaughey | 1903 | 4/25-5/22 | Kansas City Cowboys | American Association | , | ||
| Carl McGaughey | 1903 | 6/29-7/1+ | Duluth Cardinals | Northern League | , | ||
| Carl McGaughey | 1903 | +7/12-7/31+ | Superior Longshoremen | Northern League | , | ||
| William McGeary | mcgear001wil | 1903 | 5/11-5/15 | Schenectady Frog Alleys | New York State League | , | |
| Connie McGeehan | mcgeeh001cor | 1903 | 7/15-8/14 | Philadelphia | American League | Philadelphia, PA | |
| Charles McGill | mcgill002cha | 1903 | 20 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| William McGill | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Willie McGill | mcgill005wil | 1903 | 4/23-7/12 | Milwaukee Brewers | American Association | , | |
| Willie McGill | mcgill005wil | 1903 | 8/7-8/26 | Toledo Mud Hens | American Association | , | |
| Hugh McGilligan | mcgill001hug | 1903 | 6 g. | Oakland Oaks | Pacific Coast League | , | |
| Hugh McGilligan | mcgill001hug | 1903 | +4/25-7/19+ | Butte Miners | Pacific National League | , | |
| Hugh McGilligan | mcgill001hug | 1903 | +8/2-8/4+ | Seattle Chinooks | Pacific National League | , | |
| Hugh McGilligan | mcgill001hug | 1903 | Spokane Indians | Pacific National League | , | ||
| Hugh McGilligan | mcgill001hug | 1903 | 45 g. | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Bill McGilvray | mcgilv001wil | 1903 | 6/27-7/8 | Denver Grizzlies | Western League | , | |
| Bill McGilvray | mcgilv001wil | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| Bill McGilvray | mcgilv001wil | 1903 | 8/19-9/17 | Denver Grizzlies | Western League | , | |
| A. McGinley | mcginl000a-- | 1903 | 5/2-5/9+ | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Jim McGinley | mcginl001jam | 1903 | 5/1-9/12 | Haverhill Hustlers | New England League | , | |
| Frank McGinnis | 1903 | Seattle Chinooks | Pacific National League | , | |||
| Stoney McGlynn | mcglyn001uly | 1903 | Harrisburg PA | Independent | , | ||
| Stoney McGlynn | mcglyn001uly | 1903 | New London Whalers | Connecticut League | , | ||
| E. McGoughnea | mcgoug000tom | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| Benny McGrady | mcgrad002--- | 1903 | Rochester | Catholic | , | ||
| McGrath | 1903 | Dartmouth | College | , | |||
| McGrath | 1903 | Claremont NH | Independent | , | |||
| Bernard McGraw | mcgraw009--- | 1903 | 6/30-7/2 | Concord Marines | New England League | , | |
| John McGraw | mcgraw003joh | 1903 | New York | National League | New York, NY | ||
| John McGraw | mcgraw005joh | 1903 | 5/8-5/26 | New London Whalers | Connecticut League | , | |
| Eugene McGreevy | mcgree001eug | 1903 | 44 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Clyde McGregor | mcgraw009--- | 1903 | Wash. & Jefferson | College | , | ||
| Clyde McGregor | mcgraw009--- | 1903 | 7/4 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Ted McGrew | mcgrew001har | 1903 | 4/30-9/16 | Marion Oilworkers | Central League | , | |
| Eddie McGucken | mcguck002--- | 1903 | 4/30-6/7 | Walla Walla | Inland Empire League | , | |
| Eddie McGucken | mcguck002--- | 1903 | +6/14 | Dayton | Inland Empire League | , | |
| Eddie McGucken | mcguck002--- | 1903 | Walla Walla WA | Independent | , | ||
| McGuire | mcguir031--- | 1903 | 5/17-5/18 | Terre Haute Hottentots | Central League | , | |
| McGuire | 1903 | 5/21-5/22 | Albany Senators | New York State League | , | ||
| Deacon McGuire | mcguir006jam | 1903 | Detroit | American League | Detroit, MI | ||
| Jim McGuire | mcguir001jam | 1903 | 4/27-9/20 | Birmingham Barons | Southern Association | , | |
| William McGuire | mcguir002wil | 1903 | 5/20-6/27+ | Fargo | Northern League | , | |
| William McGuire | mcguir002wil | 1903 | 8/20-8/30+ | Superior Longshoremen | Northern League | , | |
| Thomas McGuirk | mcguir004tho | 1903 | Saugerties | Hudson River League | , | ||
| Bob McHale | mchale001bob | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Jim McHale | mchale001jam | 1903 | 4/14-10/4 | Butte Miners | Pacific National League | , | |
| Harry McIntire | mcinti001joh | 1903 | 4/25-9/20 | Memphis Egyptians | Southern Association | , | |
| Butch McIntyre | mcinty001cha | 1903 | 4/22-9/20 | Minneapolis Millers | American Association | , | |
| Matty McIntyre | mcinty001mat | 1903 | 4/30-9/26 | Buffalo Bisons | Eastern League | , | |
| Bernard McKay | mccay-001ber | 1903 | Oakland Oaks | Pacific Coast League | , | ||
| Bernard McKay | mccay-001ber | 1903 | Seattle Chinooks | Pacific National League | , | ||
| Reeve McKay | mckay-001ree | 1903 | 4/27-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Reeve McKay | mckay-001ree | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Arthur McKee | mckee-001art | 1903 | 5/14-9/23 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Benny McKee | 1903 | 6/17- | Youngstown OH | Independent | , | ||
| McKeen | mckeen003--- | 1903 | 5/4 | Leavenworth White Sox | Missouri Valley League | , | |
| Charles McKenna | mckenn001cha | 1903 | 5/1-8/14 | Lowell Tigers | New England League | , | |
| James McKenna | mckenn001jam | 1903 | Lisbon | Independent | , | ||
| James McKenna | mckenn001jam | 1903 | 7/17 | Grand Forks Forkers | Northern League | , | |
| James McKenna | mckenn001jam | 1903 | St. Cloud MN | Independent | , | ||
| John McKenzie | mckenz001joh | 1903 | 5/21-8/16+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Ed McKernan | mckern001edw | 1903 | Sydney OH | Independent | , | ||
| Ed McKernan | mckern001edw | 1903 | 7/11-7/12 | Little Rock Travelers | Southern Association | , | |
| James McKevitt | mckevi001jam | 1903 | 4/14-10/4 | Butte Miners | Pacific National League | , | |
| Byron McKibben | mckibb001byr | 1903 | +5/17-8/16 | Tacoma Tigers | Pacific National League | , | |
| Byron McKibben | mckibb001byr | 1903 | Aberdeen Pippins | Southwest Washington League | , | ||
| Thomas McKinley | mckinl001tho | 1903 | 4/30-9/ | 11 g. | Evansville River Rats | Central League | , |
| McLaughlin | mclaug027--- | 1903 | 9/14-9/26 | Providence Grays | Eastern League | , | |
| McLaughlin | 1903 | Umpire | Northern League | , | |||
| Barney McLaughlin | mclaug003ber | 1903 | 5/1-9/12 | Lowell Tigers | New England League | , | |
| George McLaughlin | mclaug003geo | 1903 | 210 g. | Sacramento Senators | Pacific Coast League | , | |
| Michael McLaughlin | 1903 | Umpire | Michigan State League | , | |||
| Michael McLaughlin | 1903 | 6/29-9/8 | Umpire | Northern League | , | ||
| Michael McLaughlin | 1903 | Umpire | Cotton States League | , | |||
| Warren McLaughlin | mclaug001war | 1903 | - 5/21 | 3 g. | Philadelphia | National League | Philadelphia, PA |
| Warren McLaughlin | mclaug001war | 1903 | 6/18 | Newark Sailors | Eastern League | , | |
| Warren McLaughlin | mclaug001war | 1903 | 6/29-9/12 | New London Whalers | Connecticut League | , | |
| Ralph McLaurin | mclaur001ral | 1903 | Columbia SC | Independent | , | ||
| McLean | 1903 | no g. | Milwaukee Creams | Western League | , | ||
| McLean | 1903 | 8/1-8/5 | Colorado Springs Millionaires | Western League | , | ||
| McLean | mclean013--- | 1903 | 7/20-8/1 | Hartford Senators | Connecticut League | , | |
| Larry McLean | mclean001joh | 1903 | 1 g. | Chicago | National League | Chicago, IL | |
| Larry McLean | mclean001joh | 1903 | 6/13-9/11 | Nashua | New England League | , | |
| Sam McLean | mclean001fra | 1903 | 5/7-9/12 | Norwich Reds | Connecticut League | , | |
| Harry McLear | mclear001har | 1903 | 5/2-5/22 | Leavenworth White Sox | Missouri Valley League | , | |
| Harry McLear | mclear001har | 1903 | 5/24-9/6 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Harry McLear | mclear001har | 1903 | 9/9-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| McLeavy | mcleav000--- | 1903 | Rich.-Eagles | , | |||
| Dan McMahon | mcmaho002dan | 1903 | Jersey City Skeeters | Eastern League | , | ||
| Dan McMahon | mcmaho002dan | 1903 | 5/20-5/28 | Winnipeg Maroons | Northern League | , | |
| Sadie McMahon | mcmaho003joh | 1903 | 8/15 | Baltimore Orioles | Eastern League | , | |
| John McMakin | mcmaki001joh | 1903 | 4/22-9/20 | Columbus Senators | American Association | , | |
| McManus | 1903 | 5/1- | Nashua | New England League | , | ||
| McManus | 1903 | -6/6 | Lawrence Colts | New England League | , | ||
| Frank McManus | mcmanu001fra | 1903 | 4/30-9/26 | Jersey City Skeeters | Eastern League | , | |
| Frank McManus | mcmanu001fra | 1903 | 2 g. | Brooklyn | National League | Brooklyn, NY | |
| Hugh McMurray | mcmurr002hug | 1903 | 4/25-8/26 | Fort Worth Panthers | Texas League | , | |
| Hugh McMurray | mcmurr002hug | 1903 | Stockton | California State League | , | ||
| Bill McNamara | mcnama001wil | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Thomas McNamara | 1903 | +7/11+ | Umpire | New York State League | , | ||
| Thomas McNamara | 1903 | Umpire | Illinois-Indiana-Iowa League | , | |||
| Thomas McNamara | 1903 | 8/5-9/4 | Umpire | Central League | , | ||
| Harry McNeal | mcneal001joh | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Joshua McNeal | mcneal000jos | 1903 | 7/27 | Evansville River Rats | Central League | , | |
| Joshua McNeal | mcneal000jos | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Joshua McNeal | mcneal000jos | 1903 | 8/10-8/28 | Marion Oilworkers | Central League | , | |
| Leon McNeal | mcneal001ski | 1903 | 5/10-9/5 | Aberdeen Pippins | Southwest Washington League | , | |
| Hugh McNeeley | mcneel001har | 1903 | 4/28-9/17 | Colorado Springs Millionaires | Western League | , | |
| Hugh McNeeley | mcneel001har | 1903 | 9/24-10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Bernard McNeil | mcneil001ber | 1903 | 5/6-6/9 | Rochester Bronchos | Eastern League | , | |
| Bernard McNeil | mcneil001ber | 1903 | Addison NY | Independent | , | ||
| James McNeil | mcneil004jam | 1903 | 10 g. | Sharon PA | Independent | , | |
| Will McNeil | mcneil003wil | 1903 | 8/4 | Crookston Crooks | Northern League | , | |
| Brick McNeill | 1903 | 6/- | Colfax | Inland Empire League | , | ||
| Ed McNichol | mcnich001edw | 1903 | 8/25 | Wheeling Stogies | Central League | , | |
| Frank McNichols | mcnich001fra | 1903 | 4/18-5/3+ | Seattle Chinooks | Pacific National League | , | |
| Frank McNichols | mcnich001fra | 1903 | 5/5-5/11+ | Helena Senators | Pacific National League | , | |
| Frank McNichols | mcnich001fra | 1903 | +5/20-9/17+ | Seattle Chinooks | Pacific National League | , | |
| Clyde McNutt | mcnutt001cly | 1903 | no g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Frank McPartlin | mcpart002fra | 1903 | 4/27-5/9 | Columbus Senators | American Association | , | |
| Frank McPartlin | mcpart002fra | 1903 | 5/16-7/9 | Indianapolis Indians | American Association | , | |
| Frank McPartlin | mcpart002fra | 1903 | 7/21 | Rochester Bronchos | Eastern League | , | |
| Frank McPartlin | mcpart002fra | 1903 | 8/8-9/22 | Providence Grays | Eastern League | , | |
| McPherson | mcpher006--- | 1903 | 5/8 | New Haven Blues | Connecticut League | , | |
| John McPherson | mcpher002joh | 1903 | 4/30-9/17 | Milwaukee Creams | Western League | , | |
| McQuaid | mcquai004--- | 1903 | 6/22 | New London Whalers | Connecticut League | , | |
| James McQuaid | mcquai001jam | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| McShane | 1903 | 4/30-5/1 | St. Joseph Saints | Western League | , | ||
| McShane | mcshan001--- | 1903 | +6/6-6/28+ | Piqua OH | Independent | , | |
| McShane | mcshan001--- | 1903 | Urbana | Independent | , | ||
| McShane | mcshan001--- | 1903 | Wapakoneta OH | Independent | , | ||
| McShane | mcshan001--- | 1903 | 7/25-8/11 | Dayton Veterans | Central League | , | |
| James McSorley | mcsorl001jam | 1903 | 5/9-9/19 | Binghamton Bingoes | New York State League | , | |
| Daniel McSurdy | mcsurd001dan | 1903 | Allentown PA | Independent | , | ||
| Ira McTeer | mcteer002--- | 1903 | 4/30-5/12 | Wheeling Stogies | Central League | , | |
| Mattie McVicker | mcvick001mat | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| McWright | mcwrig001--- | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Mead | mead--003--- | 1903 | 4/5 | Seattle Chinooks | Pacific National League | , | |
| Mead | mead--003--- | 1903 | +5/22+ | Dayton | Inland Empire League | , | |
| Mead | mead--003--- | 1903 | 6/14-6/22 | Aberdeen Pippins | Southwest Washington League | , | |
| Edward Meade | meade-000pec | 1903 | 5/21-7/1+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Edward Meade | meade-000pec | 1903 | +7/25-8/16+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Meadows | meadow005--- | 1903 | 7/17 | Corsicana Oil Citys | Texas League | , | |
| Joseph Meagher | meaghe001jos | 1903 | 5/7-5/8 | Fall River Indians | New England League | , | |
| Joseph Meagher | meaghe001jos | 1903 | Burlington | Northern New York League | , | ||
| Pat Meaney | meaney002pat | 1903 | 219 g. | San Francisco Seals | Pacific Coast League | , | |
| Leonard Medlenka | 1903 | Hous.-Culmore | Independent | , | |||
| Meehan | 1903 | 7/17 | Schenectady Frog Alleys | New York State League | , | ||
| Harry Meek | meek--001her | 1903 | 68 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Jouett Meekin | meekin002jou | 1903 | 5/7-5/12 | Evansville River Rats | Central League | , | |
| Jouett Meekin | meekin002jou | 1903 | 5/13-7/2 | Umpire | Central League | , | |
| Meese | 1903 | 4/30- | Dayton | Inland Empire League | , | ||
| Billy Mehl | mehl--001wil | 1903 | 58 g. | Fargo | Northern League | , | |
| Kid Melcher | melche001--- | 1903 | Camden NJ | Independent | , | ||
| Bill Mellor | mellor001wil | 1903 | 4/22-9/20 | Columbus Senators | American Association | , | |
| John Menefee | menefe001joh | 1903 | - 9/7 | 22 g. | Chicago | National League | Chicago, IL |
| Tom Menefee | menefe001tho | 1903 | Umpire | Pacific National League | , | ||
| Mercer | mercer008--- | 1903 | 6/11-7/1+ | Red Cloud | Central Nebraska League | , | |
| Elmer Meredith | meredi001elm | 1903 | 4/22-9/21 | Milwaukee Brewers | American Association | , | |
| Horace Merkle | merkle001hor | 1903 | 5/29 | Helena Senators | Pacific National League | , | |
| Merrick | 1903 | 6//3-8/17 | Umpire | Connecticut League | , | ||
| Ed Merrill | merril001--- | 1903 | Beloit College | College | , | ||
| Ed Merrill | merril001--- | 1903 | 11 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Garnett Merrill | merril002gar | 1903 | +8/14-8/21+ | Columbia | Tennessee-Alabama League | , | |
| Merritt | merrit009--- | 1903 | 8/20-8/25+ | Pulaski | Tennessee-Alabama League | , | |
| Bill Merritt | merrit001bil | 1903 | 5/6-9/11 | Lowell Tigers | New England League | , | |
| George Merritt | merrit002geo | 1903 | -5/26 | 9 g. | Pittsburgh | National League | Pittsburgh, PA |
| George Merritt | merrit002geo | 1903 | 6/18-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| George Merritt | merrit002geo | 1903 | 7/20-7/29 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| George Merritt | merrit002geo | 1903 | 8/3-9/26 | Jersey City Skeeters | Eastern League | , | |
| Sidney Merryman | merrym001sid | 1903 | 5/1-9/14 | Marion Oilworkers | Central League | , | |
| John Mertens | merten002joh | 1903 | 13 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Sam Mertes | mertes001sam | 1903 | 138 g. | New York | National League | New York, NY | |
| Leo Mesmer | mesmer001leo | 1903 | 4/28-7/1 | Umpire | Western League | , | |
| Leo Mesmer | mesmer001leo | 1903 | 7/18-8/1 | Umpire | American Association | , | |
| Jack Messerly | messer001joh | 1903 | 105 g. | Oakland Oaks | Pacific Coast League | , | |
| Jack Messerly | messer001joh | 1903 | 9 g. | Portland Browns | Pacific Coast League | , | |
| Jack Messerly | messer001joh | 1903 | 4/14-7/3+ | Los Angeles | Pacific National League | , | |
| Tom Messitt | messit001tom | 1903 | 4/28-9/17 | Kansas City Blue Stockings | Western League | , | |
| Metcalf | 1903 | Yale Univ. | College | , | |||
| Metcalf | 1903 | Cottage City | Independent | , | |||
| James Metcalf | metcal002jam | 1903 | 5/21-8/30 | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Edward Metz | metz--000edd | 1903 | +5/28-6/13 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Edward Metz | metz--000edd | 1903 | Canton SD | Independent | , | ||
| Meyer | meyer-009--- | 1903 | 7/22 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Meyers | meyers045--- | 1903 | 7/7 | Dayton Veterans | Central League | , | |
| Arthur Meyers | meyers021--- | 1903 | 5/3-5/11 | Dayton Veterans | Central League | , | |
| Arthur Meyers | meyers021--- | 1903 | 13 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Arthur Meyers | meyers021--- | 1903 | Waterloo IA | Independent | , | ||
| George Meyers | meyers001geo | 1903 | Arkansas State League | , | |||
| Middleton | 1903 | 5/28-5/30 | Galveston Sand Crabs | South Texas League | , | ||
| Charlie Middleton | middle002cha | 1903 | Greenville Grays | Cotton States League | , | ||
| Charlie Middleton | middle002cha | 1903 | 46 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| William Miles | 1903 | 5/2-5/16 | Concord Marines | New England League | , | ||
| Miller | miller247--- | 1903 | 7/7-7/11+ | Joplin Miners | Missouri Valley League | , | |
| Miller | miller248--- | 1903 | 8/26-8/27 | Iola Gaslighters | Missouri Valley League | , | |
| Al Miller | miller005al- | 1903 | 4/26-9/20 | Memphis Egyptians | Southern Association | , | |
| Charles Miller | miller032cha | 1903 | 4/16-4/24 | Spokane Indians | Pacific National League | , | |
| Charles Miller | miller032cha | 1903 | 4/29-7/14+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland/SLC, | |
| Chris Miller | miller002chr | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Dan Miller | 1903 | College | , | ||||
| Dan Miller | 1903 | Altoona PA | Independent | , | |||
| Doc Miller | miller016jam | 1903 | 5/9 | Toronto Maple Leafs | Eastern League | , | |
| Doc Miller | miller004roy | 1903 | 5/29-9/11 | Manchester | New England League | , | |
| Dusty Miller | miller004cha | 1903 | 4/25-9/20 | Memphis Egyptians | Southern Association | , | |
| Dusty Miller | miller001dak | 1903 | 4/28-7/7 | Kansas City Blue Stockings | Western League | , | |
| Dusty Miller | miller001dak | 1903 | 7/10-9/17 | Omaha Indians | Western League | , | |
| Eric Miller | miller021--- | 1903 | +8/24+ | Huntsville | Tennessee-Alabama League | , | |
| Eric Miller | miller021--- | 1903 | Decatur | Tennessee-Alabama League | , | ||
| F. C. Miller | miller002f-- | 1903 | 8/9-9/11 | Des Moines Undertakers | Western League | , | |
| George Miller | miller005geo | 1903 | 5/1-9/16 | Dayton Veterans | Central League | , | |
| George Miller | miller001geo | 1903 | 7/25-9/15 | Wheeling Stogies | Central League | , | |
| H. F. Miller | 1903 | Monroe Hill Citys | Cotton States League | , | |||
| Harry Miller | miller013har | 1903 | 79 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Jack Miller | miller011jac | 1903 | 4/30- | Colfax | Inland Empire League | , | |
| Jack Miller | miller011jac | 1903 | Salem | Willamette Valley | Salem, OR | ||
| Jim Miller | miller016jam | 1903 | 4/30-9/26 | Toronto Maple Leafs | Eastern League | , | |
| Kohly Miller | miller001koh | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| Roscoe Miller | miller001ros | 1903 | 15 g. | New York | National League | New York, NY | |
| Samuel Miller | miller001sam | 1903 | 5/9-9/12 | Springfield Ponies | Connecticut League | , | |
| W. Glen Miller | miller001dak | 1903 | 8/27-9/17 | Omaha Indians | Western League | , | |
| Walter Miller | miller005wal | 1903 | 7/10-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| William Miller | miller005w-- | 1903 | Marysville KS | Independent | , | ||
| William Miller | miller005w-- | 1903 | 7/3-7/14 | Corsicana Oil Citys | Texas League | , | |
| Pat Millerick | miller002pat | 1903 | 4/28-9/18 | Birmingham Barons | Southern Association | , | |
| Milligan | millig010--- | 1903 | 6/11- | Red Cloud | Central Nebraska League | , | |
| Billy Milligan | millig002wil | 1903 | 5/1-9/26 | Buffalo Bisons | Eastern League | , | |
| Lynn Mills | mills-001lyn | 1903 | 4/24-5/6+ | Spokane Indians | Pacific National League | , | |
| Lynn Mills | mills-001lyn | 1903 | 5/29-6/14 | Colfax | Inland Empire League | , | |
| Sam Mills | mills-001lyn | 1903 | no g. | Spokane Indians | Pacific National League | , | |
| Willie Mills | mills-004wil | 1903 | 4/30-6/15 | Baltimore Orioles | Eastern League | , | |
| Willie Mills | mills-004wil | 1903 | 6/19-8/8 | Rochester Bronchos | Eastern League | , | |
| Willie Mills | mills-004wil | 1903 | 8/12-9/25 | Toronto Maple Leafs | Eastern League | , | |
| Arthur Millsap | millsa001art | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Milton | milton007--- | 1903 | 6/19 | Holyoke Paperweights | Connecticut League | , | |
| Larry Milton | milton001sam | 1903 | 5/7 | St. Louis | National League | St. Louis, MO | |
| Larry Milton | milton001sam | 1903 | 5/17-7/19 | Omaha Indians | Western League | , | |
| Larry Milton | milton001sam | 1903 | 7/29-9/14 | Kansas City Blue Stockings | Western League | , | |
| Cotton Minahan | minaha001edm | 1903 | Manhattan Col. | College | , | ||
| Cotton Minahan | minaha001edm | 1903 | +8/17+ | Plattsburgh | Northern New York League | , | |
| Cotton Minahan | minaha001edm | 1903 | +9/7+ | Elmira-FatherMathew | Independent | , | |
| Paul Minish | minish001pau | 1903 | no g. | Evansville River Rats | Central League | , | |
| Charles Minor | minor-002c-- | 1903 | 4/30-9/15 | Evansville River Rats | Central League | , | |
| Jack Miran | miran-001joh | 1903 | 5/9-9/15 | Utica Pent-Ups | New York State League | , | |
| Mitchell | mitche053--- | 1903 | 4/27-5/6 | Birmingham Barons | Southern Association | , | |
| Mitchell | 1903 | 5/24 | Albany Senators | New York State League | , | ||
| Mitchell | mitche067--- | 1903 | 9/11-9/12 | New London Whalers | Connecticut League | , | |
| Fred Mitchell | mitche005fre | 1903 | 29 g. | Philadelphia | National League | Philadelphia, PA | |
| Mike Mitchell | mitche002mic | 1903 | 5/18-9/20 | Syracuse Stars | New York State League | , | |
| Homer Mock | mock--001hom | 1903 | 4/24-5/2 | Toledo Mud Hens | American Association | , | |
| Homer Mock | mock--001hom | 1903 | 5/17-8/3 | Schenectady Frog Alleys | New York State League | , | |
| Homer Mock | mock--001hom | 1903 | 8/24-9/20 | Albany Senators | New York State League | , | |
| Modene | 1903 | Newburgh Taylor-mades | Hudson River League | , | |||
| Frank Moffett | moffet001fra | 1903-04 | U. of Tennessee | College | , | ||
| Frank Moffett | moffet001fra | 1903 | Knoxville | Independent | , | ||
| Elmer Moffitt | moffit001elm | 1903 | 4/30-9/13 | South Bend Greens | Central League | , | |
| Kid Mohler | mohler001kid | 1903 | 4/30-7/5 | Denver Grizzlies | Western League | , | |
| Kid Mohler | mohler001kid | 1903 | 115 g. | Seattle Siwashes | Pacific Coast League | , | |
| Carlton Molesworth | molesw001car | 1903 | 4/27-9/19 | Montgomery Black Sox | Southern Association | , | |
| Jose Molina | 1903-07 | Cuba Ls | , | ||||
| Monahan | monaha009--- | 1903 | 5/29 | Butte Miners | Pacific National League | , | |
| Monroe | monroe012--- | 1903 | 6/23 | Evansville River Rats | Central League | , | |
| W. Monroe | 1903 | 8/1-8/2 | Colorado Springs Millionaires | Western League | , | ||
| Milton Montgomery | montgo001mil | 1903 | Wilmerding PA | Independent | , | ||
| Roy Montgomery | montgo001roy | 1903 | 4/25-9/20 | New Orleans Pelicans | Southern Association | , | |
| Mooney | 1903 | 2 g. | Mobile | Interstate League | , | ||
| Carl Moore | moore-007car | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| Carl Moore | moore-007car | 1903 | Keokuk | Iowa League | , | ||
| Earl Moore | moore-001ear | 1903 | 29 g. | Cleveland | American League | Cleveland, OH | |
| Ed Moore | moore-002ed- | 1903 | 6/8-7/16+ | McCook | Central Nebraska League | , | |
| Frederick Moore | moore-001fre | 1903 | 10 g. | Brewton | Interstate League | , | |
| J. F. Moore | 1903 | 5/15 | Syracuse Stars | New York State League | , | ||
| John Moore | moore-009joh | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| Paul Moore | moore-001pau | 1903 | 15 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Shef Moore | moore-001s-- | 1903 | Corning NY | Independent | , | ||
| Wade Moore | moore-001wad | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| James Moorhead | moorhe001jam | 1903 | 5/1-9/12 | Fall River Indians | New England League | , | |
| Charles Morales | morale001cha | 1903 | 4/25-5/30 | San Antonio Bronchos | South Texas League | , | |
| Augie Moran | moran-002aug | 1903 | MLB Umpire | National League | , | ||
| Bill Moran | moran-001bil | 1903 | 4/22-6/10 | Umpire | American Association | , | |
| Charles Moran | moran-003cha | 1903 | 4/29- | 98 g. | Washington | American League | Washington, DC |
| Charlie Moran | moran-002cha | 1903 | 4/26-8/25 | Dallas Giants | Texas League | , | |
| Charlie Moran | moran-002cha | 1903 | 9/9-10/4 | St. Louis | National League | St. Louis, MO | |
| Cliff Moran | 1903 | 6/14-7/13 | Umpire | Central League | , | ||
| Pat Moran | moran-002pat | 1903 | Boston | National League | Boston, MA | ||
| Lew Moren | moren-001lew | 1903 | Duquesne Univ | College | , | ||
| Lew Moren | moren-001lew | 1903 | 9/21 | Pittsburgh | National League | Pittsburgh, PA | |
| Amos Morgan | morgan001amo | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Cy Morgan | morgan003har | 1903 | 5/1-9/10 | Fall River Indians | New England League | , | |
| Cy Morgan | morgan003har | 1903 | 9/18- | 2 g. | St. Louis | American League | St. Louis, MO |
| Ezra Morgan | morgan001ezr | 1903 | 5/7-5/14 | Bridgeport Orators | Connecticut League | , | |
| Ezra Morgan | morgan001ezr | 1903 | 5/18-5/20 | Meriden Silverites | Connecticut League | , | |
| Ezra Morgan | morgan001ezr | 1903 | 6/3-6/10 | Holyoke Paperweights | Connecticut League | , | |
| Red Morgan | morgan003jam | 1903 | Georgetown Univ | College | , | ||
| Ed Moriarty | moriar001edw | 1903 | 5/2-9/22 | Newark Sailors | Eastern League | , | |
| George Moriarty | moriar003geo | 1903 | 45 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| George Moriarty | moriar003geo | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| George Moriarty | moriar003geo | 1903 | 9/27 | Chicago | National League | Chicago, IL | |
| Morris | morris045--- | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Morris | morris001ed- | 1903 | 2 g. | Superior Longshoremen | Northern League | , | |
| Morris | morris063--- | 1903 | 8/17 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Ed Morris | morris001ed- | 1903 | 6/11-9/8 | Superior Longshoremen | Northern League | , | |
| Jack Morris | morris001sam | 1903 | 5/10-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Kid Morris | morris010wil | 1903 | no g. | Dayton Veterans | Central League | , | |
| S. Morris | morris010joh | 1903 | 5/11 | San Antonio Bronchos | South Texas League | , | |
| Samuel Morris | morris001ed- | 1903 | Chemawn | School | , | ||
| Samuel Morris | morris001ed- | 1903 | Salem | Willamette Valley | Salem, OR | ||
| Samuel Morris | morris001ed- | 1903 | +8/5+ | 6 g. | Portland Browns | Pacific Coast League | , |
| Samuel Morris | morris001sam | 1903 | 1 g. | Seattle Siwashes | Pacific Coast League | , | |
| Walter Morris | morris010joh | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| Bill Morrison | morris008wil | 1903 | 4/28-9/13 | Des Moines Undertakers | Western League | , | |
| John Morrison | morris014joh | 1903 | 5/7-9/12 | Hartford Senators | Connecticut League | , | |
| John Morrison | morris015joh | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| John Morrison | morris015joh | 1903 | no g. | Duluth Cardinals | Northern League | , | |
| Dennis Morrissey | 1903 | 5/7-9/12 | Norwich Reds | Connecticut League | , | ||
| Frank Morrissey | morris003mic | 1903 | 5/2-9/12 | Manchester | New England League | , | |
| Jack Morrissey | morris016joh | 1903 | -7/6 | 27 g. | Cincinnati | National League | Cincinnati, OH |
| Jack Morrissey | morris016joh | 1903 | 7/12-8/9 | Columbus Senators | American Association | , | |
| Jack Morrissey | morris016joh | 1903 | 8/19-9/12 | Lawrence Colts | New England League | , | |
| William Morrow | morrow002wil | 1903 | Roseburg | Willamette Valley | Roseburg, OR | ||
| Charles Morse | morse-001cha | 1903 | 5/8-9/16 | Ilion Typewriters | New York State League | , | |
| Frank Morse | morse-001fra | 1903 | Greenville Grays | Cotton States League | , | ||
| Frank Morse | morse-001fra | 1903 | 8/10-9/2 | Atlanta Crackers | Southern Association | , | |
| Pete Morton | morton001pet | 1903 | 5/2-8/2 | Joplin Miners | Missouri Valley League | , | |
| Pete Morton | morton001pet | 1903 | 8/27-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Walter Moser | moser-001wal | 1903 | +3/17+ | Hickory NC | Independent | , | |
| Harry Moses | 1903 | 5/28 | Atlanta Crackers | Southern Association | , | ||
| Doc Moskiman | moskim001wil | 1903 | 135 g. | Oakland Oaks | Pacific Coast League | , | |
| Charles Moss | moss--003cha | 1903 | 4/27-9/20 | Nashville Volunteers | Southern Association | , | |
| Anson Mott | mott--002ans | 1903 | Marysville KS | Independent | , | ||
| Banks Moulder | moulde001ban | 1903 | 7/9-7/11 | Corsicana Oil Citys | Texas League | , | |
| Mike Mowrey | mowrey001har | 1903 | York PA | Independent | , | ||
| Arthur Moyne | moyne-001--- | 1903 | 5/10-5/24 | Centralia Midgets | Southwest Washington League | , | |
| Neal Moynihan | moynih001nea | 1903 | 4/25- | Fort Worth Panthers | Texas League | , | |
| Neal Moynihan | moynih001nea | 1903 | -8/26 | Paris Parasites/Waco Steers | Texas League | Paris/Waco, | |
| Milo Mucklestone | muckle001mil | 1903 | U. of Wisconsin | College | , | ||
| Milo Mucklestone | muckle001mil | 1903 | 44 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Walter Mueller | muelle002wal | 1903 | 5/20-7/13 | Duluth Cardinals | Northern League | , | |
| Walter Mueller | muelle002wal | 1903 | 7/16-9/20 | Milwaukee Brewers | American Association | , | |
| Mulcahy | 1903 | 9/15 | Ilion Typewriters | New York State League | , | ||
| Mulhaupt | 1903 | 9/16 | Nashville Volunteers | Southern Association | , | ||
| Mulholland | mulhol000--- | 1903 | 7/31 | Haverhill Hustlers | New England League | , | |
| Cy Mulkey | mulkey001cyr | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Cy Mulkey | mulkey001cyr | 1903 | 6/26-8/25 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Frank Mullane | mullan001fra | 1903 | 5/20-9/8 | Grand Forks Forkers | Northern League | , | |
| Tom Mullane | 1903 | 7/5-7/10 | Umpire | Western League | , | ||
| Tony Mullane | mullan001ton | 1903 | 4/22-9/21 | Umpire | American Association | , | |
| Dominic Mullaney | mullan002dom | 1903 | 68 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Ed Mullaney | mullan001edw | 1903 | 5/5-5/13 | Providence Grays | Eastern League | , | |
| Ed Mullaney | mullan001edw | 1903 | 5/30-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Ed Mullaney | mullan001edw | 1903 | 6/26-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Jim Mullen | mullin001jam | 1903-04 | Manhattan Col | College | , | ||
| Otho Mullen | mullen010--- | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Max Muller | muller002max | 1903 | 101 g. | Butte Miners | Pacific National League | , | |
| Max Muller | muller002max | 1903 | Helena Senators | Pacific National League | , | ||
| Max Muller | muller002max | 1903 | San Francisco | California State League | , | ||
| W. Muller | muller001w-- | 1903 | San Francisco | California State League | , | ||
| George Mulligan | mullig000geo | 1903 | 5/8-5/14 | Springfield Ponies | Connecticut League | , | |
| Arthur Mullin | mullin001art | 1903 | 5/2-9/15 | Dayton Veterans | Central League | , | |
| John Mullin | mullin001joh | 1903 | 6/3-6/17 | New Orleans Pelicans | Southern Association | , | |
| John Mullin | mullin001joh | 1903 | Atlantic City NJ | Independent | , | ||
| Dick Mulroy | 1903 | 9/25-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | ||
| Gustave Munch | 1903 | Memphis Egyptians | Southern Association | , | |||
| Munn | 1903 | +6/16-6/17+ | Red Cloud | Central Nebraska League | , | ||
| Henry Munsell | munsel000hen | 1903-05 | U. Michigan | College | , | ||
| Red Murch | murch-001rob | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Red Murch | murch-001rob | 1903 | 1 g. | Huntsville AL | Independent | , | |
| Simmy Murch | murch-001sim | 1903 | 5/1- | Haverhill Hustlers | New England League | , | |
| Simmy Murch | murch-001sim | 1903 | -8/15 | Lawrence Colts | New England League | , | |
| D. H. Murden | 1903 | Ossining/Catskill | Hudson River League | Ossining, | |||
| Wilbur Murdoch | murdoc001wil | 1903 | 217 g. | Oakland Oaks | Pacific Coast League | , | |
| Murdock | 1903 | 6/21 | Aberdeen Pippins | Southwest Washington League | , | ||
| Tim Murnane | murnan001tim | 1903 | President | New England League | , | ||
| Murphy | 1903 | Harvard | College | , | |||
| Murphy | 1903 | New London NH | Independent | , | |||
| Murphy | murphy112--- | 1903 | 6/27-6/29 | Norwich Reds | Connecticut League | , | |
| Murphy | 1903 | 6/8-6/10 | Atlanta Crackers | Southern Association | , | ||
| Connie Murphy | murphy002con | 1903 | 5/1-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Connie Murphy | murphy002con | 1903 | 6/26- | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Connie Murphy | murphy002con | 1903 | -9/12 | Lawrence Colts | New England League | , | |
| Danny Murphy | murphy006dan | 1903 | Philadelphia | American League | Philadelphia, PA | ||
| Dave Murphy | murphy001dav | 1903 | 5/7-6/2 | Norwich Reds | Connecticut League | , | |
| E. Murphy | 1903 | 5/2-5/6 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | ||
| Ed Murphy | murphy005edw | 1903 | -9/19 | 24 g. | St. Louis | National League | St. Louis, MO |
| Frank Murphy | murphy004fra | 1903 | 5/13-9/12 | New London Whalers | Connecticut League | , | |
| Guy Murphy | murphy002guy | 1903 | 4/30-5/25 | Fort Wayne Railroaders | Central League | , | |
| Guy Murphy | murphy002guy | 1903 | 6/1-7/18+ | Duluth Cardinals | Northern League | , | |
| Howard Murphy | murphy001how | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| John Murphy | murphy015joh | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| John Murphy | murphy015joh | 1903 | -9/12 | Haverhill Hustlers | New England League | , | |
| John Murphy | murphy015joh | 1903 | Detroit | American League | Detroit, MI | ||
| John Murphy | murphy004joh | 1903 | +7/6-8/6+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Thomas Murphy | murphy001cor | 1903 | 4/25-7/15 | Little Rock Travelers | Southern Association | , | |
| Yale Murphy | murphy001yal | 1903 | Yale Univ. | College | , | ||
| Yale Murphy | murphy001yal | 1903 | 7/13-7/29 | New Haven Blues | Connecticut League | , | |
| Murray | murray066--- | 1903 | 7/9-9/19 | Joplin Miners | Missouri Valley League | , | |
| Alexander Murray | murray001ale | 1903 | Newark OH | Independent | , | ||
| Billy Murray | murray007wil | 1903 | 4/30-9/26 | Jersey City Skeeters | Eastern League | , | |
| Ernest Murray | murray001ern | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| F. C./P. C. Murray | 1903 | Ossining/Catskill | Hudson River League | Ossining, | |||
| James Murray | murray007jam | 1903 | Peekskill | Hudson River League | , | ||
| James Murray | murray007jam | 1903 | Saugerties | Hudson River League | , | ||
| Jim Murray | murray008jam | 1903 | 5/13-9/12 | Manchester | New England League | , | |
| Jim Murray | murray008jam | 1903 | 9/18-9/26 | Toronto Maple Leafs | Eastern League | , | |
| John Murray | murray012joh | 1903 | Corning NY | Independent | , | ||
| Red Murray | murray002joh | 1903-04 | Lock Haven Univ. | College | , | ||
| William Mutter | mutter001wil | 1903 | +8/9+ | Calumet MI | Independent | , | |
| John Myatt | myatt-002joh | 1903 | 4/25-7/8 | Beaumont Oil Gushers | South Texas League | , | |
| Myer | myer--004--- | 1903 | 7/7 | Dayton Veterans | Central League | , | |
| Bade Myers | myers-002wil | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| Bert Myers | myers-001ber | 1903 | 5/16-6/15 | Baltimore Orioles | Eastern League | , | |
| Bert Myers | myers-001ber | 1903 | 7/1-9/7 | Rochester Bronchos | Eastern League | , | |
| James Myers | myers-003j-- | 1903 | Waterloo IA | Independent | , | ||
| John Myers | meyers004joh | 1903 | 4/30-9/16 | Marion Oilworkers | Central League | , | |
| Tommy Mylett | mylett002tho | 1903 | 5/8-9/20 | Utica Pent-Ups | New York State League | , | |
| Phil Nadeau | nadeau001phi | 1903 | 204 g. | Portland Browns | Pacific Coast League | , | |
| Nagle | nagle-004--- | 1903 | Portland Browns | Pacific Coast League | , | ||
| Nagle | 1903 | Goldsboro | East Carolina League | , | |||
| Judge Nagle | nagle-002wal | 1903 | San Francisco | California State League | , | ||
| Paul Nagle | nagle-001lef | 1903 | 5/3-6/14 | Pendleton | Inland Empire League | , | |
| Paul Nagle | nagle-001lef | 1903 | +6/23-8/12+ | Helena Senators | Pacific National League | , | |
| Richard Nallin | nallin001ric | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| William Nance | nance-001wil | 1903 | 4/22-9/21 | Kansas City Cowboys | American Association | , | |
| John Nash | nash--001joh | 1903 | Ogden UT | Independent | , | ||
| John Nash | nash--001joh | 1903 | Evanston WY | Independent | , | ||
| Billy Nattress | nattre001wil | 1903 | 4/30-9/26 | Buffalo Bisons | Eastern League | , | |
| Offa Neal | neal--002the | 1903 | 17 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Offa Neal | neal--002the | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| George Needham | needha001geo | 1903 | 5/8-9/20 | Utica Pent-Ups | New York State League | , | |
| Tom Needham | needha001tho | 1903 | 107 g. | Altoona PA | Independent | , | |
| William Nefzger | nefzge000wil | 1903 | Coquille OR | Independent | , | ||
| Edward Nehr | neher-001ed- | 1903 | 5/29-5/30 | Duluth Cardinals | Northern League | , | |
| Edward Nehr | neher-001ed- | 1903 | 6/1-7/24 | Superior Longshoremen | Northern League | , | |
| Edward Nehr | neher-001ed- | 1903 | 7/27-7/28 | Grand Forks Forkers | Northern League | , | |
| Fred Nehring | nehrin001fre | 1903 | Centralia WA | Independent | , | ||
| Fred Neiman | neiman001fre | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| Neitzer | 1903 | 5/2-5/3 | St. Joseph Saints | Western League | , | ||
| Nelson | 1903 | 7/3-8/2 | Umpire | Central League | , | ||
| Clarence Nelson | nelson001cla | 1903 | 8/29 | Houston Buffaloes | South Texas League | , | |
| Henry Nelson | nelson001hen | 1903 | 6/3-6/20 | Norwich Reds | Connecticut League | , | |
| Ray Nelson | nelson001ray | 1903 | 6/16-6/19 | Holyoke Paperweights | Connecticut League | , | |
| Ray Nelson | nelson001ray | 1903 | 6/22-6/30 | Springfield Ponies | Connecticut League | , | |
| William Nelson | nelson004wil | 1903 | 4/28-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Mike Neville | nevill001mic | 1903 | StL-White Seals | Independent | , | ||
| Michael Nevins | nevins001mic | 1903 | Petaluma | California State League | , | ||
| Frank Newberry | 1903 | Lafayette Col. | College | , | |||
| Hiram Newell | newell002har | 1903 | +5/19-5/31+ | Colfax | Inland Empire League | , | |
| Hiram Newell | newell002har | 1903 | Roseburg | Willamette Valley | Roseburg, OR | ||
| Horace Newenham | newenh001hor | 1903 | 6/5-7/31 | Newark Sailors | Eastern League | , | |
| Ira Newick | newick001ira | 1903 | +6/17-7/25+ | Lynn MA | Independent | , | |
| Ira Newick | newick001ira | 1903 | 7/29 | Haverhill Hustlers | New England League | , | |
| Otto Newlin | newlin001ott | 1903 | 4/23-9/15 | Indianapolis Indians | American Association | , | |
| Newman | newman025--- | 1903 | 8/19 | Hartford Senators | Connecticut League | , | |
| John Newman | newman001joh | 1903 | 92 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Spri, | |
| John Newman | newman001joh | 1903 | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | ||
| Harry Newmeyer | newmey001har | 1903 | 5/1-9/17 | Colorado Springs Millionaires | Western League | , | |
| Harry Newmeyer | newmey001har | 1903 | 9/24-10/3 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Pat Newnam | newnam001pat | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| Al Newnham | newnha001alf | 1903 | +8/13+ | Hornersville NY | Independent | , | |
| Al Newnham | newnha001alf | 1903 | 9/3-9/9 | Ilion Typewriters | New York State League | , | |
| Tom News | news--001tho | 1903 | 4/30-9/15 | Evansville River Rats | Central League | , | |
| Albert Newton | newton001alb | 1903 | 5/1-9/12 | Concord Marines | New England League | , | |
| Albert Newton | newton001alb | 1903 | Lebanon PA | Independent | , | ||
| Doc Newton | newton001eus | 1903 | 58 g. | Los Angeles Angels | Pacific Coast League | , | |
| Doc Newton | newton001eus | 1903 | 1 g. | Portland Browns | Pacific Coast League | , | |
| Neylon | 1903 | 7/1-7/11 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | ||
| Simon Nicholls | nichol001sim | 1903 | 9/18- | 2 g. | Detroit | American League | Detroit, MI |
| Art Nichols | nichol001art | 1903 | St. Louis | National League | St. Louis, MO | ||
| Art Nichols | nichol001art | 1903 | 7/14-7/19 | Indianapolis Indians | American Association | , | |
| Ernest Nichols | 1903 | +3/7 | SF-Reliance | Independent | , | ||
| Ernest Nichols | 1903 | 25 g. | Spokane Indians | Pacific National League | , | ||
| George Nichols | nichol001g-- | 1903 | 7/13 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Ira Nichols | nichol032--- | 1903 | 5/2-5/4+ | Springfield Midgets | Missouri Valley League | , | |
| Ira Nichols | nichol032--- | 1903 | 6/22-7/11+ | Joplin Miners | Missouri Valley League | , | |
| Kid Nichols | nichol006cha | 1903 | 5/2-9/13 | Kansas City Blue Stockings | Western League | , | |
| Walt Nichols | nichol001w-- | 1903 | 6/4-9/12 | Bridgeport Orators | Connecticut League | , | |
| Al Nickell | nickel001al- | 1903 | 4/28-8/25 | Dallas Giants | Texas League | , | |
| Al Nickell | nickel001al- | 1903 | 6/10-6/15 | New Orleans Pelicans | Southern Association | , | |
| Harry Nickens | nicken001har | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| Harry Nickens | nicken001har | 1903 | +5/20+ | Nashv.-Maroons | Independent | , | |
| Harry Nickens | nicken001har | 1903 | +6/10+ | Columbia TN | Independent | , | |
| Harry Nickens | nicken001har | 1903 | 7/15-9/20 | Nashville Volunteers | Southern Association | , | |
| Hugh Nicol | nicol-001hug | 1903 | 5/1-9/13 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Niel | 1903 | 9/6 | Kansas City Cowboys | American Association | , | ||
| Nihil | nihil-000--- | 1903 | 9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Tom Niland | niland001tom | 1903 | +8/15+ | Milford | Independent | , | |
| Harry Niles | niles-001her | 1903 | 5/8-9/20 | Binghamton Bingoes | New York State League | , | |
| George Nill | nill--001geo | 1903 | 4/28-9/17 | Colorado Springs Millionaires | Western League | , | |
| Bernard Nippert | nipper001ben | 1903 | 5/1-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Bernard Nippert | nipper001ben | 1903 | 5/30-6/4 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Bernard Nippert | nipper001ben | 1903 | Lima OH | Independent | , | ||
| Noble | 1903 | U. Pennsylvania | College | , | |||
| Noble | 1903 | Idlewild NH | Independent | , | |||
| Bert Noblett | noblet001j-- | 1903 | 442 ab | Monroe Hill Citys | Cotton States League | , | |
| George Noblit | noblit001geo | 1903 | 5/1-9/12 | Concord Marines | New England League | , | |
| John Nolan | nolan-030--- | 1903 | Massillon OH | Independent | , | ||
| Thomas Nolan | 1903 | Altoona PA | Independent | , | |||
| Peter Nolden | nolden001pet | 1903 | 5/16-6/19 | Memphis Egyptians | Southern Association | , | |
| Peter Nolden | nolden001pet | 1903 | +7/6-9/8 | Duluth Cardinals | Northern League | , | |
| Rufus Nolley | nolley001ruf | 1903 | +8/20-9/8+ | Columbia | Tennessee-Alabama League | , | |
| Joe Nonemaker | nonama001jos | 1903 | 5/3-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Joe Nonemaker | nonama001jos | 1903 | 5/30-6/15 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Pete Noonan | noonan001pet | 1903 | Lebanon NH | Independent | , | ||
| William Noone | noone-000bil | 1903 | Seton Hall Univ | College | , | ||
| William Noone | noone-000bil | 1903 | 7/27 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Frank Norcom | norcom001fra | 1903 | 4/25-9/20 | Shreveport Giants | Southern Association | , | |
| Lou Nordyke | nordyk001lou | 1903 | 4/14-9/29+ | Spokane Indians | Pacific National League | , | |
| Cuyler North | 1903 | Kalamazoo MI | Independent | , | |||
| Samuel North | north-001sam | 1903 | Pittsburg Coal Diggers | Missouri Valley League | , | ||
| A. H. Northcutt | northc001a-- | 1903-05 | +5/23+ | Univ. of Missouri | College | , | |
| Pete Norwood | norwoo000pet | 1903 | 8/11-9/12 | Huntsville | Tennessee-Alabama League | , | |
| Jim Novacek | novace001jam | 1903 | 119 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Harry Noyes | noyes-001har | 1903 | 5/7-9/12 | New London Whalers | Connecticut League | , | |
| Jack Nugent | nugent001joh | 1903 | 5/1-8/3 | Dayton Veterans | Central League | , | |
| Nystrom | nystro000--- | 1903 | +6/17-7/24 | Minden | Central Nebraska League | , | |
| O'Banion | obanio000--- | 1903 | +6/24-7/16+ | Giltner | Central Nebraska League | , | |
| O'Brien | obrien109--- | 1903 | 5/12-5/14 | Holyoke Paperweights | Connecticut League | , | |
| Dan O'Brien | noone-000bil | 1903 | 5/10-5/13 | Schenectady Frog Alleys | New York State League | , | |
| Dan O'Brien | noone-000bil | 1903 | 6/10-6/27 | Hartford Senators | Connecticut League | , | |
| Dan O'Brien | obrien005dan | 1903 | 6/30-7/6 | Springfield Ponies | Connecticut League | , | |
| Frank O'Brien | obrien003fra | 1903 | Oakland Reliance | California State League | , | ||
| Frank O'Brien | obrien003fra | 1903 | 2 g. | San Francisco Seals | Pacific Coast League | , | |
| Frank O'Brien | 1903 | Milw.-Sentinel | Independent | , | |||
| Frank O'Brien | 1903 | 9/10 | Kansas City Cowboys | American Association | , | ||
| Frederick O'Brien | obrien001fre | 1903 | Manhattan Col. | College | , | ||
| Frederick O'Brien | obrien001fre | 1903 | St. Albans | Northern New York League | , | ||
| George O'Brien | obrien001geo | 1903 | 8/3-9/12 | Haverhill Hustlers | New England League | , | |
| Hugh O'Brien | obrien001h-- | 1903 | Cotton States League | , | |||
| Hugh O'Brien | obrien001h-- | 1903 | 8/11-9/12 | Decatur | Tennessee-Alabama League | , | |
| Jack O'Brien | obrien005joh | 1903 | -9/28 | 96 g. | Boston | American League | Boston, MA |
| Jack O'Brien | obrien006jac | 1903 | Salt Lake-Indep | Independent | , | ||
| James O'Brien | obrien001tom | 1903 | 4/27-7/20 | Birmingham Barons | Southern Association | , | |
| John O'Brien | obrien009joh | 1903 | 5/1-9/26 | Newark Sailors | Eastern League | , | |
| Michael O'Brien | 1903 | Laconia | Independent | , | |||
| Mickey O'Brien | 1903 | 11 g. | Brewton | Interstate League | , | ||
| Pete O'Brien | obrien001pet | 1903 | 4/22-6/26 | Indianapolis Indians | American Association | , | |
| Pete O'Brien | obrien001pet | 1903 | 8/6-9/14 | Indianapolis Indians | American Association | , | |
| Thomas O'Brien | obrien003tho | 1903 | 33 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Tom O'Brien | obrien001tom | 1903 | 4/27-7/20 | Birmingham Barons | Southern Association | , | |
| Tom O'Brien | obrien001tom | 1903 | 9/2-9/20 | Birmingham Barons | Southern Association | , | |
| William O'Brien | obrien007wil | 1903 | 5/4-5/10 | Fort Scott Giants | Missouri Valley League | , | |
| William O'Brien | obrien007wil | 1903 | Fort Scott Giants | Missouri Valley League | , | ||
| O'Connell | oconne026--- | 1903 | 9/10 | Terre Haute Hottentots | Central League | , | |
| O'Connell | 1903 | 9/8-9/16 | Umpire | Central League | , | ||
| Henry O'Connell | 1903 | Watertown WI | Independent | , | |||
| Henry O'Connell | 1903 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |||
| John O'Connell | oconne003joh | 1903 | 5/2-5/8 | Nashville Volunteers | Southern Association | , | |
| John O'Connell | oconne003joh | 1903 | 5/16-9/14 | Fort Wayne Railroaders | Central League | , | |
| John O'Connell | oconne003joh | 1903 | Umpire | Pacific Coast League | , | ||
| O'Connor | 1903 | 7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | ||
| O'Connor | oconno037--- | 1903 | 7/7-7/20 | Hartford Senators | Connecticut League | , | |
| Dan O'Connor | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | |||
| Jack O'Connor | oconno006joh | 1903 | New York | American League | New York, NY | ||
| Jack O'Connor | 1903 | Decatur Commodores | Illinois-Indiana-Iowa League | , | |||
| James O'Connor | 1903 | 5/21-5/26 | Duluth Cardinals | Northern League | , | ||
| Mike O'Connor | oconno003mik | 1903 | 4/25-7/21 | Corsicana Oil Citys | Texas League | , | |
| Paddy O'Connor | oconno004pat | 1903 | 5/8-9/12 | Springfield Ponies | Connecticut League | , | |
| Patrick O'Connor | oconno003pat | 1903 | 41 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Royes O'Connor | oconno001roy | 1903 | Elmira NY | Independent | , | ||
| Charles O'Day | oday--001cha | 1903 | 18 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Willie O'Day | oday--002wil | 1903 | Albany | Willamette Valley | Albany, OR | ||
| Artie O'Dea | odea--001art | 1903 | 5/20-9/8 | Winnipeg Maroons | Northern League | , | |
| Eugene O'Gorman | 1903 | Pottsville | , | ||||
| Eugene O'Gorman | 1903 | Troy Trojans | New York State League | , | |||
| Hal O'Hagan | ohagen001har | 1903 | 4/30-9/26 | Newark Sailors | Eastern League | , | |
| Joseph O'Halloran | 1903 | +5/9+ | Reading PA | Independent | , | ||
| Bill O'Hara | ohara-002wil | 1903 | 198 g. | Oakland Oaks | Pacific Coast League | , | |
| Bill O'Hara | ohara-002wil | 1903 | 7 g. | Seattle Siwashes | Pacific Coast League | , | |
| Dennis O'Hara | ohara-001den | 1903 | Pittsburg College | College | , | ||
| Dennis O'Hara | ohara-001den | 1903 | Newark Sailors | Eastern League | , | ||
| Dennis O'Hara | ohara-001den | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| Dennis O'Hara | ohara-001den | 1903 | -9/12 | Fall River Indians | New England League | , | |
| Kid O'Hara | ohara-001jam | 1903 | 6/22-9/12 | Lawrence Colts | New England League | , | |
| Thomas O'Hare | ohare-001tho | 1903 | 5/5-9/15 | Evansville River Rats | Central League | , | |
| Charley O'Leary | oleary001cha | 1903 | 4/28-9/17 | Des Moines Undertakers | Western League | , | |
| Daniel O'Leary | oleary001dan | 1903 | 102 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Frank O'Leary | oleary001fra | 1903 | South Bend Greens | Central League | , | ||
| George O'Leary | oleary001geo | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| O'Malley | 1903 | 7/4-7/6 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | ||
| O'Neil | oneil-028--- | 1903 | 7/30-8/15 | Hartford Senators | Connecticut League | , | |
| Dan O'Neil | oneill003dan | 1903 | 5/?-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Harry O'Neil | oneil-000har | 1903 | 5/6- | Lawrence Colts | New England League | , | |
| Harry O'Neil | oneil-000har | 1903 | 7/27 | Haverhill Hustlers | New England League | , | |
| Joseph O'Neil | 1903 | 8/20-9/9 | Brockton/New Bedford Whalers | New England League | New Bedford, | ||
| O'Neill | oneill033--- | 1903 | +6/25-7/16+ | Giltner | Central Nebraska League | , | |
| Jack O'Neill | oneill008joh | 1903 | 75 g. | St. Louis | National League | St. Louis, MO | |
| John O'Neill | oneill004wil | 1903 | 4/28-9/17 | Milwaukee Creams | Western League | , | |
| Joseph O'Neill | 1903 | +5/12+ | Reading PA | Independent | , | ||
| Mike O'Neill | oneill002mic | 1903 | 41 g. | St. Louis | National League | St. Louis, MO | |
| Peaches O'Neill | oneill002phi | 1903 | 5/22-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Peaches O'Neill | oneill002phi | 1903 | 5/30-9/16 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Thomas O'Reilly | oreill001tho | 1903 | 5/11-7/16 | Haverhill Hustlers | New England League | , | |
| Jim O'Rourke | orourk003jam | 1903 | 5/12-9/12 | Bridgeport Orators | Connecticut League | , | |
| Jimmy O'Rourke | orourk005jam | 1903 | Yale University | College | , | ||
| Jimmy O'Rourke | orourk005jam | 1903 | 7/1-9/12 | Bridgeport Orators | Connecticut League | , | |
| Tim O'Rourke | orourk003tim | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Odwell | 1903 | 5/9 | Troy Trojans | New York State League | , | ||
| Fred Odwell | odwell001fre | 1903 | 4/22-9/20 | Louisville Colonels | American Association | , | |
| Kid Ogden | ogden-001lou | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| John Okey | 1903 | preseason | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| John Okey | 1903 | +6/21+ | Webster IA | Independent | , | ||
| Oliver | 1903 | Umpire | South Texas League | , | |||
| Oliver | 1903 | Umpire | South Texas League | , | |||
| A. Oliver | 1903 | Saugerties | Hudson River League | , | |||
| Cornelius Ollre | 1903 | Orange TX | Independent | , | |||
| Fred Olmsted | olmest001fre | 1903 | 5/20-8/3 | Duluth Cardinals | Northern League | , | |
| Fred Olmsted | olmest001fre | 1903 | 6/5-7/25+ | Superior Longshoremen | Northern League | , | |
| Hank Olmsted | olmste001hen | 1903 | 4/28-9/13 | 31 g. | Peoria Distillers | Western League | , |
| John? Olson | olson-011--- | 1903 | 21 g. | Superior Longshoremen | Northern League | , | |
| Edward Opfergelt | opferg000edw | 1903 | +4/6+ | Notre Dame | College | , | |
| Edward Opfergelt | opferg000edw | 1903 | 6/22- | Hampton IA | Independent | , | |
| Edward Opfergelt | opferg000edw | 1903 | +7/1+ | Mason City IA | Independent | , | |
| Walter Orbin | orbin-000wal | 1903 | U. Pennsylvania | College | , | ||
| Walter Orbin | orbin-000wal | 1903 | 6/22-7/17 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Walter Orbin | orbin-000wal | 1903 | 7/20-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Ortman | ortman004--- | 1903 | 6/17-6/20+ | Leavenworth White Sox | Missouri Valley League | , | |
| Orton | 1903 | U. Vermont | College | , | |||
| Orton | 1903 | Newport NH | Independent | , | |||
| Arch Osborne | osborn001arc | 1903 | Homestead PA | Independent | , | ||
| Robert Osborne | osborn003rob | 1903 | 18 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Joseph Osment | osment001jos | 1903 | Chat.-Wheland | Independent | , | ||
| Joseph Osment | osment001jos | 1903 | 6 g. | Decatur | Tennessee-Alabama League | , | |
| Joseph Osment | osment001jos | 1903 | 8/15-8/20 | Huntsville | Tennessee-Alabama League | , | |
| Joseph Osment | osment001jos | 1903 | 8/21- | Pulaski | Tennessee-Alabama League | , | |
| Harry Ostdiek | ostdie001hen | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| Champ Osteen | osteen001jam | 1903 | 112 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Champ Osteen | osteen001jam | 1903 | 9/18- | 10 g. | Washington | American League | Washington, DC |
| Frank Ott | ott---002fra | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Otterson | otters000--- | 1903 | 5/7-5/8 | Meriden Silverites | Connecticut League | , | |
| Jim Outcalt | outcal001jam | 1903 | 5/2-5/16 | South Bend Greens | Central League | , | |
| Jim Outcalt | outcal001jam | 1903 | Sisterville VA | Independent | , | ||
| Benjamin Owen | 1903 | Leavenworth White Sox | Missouri Valley League | , | |||
| Frank Owen | owen--001fra | 1903 | Chicago | American League | Chicago, IL | ||
| Arthur Owens | owens-001art | 1903 | 62 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Arthur Owens | owens-001art | 1903 | 9/19 | Indianapolis Indians | American Association | , | |
| Clarence Owens | 1903 | 5/30-7/31 | Umpire | Northern League | , | ||
| Clarence Owens | 1903 | Umpire | Central League | , | |||
| Clarence Owens | 1903 | 8/19-9/17 | Umpire | Western League | , | ||
| Red Owens | owens-003tho | 1903 | 4/22-9/20 | Toledo Mud Hens | American Association | , | |
| Clarence Owsley | owsley001--- | 1903 | 6/15-7/9 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Andy Oyler | oyler-001and | 1903 | 4/22-9/21 | Minneapolis Millers | American Association | , | |
| Ed Pabst | pabst-001ed- | 1903 | 181 g. | San Francisco Seals | Pacific Coast League | , | |
| Dick Padden | padden001ric | 1903 | 29 g. | St. Louis | American League | St. Louis, MO | |
| Luis Padron | padron001lou | 1903 | Habana | Cuban Winter League | , | ||
| Billy Page | page--001wil | 1903 | 5/1-8/29 | Manchester | New England League | , | |
| George Page | page--003geo | 1903 | 4/26-9/20 | Shreveport Giants | Southern Association | , | |
| Jack Page | page--002joh | 1903 | 6/26- 7/1+ | Grand Forks Forkers | Northern League | , | |
| Jack Page | page--002joh | 1903 | +7/12+ | Superior Longshoremen | Northern League | , | |
| Thomas Pagum | pagum-000tho | 1903 | 5/6- | Haverhill Hustlers | New England League | , | |
| Thomas Pagum | pagum-000tho | 1903 | -6/23 | Lawrence Colts | New England League | , | |
| Thomas Pagum | pagum-000tho | 1903 | 8/19-8/24 | Norwich Reds | Connecticut League | , | |
| Allie Paige | paige-002alb | 1903 | New London Whalers | Connecticut League | , | ||
| Fred? Paige | 1903 | Corning NY | Independent | , | |||
| Edward Painter | painte001edw | 1903 | 4/14-6/10+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Paisley | 1903 | 8/2 | Aberdeen Pippins | Southwest Washington League | , | ||
| Palmer | palmer023--- | 1903 | +8/20-9/4+ | Columbia | Tennessee-Alabama League | , | |
| Emilio Palomino | palomi000emi | 1903 | San Francisco | Cuban Winter League | , | ||
| Emil Papenfuss | papenf001emi | 1903 | Wausau WI | Independent | , | ||
| John Pappalau | pappal001joh | 1903 | 4/30-7/16 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| John Pappalau | pappal001joh | 1903 | 7/24-7/27 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| John Pappalau | pappal001joh | 1903 | +8/15+ | Woonsocket RI | Independent | , | |
| John Pappalau | pappal001joh | 1903 | 9/3-9/25 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Al Pardee | pardee001alb | 1903 | 4/30-9/25 | Newark Sailors | Eastern League | , | |
| Harley Parker | parker001har | 1903 | where? | , | |||
| Jay Parker | parker002jay | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| Ross Parker | 1903 | Roseburg OR | Independent | , | |||
| Roy Parker | parker002roy | 1903 | U. of Illinois | College | , | ||
| Charles Parkins | parkin003cha | 1903 | 5/1-8/7 | Evansville River Rats | Central League | , | |
| J. Parkinson | parkin000j-- | 1903 | 9/8-9/11 | Meriden Silverites | Connecticut League | , | |
| Charles Parm | 1903 | 5/11-5/28 | Binghamton Bingoes | New York State League | , | ||
| Tom Parrott | parrot002tho | 1903 | 4/14-6/30 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Tom Parrott | parrot002tho | 1903 | 7/1-7/26 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Tom Parrott | parrot002tho | 1903 | 8/5-8/31 | Nashville Volunteers | Southern Association | , | |
| William Parsons | parson007wil | 1903 | 5/1-? | Lawrence Colts | New England League | , | |
| Parton | parton000--- | 1903 | 7/24 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Jim Partridge | partri001j-- | 1903 | +6/27-7/12 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Ladu Partridge | partri001lad | 1903 | 4/28-6/12 | Birmingham Barons | Southern Association | , | |
| Ladu Partridge | partri001lad | 1903 | Saugerties | Hudson River League | , | ||
| Ladu Partridge | partri001lad | 1903 | 8/24-9/20 | Albany Senators | New York State League | , | |
| William Partridge | partri001wil | 1903 | +6/30-8/11+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Bones Parvin | parvin001fra | 1903 | 5/9-6/10 | St. Joseph Saints | Western League | , | |
| Tony Pastor | pastor001hen | 1903 | 5/12-9/12 | Nashua | New England League | , | |
| Jim Pastorius | pastor002jam | 1903 | 5/10-9/19 | Albany Senators | New York State League | , | |
| John Patience | patien001joh | 1903 | 33 g. | Kingston Colonials | Hudson River League | , | |
| Harry Pattee | pattee001har | 1903 | Brown Univ. | College | , | ||
| Harry Pattee | pattee001har | 1903 | Newport NH | Independent | , | ||
| Patterson | 1903 | Richmond IN | Independent | , | |||
| Patterson | 1903 | 5/15-9/7 | Marion Oilworkers | Central League | , | ||
| Ham Patterson | patter001ham | 1903 | 5/7-5/28 | Omaha Indians | Western League | , | |
| Ham Patterson | patter001ham | 1903 | 6/5-8/1 | Denver Grizzlies | Western League | , | |
| J. Patterson | patter004j-- | 1903 | Salem | Willamette Valley | Salem, OR | ||
| J. Patterson | patter004j-- | 1903 | Portland-All Stars | Independent | , | ||
| Van Patterson | patter001van | 1903 | 5/8-6/11 | Ilion Typewriters | New York State League | , | |
| Van Patterson | patter001van | 1903 | 6/22- | Warren OH | Independent | , | |
| Will Pattison | pattis001w-- | 1903 | Dixon College | College | , | ||
| Will Pattison | pattis001w-- | 1903 | 101 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Owen Patton | patton001owe | 1903 | +6/4-6/9 | Umpire | Pacific National League | , | |
| August Paulig | paulig001aug | 1903 | 443 ab | Pine Bluff Lumbermen | Cotton States League | , | |
| August Paulig | paulig001aug | 1903 | Natchez Indians | Cotton States League | , | ||
| Fred Payne | payne-001fre | 1903 | 5/8-9/20 | Syracuse Stars | New York State League | , | |
| Joseph Payne | payne-001jos | 1903 | Decatur AL | Independent | , | ||
| Joseph Payne | payne-001jos | 1903 | +8/15-8/28+ | Huntsville | Tennessee-Alabama League | , | |
| Wood Payne | payne-008--- | 1903 | Bristol TN | Independent | , | ||
| Wood Payne | payne-008--- | 1903 | 8/31- | Knoxville TN | Independent | , | |
| John Peacock | peacoc002joh | 1903 | Hudson Marines | Hudson River League | , | ||
| Frank Pears | pears-002fra | 1903 | Alton IL | Independent | , | ||
| Frank Pears | pears-002fra | 1903 | 6/19-8/20 | MLB Umpire | American League | , | |
| Alex Pearson | pearso001ale | 1903 | 5/2-5/6 | Toronto Maple Leafs | Eastern League | , | |
| Alex Pearson | pearso001ale | 1903 | Homestead PA | Independent | , | ||
| Alex Pearson | pearso001ale | 1903 | -8/6 | 4 g. | Cleveland | American League | Cleveland, OH |
| George Pearson | 1903 | Sharon PA | Independent | , | |||
| Joseph Peartree | peartr001j-- | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Pease | 1903 | 6/29 | Nashville Volunteers | Southern Association | , | ||
| Charley Pease | pease-001cha | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Charley Pease | pease-001cha | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| Charley Pease | pease-001cha | 1903 | 5/7-6/14 | Atlanta Crackers | Southern Association | , | |
| Walter Pease | pease-001wal | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Walter Pease | pease-001wal | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| William Peeples | peeple001wil | 1903 | 4/14-8/16 | Helena Senators | Pacific National League | , | |
| Michael Peer | peer--001mic | 1903 | no g. | Cincinnati | National League | Cincinnati, OH | |
| Michael Peer | peer--001mic | 1903 | 4/26-5/17 | Milwaukee Brewers | American Association | , | |
| Michael Peer | peer--001mic | 1903 | 5/22-5/23 | Birmingham Barons | Southern Association | , | |
| Michael Peer | peer--001mic | 1903 | 6/24-8/26 | Fort Worth Panthers | Texas League | , | |
| Michael Peer | peer--001mic | 1903 | 8/31 | Buffalo Bisons | Eastern League | , | |
| Michael Peer | peer--001--- | 1903 | 9/25-9/26 | Providence Grays | Eastern League | , | |
| Heinie Peitz | peitz-001hen | 1903 | 105 g. | Cincinnati | National League | Cincinnati, OH | |
| Joseph Peloquin | peloqu001edm | 1903 | Holy Cross Univ. | College | , | ||
| Barney Pelty | pelty-001bar | 1903 | 39 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Barney Pelty | pelty-001bar | 1903 | St. Louis | American League | St. Louis, MO | ||
| Bob Pender | pender001rob | 1903 | 5/8-9/10 | Baton Rouge Red Sticks | Cotton States League | , | |
| Pendergraft | 1903 | 6/8-7/24 | Holdredge | Central Nebraska League | , | ||
| Ike Pendleton | pendle001isa | 1903 | 83 g. | Corsicana Oil Citys | Texas League | , | |
| Ike Pendleton | pendle001isa | 1903 | 8/27-8/31 | San Antonio Bronchos | South Texas League | , | |
| John Penland | 1903 | 4/30- | Pendleton | Inland Empire League | , | ||
| Art Pennell | pennel001art | 1903 | 5/9-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Art Pennell | pennel001art | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| George Pennington | pennin002geo | 1903 | 5/2-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| John Penquite | penqui000w-- | 1903 | +7/15+ | McCook | Central Nebraska League | , | |
| William Peoples | people001wil | 1903 | 75 g. | Kingston Colonials | Hudson River League | , | |
| Joseph Percival | perciv001jos | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Bob Perham | perham002w-- | 1903 | 4/14-5/22+ | San Francisco Pirates | Pacific National League | , | |
| Bob Perham | perham002w-- | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | ||
| Fred Perkins | perkin001fre | 1903 | Camden NJ | Independent | , | ||
| Ray Perkins | perkin001ray | 1903 | 5/11-9/12 | New Haven Blues | Connecticut League | , | |
| Tate Perkins | perkin013--- | 1903 | 4/25-5/12 | Galveston Sand Crabs | South Texas League | , | |
| Tate Perkins | perkin013--- | 1903 | 5/23-5/29 | Beaumont Oil Gushers | South Texas League | , | |
| Tate Perkins | perkin013--- | 1903 | 6/5-6/8 | Umpire | South Texas League | , | |
| Tate Perkins | perkin013--- | 1903 | 6/18-6/24 | Houston Buffaloes | South Texas League | , | |
| Tate Perkins | perkin013--- | 1903 | 7/8,8/15-8/16 | Umpire | South Texas League | , | |
| Blonde Perrin | 1903 | +6/15-7/11 | Selma YMCA | Alabama-Georgia League | , | ||
| Bull Perrine | perrin001fre | 1903 | Seattle Siwashes | Pacific Coast League | , | ||
| John Perrine | perrin002joh | 1903 | 5/2-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Perry | 1903 | 6/17-6/20+ | Crookston Crooks | Northern League | , | ||
| Perry | 1903 | +6/24-6/29+ | Superior Longshoremen | Northern League | , | ||
| Perry | 1903 | 7/31 | Grand Forks Forkers | Northern League | , | ||
| Red Perry | perry-001e-- | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Colly Persch | persch001col | 1903 | 6/16-6/23 | Leavenworth White Sox | Missouri Valley League | , | |
| Dutch Persch | persch001abn | 1903 | 5/2-7/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Dutch Persch | persch001abn | 1903 | 7/19-9/27 | Joplin Miners | Missouri Valley League | , | |
| Eddie Persons | person001edw | 1903 | 5/5-7/7 | Little Rock Travelers | Southern Association | , | |
| Eddie Persons | person001edw | 1903 | 56 ab | Baton Rouge Red Sticks | Cotton States League | , | |
| C. J. Peters | 1903 | Umpire | South Dakota | , | |||
| C. J. Peters | 1903 | 7/- | Umpire | Illinois-Indiana-Iowa League | , | ||
| Roscoe Petersen | 1903 | Atlantic | Southwest Iowa League | , | |||
| Peterson | peters024--- | 1903 | Oakland Heeseman | California State League | , | ||
| Peterson | peters076--- | 1903 | +6/12+ | Minden | Central Nebraska League | , | |
| Peterson | peters031--- | 1903 | Winnipeg Maroons | Northern League | , | ||
| Dave Peterson | 1903 | +7/29+ | Simpson KS | Independent | , | ||
| John Peterson | 1903 | 5/1- | Fall River Indians | New England League | , | ||
| John Peterson | 1903 | Brockton/New Bedford Whalers | New England League | Brockton, | |||
| John Peterson | 1903 | -5/19 | Lowell Tigers | New England League | , | ||
| Jim Pettigrew | pettig001jim | 1903 | Oklahoma City | , | |||
| Jim Pettigrew | pettig001jim | 1903 | Guthrie | , | |||
| Andrew Pettit | petit-001and | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| George Pfanmiller | pfanmi001geo | 1903 | 5/1-9/25 | Jersey City Skeeters | Eastern League | , | |
| Dan Pfenninger | pfenni001dan | 1903 | 5/8-9/16 | Umpire | New York State League | , | |
| Jack Pfiester | pfiest001joh | 1903 | 4/15-8/19 | San Francisco Pirates | Pacific National League | , | |
| Jack Pfiester | pfiest001joh | 1903 | 9/8 - | 3 g. | Pittsburgh | National League | Pittsburgh, PA |
| Pfister | pfiste000--- | 1903 | 8/19-9/1 | Terre Haute Hottentots | Central League | , | |
| Christ Pfrom | pfrom-001chr | 1903 | Allentown PA | Independent | , | ||
| George Phalen | phalen001geo | 1903 | Rochester | Catholic | , | ||
| George Phalen | phalen001geo | 1903 | Depew NY | Independent | , | ||
| George Phalen | phalen001geo | 1903 | 7/14-7/23 | Haverhill Hustlers | New England League | , | |
| George Phalen | phalen001geo | 1903 | Wellsville NY | Independent | , | ||
| Jack Phelan | phelan001jac | 1903 | 6/3-6/16 | Umpire | South Texas League | , | |
| Jack Phelan | phelan001jac | 1903 | 7/12-7/29,8/12 | Umpire | South Texas League | , | |
| Martin Phelan | phelan001mar | 1903 | Hudson Marines | Hudson River League | , | ||
| Ralph Philbrick | philbr001ral | 1903 | 5/10-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Phillips | 1903 | 9/7-9/11 | Pulaski | Al-n | , | ||
| Bill Phillips | philli005wil | 1903 | - 9/22 | 21 g. | Cincinnati | National League | Cincinnati, OH |
| E. C. Phillips | 1903 | Saugerties | Hudson River League | , | |||
| James Phillips | philli012jam | 1903 | no g. | Kansas City Cowboys | American Association | , | |
| James Phillips | philli012jam | 1903 | Pottsville PA | Independent | , | ||
| Harry Phipps | phipps001har | 1903 | 5/10-9/6 | Olympia Senators | Southwest Washington League | , | |
| Thomas Phoenix | phoeni001tho | 1903 | +7/12-8/22+ | Osceola | Southwest Iowa League | , | |
| Thomas Phoenix | phoeni001tho | 1903 | +7/16+ | Shenandoah | Southwest Iowa League | , | |
| Bill Phyle | phyle-002wil | 1903 | 4/22-6/26 | Milwaukee Brewers | American Association | , | |
| Bill Phyle | phyle-002wil | 1903 | 7/14-9/20 | Memphis Egyptians | Southern Association | , | |
| Wiley Piatt | piatt-001wil | 1903 | Boston | National League | Boston, MA | ||
| Wiley Piatt | piatt-001wil | 1903 | +8/15+ | Milford | Independent | , | |
| Wiley Piatt | piatt-001wil | 1903 | Lebanon NH | Independent | , | ||
| Pickard | pickar002--- | 1903 | 6/8-7/20+ | McCook | Central Nebraska League | , | |
| Ollie Pickering | picker001oli | 1903 | 137 g. | Philadelphia | American League | Philadelphia, PA | |
| Dave Pickett | picket003dav | 1903 | 4/30-9/16 | Marion Oilworkers | Central League | , | |
| Charles Piepho | piepho001c-- | 1903 | +5/10+ | Loui.-Frank Goss | Independent | , | |
| Charles Piepho | piepho001c-- | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Elmer Pierce | pierce001elm | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| Thurston Pierce | pierce001thu | 1903 | Oakland Heeseman | California State League | , | ||
| Pilscher | 1903 | 6/1-6/4 | Duluth Cardinals | Northern League | , | ||
| Pinckney | 1903 | Addison NY | Independent | , | |||
| J. G. Pinkerton | pinker000jg- | 1903 | +6/9 | Iola Gaslighters | Missouri Valley League | , | |
| Ed Pinnance | pinnan001edw | 1903 | Michigan State | College | , | ||
| Ed Pinnance | pinnan001edw | 1903 | Mt. Clemens MI | Independent | , | ||
| Ed Pinnance | pinnan001edw | 1903 | 9/14-9/29 | Philadelphia | American League | Philadelphia, PA | |
| Frank Piper | piper-001fra | 1903 | Decatur Commodores | Illinois-Indiana-Iowa League | , | ||
| Frank Piper | piper-001fra | 1903 | Kane PA | , | |||
| Frank Piper | piper-001fra | 1903 | Warren OH | , | |||
| Frank Piper | piper-001fra | 1903 | Homestead PA | Independent | , | ||
| George Piper | piper-000geo | 1903 | 5/1-5/5 | Dayton Veterans | Central League | , | |
| Pitcaithley | pitcai000--- | 1903 | 6/8- | Holdredge | Central Nebraska League | , | |
| Homer Plake | plake-001hom | 1903 | Ogden UT | Independent | , | ||
| Homer Plake | plake-001hom | 1903 | Atlantic | Southwest Iowa League | , | ||
| Homer Plake | plake-001hom | 1903 | 8/20-9/17 | St. Joseph Saints | Western League | , | |
| Ira Plank | plank-001ira | 1903 | 5/19-9/12 | Norwich Reds | Connecticut League | , | |
| Forrest Plass | plass-001for | 1903 | South Bend Greens | Central League | , | ||
| Forrest Plass | plass-001for | 1903 | Natchez Indians | Cotton States League | , | ||
| Eddie Pleiss | pleiss001edw | 1903 | 4/25-8/31 | Galveston Sand Crabs | South Texas League | , | |
| Plummer | plumme006--- | 1903 | Oakland Reliance | California State League | , | ||
| Plummer | plank-001ira | 1903 | OklahomaCityOKIndep | , | |||
| Plummer | plank-001ira | 1903 | 5/23-5/25 | Sedalia Goldbugs | Missouri Valley League | , | |
| Plummer | plumme012--- | 1903 | 6/9-6/15 | Leavenworth White Sox | Missouri Valley League | , | |
| George Pogson | pogson000geo | 1903 | 5/22,9/8-9/11 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Dee Poindexter | poinde001dee | 1903 | 4/25-8/26 | Fort Worth Panthers | Texas League | , | |
| Phillip Poland | poland002phi | 1903 | , | ||||
| Lou Polchow | polcho001lou | 1903 | 4/28-9/18 | Montgomery Black Sox | Southern Association | , | |
| George Pollis | 1903 | Newburgh Taylor-mades | Hudson River League | , | |||
| Pollock | 1903 | +7/16-10/12 | Camden NJ | Independent | , | ||
| Jack Pollock | polloc001joh | 1903 | 70 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Jack Pollock | polloc001joh | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Springf, | ||
| Jack Pollock | polloc001joh | 1903 | +7/16+ | Shenandoah | Southwest Iowa League | , | |
| Jack Pollock | polloc001joh | 1903 | +7/27+ | Osceola | Southwest Iowa League | , | |
| Polson | 1903 | , | |||||
| Clarence Poole | 1903 | Utica Pent-Ups | New York State League | , | |||
| Ed Poole | poole-001edw | 1903 | 25 g. | Cincinnati | National League | Cincinnati, OH | |
| Jap Poor | poor--001jas | 1903 | Wichita KS | Independent | , | ||
| Hoyt Poorman | poorma000hoy | 1903 | , | ||||
| Fred Popkay | popkay001fre | 1903 | 5/8-6/13 | Umpire | New York State League | , | |
| Fred Popkay | popkay001fre | 1903 | 6/15-7/13 | Binghamton Bingoes | New York State League | , | |
| Fred Popkay | popkay001fre | 1903 | 7/14-8/27 | Umpire | New York State League | , | |
| Bill Popp | popp--001wil | 1903 | 5/4-6/28 | Terre Haute Hottentots | Central League | , | |
| Ed Popp | popp--000ed- | 1903 | 7/9-7/18 | Terre Haute Hottentots | Central League | , | |
| Poppe | poppe-001--- | 1903 | +6/7+ | Musk.-Giants | Independent | , | |
| C.R. Porter | porter004c-- | 1903 | , | ||||
| Charles Porter | porter003c-- | 1903 | 5/2-7/6 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbC, | |
| Charles Porter | porter003c-- | 1903 | 7/7-9/13+ | Joplin Miners | Missouri Valley League | , | |
| T. M. Porter | porter003c-- | 1903 | 113 g. | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbC, | |
| T. M. Porter | porter003c-- | 1903 | Joplin Miners | Missouri Valley League | , | ||
| J. Frank Potts | potts-002j-- | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Bill Pounds | pounds001jea | 1903 | 5/2 | Cleveland | American League | Cleveland, OH | |
| Bill Pounds | pounds001jea | 1903 | 6/30 | Brooklyn | National League | Brooklyn, NY | |
| Bill Pounds | pounds001jea | 1903 | 7/4-8/30 | Baltimore Orioles | Eastern League | , | |
| Bill Pounds | pounds001jea | 1903 | Denver Grizzlies | Western League | , | ||
| Bill Pounds | pounds001jea | 1903 | Kingston Colonials | Hudson River League | , | ||
| Frank Powe | powe--000fra | 1903 | 6/12 | Anniston Invincibles | Alabama-Georgia League | , | |
| Abner Powell | powell001abn | 1903 | 4/27-9/20 | Atlanta Crackers | Southern Association | , | |
| Albert Powell | powell001b-- | 1903 | 7/24-9/27 | Joplin Miners | Missouri Valley League | , | |
| B. W. Powell | powell001b-- | 1903 | 20 g. | Joplin Miners | Missouri Valley League | , | |
| Jack Powell | powell007joh | 1903 | St. Louis | American League | St. Louis, MO | ||
| Powers | powers026--- | 1903 | 5/9-5/14 | Bridgeport Orators | Connecticut League | , | |
| Edward Powers | powers001edw | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| Edward Powers | powers001edw | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| J. A. Powers | 1903 | +4/3+ | U. Southern | College | , | ||
| Paul Pratt | pratt-001pau | 1903-05 | MT Sch of Mines | College | , | ||
| E. P. Preble | peble-001e-- | 1903 | President | Interstate League | , | ||
| Albert Pregont | pregon000alb | 1903 | Wausau WI | Independent | , | ||
| Del Pregont | pregon000del | 1903 | Wausau WI | Independent | , | ||
| Prentice | prenti005--- | 1903 | 6/11- | Red Cloud | Central Nebraska League | , | |
| Preston | 1903 | 8/3-8/10 | Haverhill Hustlers | New England League | , | ||
| Walt Preston | presto002wal | 1903 | 4/30-6/28 | Omaha Indians | Western League | , | |
| Walt Preston | presto002wal | 1903 | 7/1-9/17 | Peoria Distillers | Western League | , | |
| Howard Price | price-001how | 1903 | 5/2-6/39 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Ted Price | price-001e-- | 1903 | 4/30-9/16 | Wheeling Stogies | Central League | , | |
| Printz | 1903 | 54 g. | Iowa-South Dakota League | , | |||
| Billy Prout | prout-002wil | 1903 | 4/25-5/17 | Shreveport Giants | Southern Association | , | |
| Billy Prout | prout-002wil | 1903 | 5/18-6/21 | New Orleans Pelicans | Southern Association | , | |
| Billy Prout | prout-002wil | 1903 | 6/25-9/20 | Shreveport Giants | Southern Association | , | |
| Raymond Pulse | pulse-001ray | 1903 | 5/1-5/19 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Raymond Pulse | pulse-001ray | 1903 | +8/24+ | Fortville IN | Independent | , | |
| Nate Pulsifer | pulsif001nat | 1903 | 6/11-9/9 | Concord Marines | New England League | , | |
| Purcell | purcel014--- | 1903 | 6/4 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Frederick Purcell | purcel001the | 1903 | Lancaster OH | Independent | , | ||
| Frederick Purcell | purcel001the | 1903 | 4/18-5/15 | Helena Senators | Pacific National League | , | |
| Purceville | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Edward Purrington | purrin000edw | 1903 | 7/25 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Ambrose Puttmann | puttma001amb | 1903 | 4/15-8/16 | Helena Senators | Pacific National League | , | |
| Ambrose Puttmann | puttma001amb | 1903 | 8/22-8/26 | Spokane Indians | Pacific National League | , | |
| Ambrose Puttmann | puttma001amb | 1903 | 9/4- | 3 g. | New York | American League | New York, NY |
| William Pylant | pylant001w-- | 1903 | 8/11-8/19 | Pulaski | Tennessee-Alabama League | , | |
| William Pylant | pylant001w-- | 1903 | 8/21-9/7 | Columbia | Tennessee-Alabama League | , | |
| Jack Quan | quan--000tj- | 1903 | 5/11-6/3 | Binghamton Bingoes | New York State League | , | |
| Arthur Queisser | quisse001art | 1903 | +5/16+ | Wheeling Stogies | Central League | , | |
| Walter Queisser | queiss001wal | 1903 | +4/28+ | Indiana Law School | College | , | |
| Walter Queisser | queiss001wal | 1903 | +6/14+ | Indi.-Reserves | Independent | , | |
| Eddie Quick | quick-001edw | 1903 | 4/14-8/2+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland/SLC, | |
| Eddie Quick | quick-001edw | 1903 | 9/28 | New York | American League | New York, NY | |
| Arthur Quiesser | 1903 | no g. | Indianapolis Indians | American Association | , | ||
| Arthur Quiesser | 1903 | 5/10-5/20 | Anderson/Grand Rapids Orphans | Central League | Anderson, | ||
| Arthur Quiesser | 1903 | +6/14-9/23+ | Indi.-Reserves | Independent | , | ||
| Arthur Quiesser | 1903 | 7/26 | Evansville River Rats | Central League | , | ||
| Frank Quigg | quigg-001fra | 1903 | Umpire | Missouri Valley League | , | ||
| Ernest Quigley | quigle001ern | 1903-12 | St. Mary's College | College | , | ||
| Frank Quigley | quigle001fra | 1903 | 5/20-9/8 | Crookston Crooks | Northern League | , | |
| Lee Quillin | quille001leo | 1903 | 5/26-9/8 | Duluth Cardinals | Northern League | , | |
| Larry Quinlan | quinla001law | 1903 | 4/30-5/27 | Baltimore Orioles | Eastern League | , | |
| Larry Quinlan | quinla001law | 1903 | 6/6-9/20 | Louisville Colonels | American Association | , | |
| Quinn | quinn-005rob | 1903 | 7/26 | Columbus Senators | American Association | , | |
| Bobby Quinn | quinn-005rob | 1903 | 7/26 | Columbus Senators | American Association | , | |
| Frank Quinn | quinn-006fra | 1903 | 4/30-9/15 | Evansville River Rats | Central League | , | |
| Jack Quinn | quinn-004joh | 1903 | 5/8-6/9 | Binghamton Bingoes | New York State League | , | |
| Jack Quinn | quinn-004joh | 1903 | Elmira NY | Independent | , | ||
| Jack Quinn | quinn-007joh | 1903 | Connellsville | Pennsylvania State League | , | ||
| Jimmy Quinn | quinn-000jim | 1903 | Hudson Marines | Hudson River League | , | ||
| Joe Quinn | quinn-003jos | 1903 | 4/28-9/17 | Des Moines Undertakers | Western League | , | |
| M. Quinn | quinn-000jim | 1903 | Hudson Marines | Hudson River League | , | ||
| Tad Quinn | quinn-001cla | 1903 | Philadelphia | American League | Philadelphia, PA | ||
| Tad Quinn | quinn-001cla | 1903 | 5/26-9/12 | Norwich Reds | Connecticut League | , | |
| Thomas Quinn | quinn-001tho | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Fred Quitman | quitma001fra | 1903 | preseason | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Fred Quitman | quitma001fra | 1903 | +6/21+ | Chic.-Edgars | Independent | , | |
| Fred Quitman | quitma001fra | 1903 | 7/24-8/31 | Houston Buffaloes | South Texas League | , | |
| Teddy Radcliffe | radcli001c-- | 1903 | 5/3-6/15 | Denver Grizzlies | Western League | , | |
| Teddy Radcliffe | radcli001c-- | 1903 | 6/28-7/9 | Colorado Springs Millionaires | Western League | , | |
| Teddy Radcliffe | radcli001c-- | 1903 | 7/10-8/30 | Denver Grizzlies | Western League | , | |
| J. Radford | radfor001j-- | 1903 | Petaluma | California State League | , | ||
| J. Radford | radfor001j-- | 1903 | Oakland Heeseman | California State League | , | ||
| Raferty | 1903 | Amherst | College | , | |||
| Raferty | 1903 | Greenfield MA | Independent | , | |||
| Jack Rafter | rafter001joh | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Tom Raftery | rafter001tho | 1903 | 9/2 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Arthur Ragan | reagan001art | 1903 | 4/29-8/25 | Dallas Giants | Texas League | , | |
| Arthur Ragan | reagan001art | 1903 | 5/22-6/8 | Beaumont Oil Gushers | South Texas League | , | |
| Arthur Ragan | reagan001art | 1903 | 9/19-9/27 | Cincinnati | National League | Cincinnati, OH | |
| Benjamin Ragsdale | ragsda001ben | 1903 | +6/23+ | Durant IT | Independent | , | |
| Joe Raidy | raidy-001jos | 1903 | 98 g. | Portland Browns | Pacific Coast League | , | |
| Thomas Railing | railin001tho | 1903 | 4/26-8/24 | Dallas Giants | Texas League | , | |
| Rainey | 1903 | 5/10 | Montgomery Black Sox | Southern Association | , | ||
| Edward Rainey | rainey001e-- | 1903 | 5/10-9/10 | Troy Trojans | New York State League | , | |
| Ralph | ralph-000--- | 1903 | +7/15-7/22+ | Red Cloud | Central Nebraska League | , | |
| Ralph | 1903 | 9/1 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | ||
| William Ramage | 1903 | Ossining/Catskill | Hudson River League | Ossining, | |||
| John Ramey | ramey-002joh | 1903 | Pueblo- C. F. I. | Independent | , | ||
| Ramio | 1903 | 5/23 | Albany Senators | New York State League | , | ||
| Mark Ramp | 1903 | 11 g. | Montgomery Black Sox | Interstate League | , | ||
| George Ramsey | ramsey001geo | 1903 | Green Bay WI | Independent | , | ||
| Hank Ramsey | ramsey001hen | 1903 | 5/23-9/27 | Kingston Colonials | Hudson River League | , | |
| Ranberger | ranber000--- | 1903 | 7/9-7/13 | Terre Haute Hottentots | Central League | , | |
| Newt Randall | randal001new | 1903 | 5/20-9/8 | Winnipeg Maroons | Northern League | , | |
| Randolph | 1903 | 5/13-5/15 | Nashua | New England League | , | ||
| Randolph | randol003--- | 1903 | 5/31-6/3 | Wheeling Stogies | Central League | , | |
| C. R. Rankin | 1903 | 7 g. | Brewton | Interstate League | , | ||
| Guy Rankin | 1903 | Fort Dodge | Iowa League | , | |||
| J. Rankin | rankin001j-- | 1903 | +6/1+ | Portl.-All Stars | Independent | , | |
| Edward Ransick | ransic001edw | 1903 | Charleston WV | Independent | , | ||
| Frederick Ransome | ransom001fra | 1903 | 16 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Frederick Ransome | ransom001fra | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| Phil Ranz | ranz--000--- | 1903 | 6/2-6/8 | Terre Haute Hottentots | Central League | , | |
| Charles Rapp | rapp--001cha | 1903 | 7/14-7/24 | Dayton Veterans | Central League | , | |
| Louis Rapp | rapp--001lou | 1903 | 5/1-9/12 | Manchester | New England League | , | |
| Louis Rapp | rapp--001lou | 1903 | 9/18-9/26 | Toronto Maple Leafs | Eastern League | , | |
| William Rapps | rapps-001wil | 1903 | 5/2-6/30+ | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| William Rapps | rapps-001wil | 1903 | 7/8-9/27 | Joplin Miners | Missouri Valley League | , | |
| Rathbun | rathbu001--- | 1903 | Ionia MI | Independent | , | ||
| John Raub | raub--001--- | 1903 | 5/10-8/9 | Centralia Midgets | Southwest Washington League | , | |
| Tommy Raub | raub--001tho | 1903 | 5/3- | 36 g. | Chicago | National League | Chicago, IL |
| Thomas Ray | ray---002tho | 1903 | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | ||
| Thomas Rayburn | raybur001--- | 1903 | 7/17-8/17 | Corsicana Oil Citys | Texas League | , | |
| Fred Raymer | raymer001fre | 1903 | 4/22-9/8 | Columbus Senators | American Association | , | |
| Bugs Raymond | raymon001art | 1903 | Appleton WI | Independent | , | ||
| Charles Raymond | raymon008--- | 1903 | 5/21-6/20 | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Charles Raymond | raymon008--- | 1903 | 6/24-8/7+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Tealey Raymond | raymon002fra | 1903 | Oakland Reliance | California State League | , | ||
| Tealey Raymond | raymon002fra | 1903 | 37 g. | Los Angeles Angels | Pacific Coast League | , | |
| Tealey Raymond | raymon002fra | 1903 | 27 g. | San Francisco Seals | Pacific Coast League | , | |
| Rea | rea---000--- | 1903 | +5/24+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | |
| Rea | rea---000--- | 1903 | 7/5 | Sioux City Soos | Iowa-South Dakota League | , | |
| Charles Reading | readin001cha | 1903 | 90 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Charles Reading | readin001cha | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| George Ream | ream--001geo | 1903 | 4/30-9/11 | South Bend Greens | Central League | , | |
| John Rebsamen | rebsam001joh | 1903 | 50 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| William Rebscher | rebsch001wil | 1903 | Kewanee IL | Independent | , | ||
| Wallace Reddick | reddic001wal | 1903 | +6/28+ | Mt. Pleasant MI | Independent | , | |
| Redman | redman002--- | 1903 | 7/25-8/11 | Fort Scott Giants | Missouri Valley League | , | |
| Redman | redman002--- | 1903 | Univ. of Illinois | College | , | ||
| James Redmond | redmon003jam | 1903 | 5/18-7/16 | Leavenworth White Sox | Missouri Valley League | , | |
| James Redmond | redmon003jam | 1903 | 7/21-9/17 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Reed | reed--026--- | 1903 | San Jose | California State League | , | ||
| Ed Reed | reed--004ed- | 1903 | 7/4 | McCook | Central Nebraska League | , | |
| Edward Reed | reed--001edw | 1903 | 5/1-5/16 | South Bend Greens | Central League | , | |
| Edward Reed | reed--001edw | 1903 | 7/1-9/14 | Terre Haute Hottentots | Central League | , | |
| George Reed | reed--003geo | 1903 | 4/14-4/25+ | Spokane Indians | Pacific National League | , | |
| Ray Reed | reed--002ray | 1903 | +5/14-6/14 | Colfax | Inland Empire League | , | |
| Thomas Reed | reed--001tho | 1903 | 5/28-7/10+8/28 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Zeke Reed | reed--000zek | 1903 | Helena MT | Independent | , | ||
| Ralph Reeve | 1903 | Dartmouth Col | College | , | |||
| Ralph Reeve | 1903 | Somersworth NH | Independent | , | |||
| Reeves | reeves010--- | 1903 | 9/4 | Pulaski | Tennessee-Alabama League | , | |
| Reeves | reeves009--- | 1903 | 5/10 | Sedalia Goldbugs | Missouri Valley League | , | |
| Billy Reeves | reeves001wil | 1903 | 17 g. | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Bill Reid | reid--002wil | 1903 | Warren OH | Independent | , | ||
| Robert Reid | reid--001r-- | 1903 | 5/2-5/28 | Sedalia Goldbugs | Missouri Valley League | , | |
| Robert Reid | reid--001r-- | 1903 | 6/15- | Humboldt NE | Independent | , | |
| Bill Reidy | reidy-001wil | 1903 | 5 g. | St. Louis | American League | St. Louis, MO | |
| Bill Reidy | reidy-001wil | 1903 | 15 g. | Brooklyn | National League | Brooklyn, NY | |
| Thomas Reilley | reille000tho | 1903 | 6/22-6/26 | Hartford Senators | Connecticut League | , | |
| Charlie Reilly | reilly003cha | 1903 | 4/14-8/19 | Los Angeles | Pacific National League | , | |
| Josh Reilly | reilly002wil | 1903 | 7 g. | Sacramento Senators | Pacific Coast League | , | |
| Josh Reilly | reilly002wil | 1903 | 12 g. | Portland Browns | Pacific Coast League | , | |
| Josh Reilly | reilly002wil | 1903 | 27 g. | Oakland Oaks | Pacific Coast League | , | |
| Josh Reilly | reilly002wil | 1903 | San Jose | California State League | , | ||
| Tom Reilly | reilly004tho | 1903 | Hartford Senators | Connecticut League | , | ||
| Phil Reisinger | reisin001phi | 1903 | Greenville Grays | Cotton States League | , | ||
| Doc Reisling | reisli001fra | 1903 | 4/22-9/20 | Toledo Mud Hens | American Association | , | |
| George Reitz | reitz-001geo | 1903 | 4/26- | Dallas Giants | Texas League | , | |
| George Reitz | reitz-001geo | 1903 | -8/26 | Fort Worth Panthers | Texas League | , | |
| Henry Reitz | reitz-001hen | 1903 | Vallejo CA | , | |||
| Henry Reitz | reitz-001hen | 1903 | Fortuna CA | Independent | , | ||
| Henry Reitz | reitz-001hen | 1903 | Petaluma | California State League | , | ||
| Clarence Relf | reid--001r-- | 1903 | 288 ab | Baton Rouge Red Sticks | Cotton States League | , | |
| Clarence Relf | relf--001cha | 1903 | Greenville Grays | Cotton States League | , | ||
| Art Relihan | reliha001art | 1903 | 5/3-6/29 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Butch Rementer | rement001wil | 1903 | Camden NJ | Independent | , | ||
| James Renwick | renwic001jam | 1903 | Calumet | , | |||
| Ed Reulbach | reulba001edw | 1903 | Notre Dame Univ | College | , | ||
| Ed Reulbach | reulba001edw | 1903 | 6/9-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Sam Reust | reust-001sam | 1903 | Joplin Miners | Missouri Valley League | , | ||
| Sam Reust | reust-001sam | 1903 | +9/10+ | Frankfort KS | Independent | , | |
| H. W. Reynolds | 1903 | Monroe Hill Citys | Cotton States League | , | |||
| Jesse Reynolds | reynol001jes | 1903 | 5/4-6/2 | Manchester | New England League | , | |
| Jesse Reynolds | reynol001jes | 1903 | Natchez Indians | Cotton States League | , | ||
| John Reynolds | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |||
| Tommy Reynolds | reynol001tho | 1903 | 5/20-6/3 | Fargo | Northern League | , | |
| Rhea | rhea--003--- | 1903 | 6/8- | Holdredge | Central Nebraska League | , | |
| Rhea | rhea--003--- | 1903 | +6/15-7/2+ | Red Cloud | Central Nebraska League | , | |
| Bob Rhoads | rhoads001rob | 1903 | Cleveland | American League | Cleveland, OH | ||
| Edgar Rhodes | rhodes004dus | 1903 | 6/8-7/24 | McCook | Central Nebraska League | , | |
| Frank Rhoton | rhoton001fra | 1903 | +5/19+ | Knoxville TN | Independent | , | |
| William Riccius | ricciu001wil | 1903 | 5/1-9/12 | Fall River Indians | New England League | , | |
| Arthur Rice | rice--001art | 1903 | 91 g. | Kingston Colonials | Hudson River League | , | |
| Laurence Rice | rice--001law | 1903-07 | Cornell Univ. | College | , | ||
| Laurence Rice | rice--001law | 1903 | Elmira-FatherMathew | Independent | , | ||
| Lew Rice | rice--018--- | 1903 | San Francisco | California State League | , | ||
| Lew Rice | rice--018--- | 1903 | Oakland Heeseman | California State League | , | ||
| Bill Richardson | richar006wil | 1903 | 4/30-9/16 | Terre Haute Hottentots | Central League | , | |
| Forrest Richardson | richar001w-- | 1903 | 5/1-9/12 | Haverhill Hustlers | New England League | , | |
| Joe Rickert | ricker001jos | 1903 | 4/30-6/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Joe Rickert | ricker001jos | 1903 | 6/22-9/4 | New Orleans Pelicans | Southern Association | , | |
| Branch Rickey | rickey001wes | 1903 | 6/19 | Terre Haute Hottentots | Central League | , | |
| Branch Rickey | rickey001wes | 1903 | +6/29-7/25+ | Le Mars Blackbirds | Iowa-South Dakota League | , | |
| Orla Rickey | rickey000ed- | 1903 | 6/19 | Terre Haute Hottentots | Central League | , | |
| Dorsey Riddlemoser | riddle002dor | 1903 | 5/11 | Meriden Silverites | Connecticut League | , | |
| Charles Rigler | rigler001cy- | 1903 | , | ||||
| James Riley | riley-010jam | 1903 | 7/7 | Haverhill Hustlers | New England League | , | |
| Frank Rinn | rinn--002fra | 1903 | 8/31- | Umpire | Independent | , | |
| Jimmy Riordan | 1903 | Christian Bros. | College | , | |||
| Jimmy Riordan | 1903 | Alton IL | Independent | , | |||
| John Riordan | riorda001joh | 1903 | 5/8-6/25 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| John Riordan | riorda001joh | 1903 | 6/26-7/11 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Pop Rising | rising001per | 1903 | 5/7-9/10 | New London Whalers | Connecticut League | , | |
| Dud Risley | risley001dud | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Harvey Ritter | ritter002har | 1903 | Brandywine PA | Independent | , | ||
| Lew Ritter | ritter002lew | 1903 | Brooklyn | National League | Brooklyn, NY | ||
| John Roach | roach-003joh | 1903 | , | ||||
| Mike Roach | roach-001mik | 1903 | 4/23-9/20 | Columbus Senators | American Association | , | |
| Skel Roach | roach-001rud | 1903 | U. Michigan | College | , | ||
| Skel Roach | roach-001rud | 1903 | 6/6-10/4 | Butte Miners | Pacific National League | , | |
| Charles Roadnight | roadni000cha | 1903 | +9/6+ | Spokane AC | Independent | , | |
| Clay Robb | robb--001cla | 1903 | 8/9-8/29 | Beaumont Oil Gushers | South Texas League | , | |
| Clay Robb | robb--001cla | 1903 | 8/31 | San Antonio Bronchos | South Texas League | , | |
| Craig Robbins | robbin000smi | 1903 | +6/22-7/9 | Selma YMCA | Alabama-Georgia League | , | |
| Vince Robbins | robbin001vin | 1903 | +6/14+ | FW-Shamrocks | Independent | , | |
| Vince Robbins | robbin001vin | 1903 | 6/28-7/12 | Fort Wayne Railroaders | Central League | , | |
| Roberts | robert041--- | 1903 | 29 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Harry Roberts | robert003har | 1903 | 4/3- | U. Alabama | College | , | |
| Harry Roberts | robert003har | 1903 | 6/12-7/28 | Talladega Tigers | Alabama-Georgia League | , | |
| Harry Roberts | robert003har | 1903 | +8/14+ | Gadsden AL | Independent | , | |
| John Robertshaw | robert014joh | 1903 | no g. | Milwaukee Creams | Western League | , | |
| Robertson | robert054--- | 1903 | 28 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| William Robertson | robert009wil | 1903 | Piqua OH | Independent | , | ||
| Robinson | robins050--- | 1903 | 4/30-5/5 | South Bend Greens | Central League | , | |
| Robinson | robins050--- | 1903 | 5/12-6/1 | Terre Haute Hottentots | Central League | , | |
| Robinson | robins061--- | 1903 | 7/29-7/31 | Hartford Senators | Connecticut League | , | |
| Robinson | robins024--- | 1903 | 8/18-8/22 | Fort Worth Panthers | Texas League | , | |
| Robinson | robins070--- | 1903 | Roseburg | Willamette Valley | Roseburg, OR | ||
| John Robinson | 1903 | 8/12-8/19 | Umpire | Southern Association | , | ||
| R. Robinson | robins000r-- | 1903 | 5/2-5/28 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Rabbit Robinson | robins003wil | 1903 | Washington | American League | Washington, DC | ||
| Wilbert Robinson | robins001wil | 1903 | 4/30-9/12 | Baltimore Orioles | Eastern League | , | |
| Chick Robitaille | robita001jos | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Roche | 1903 | +5/230 | Walla Walla | Inland Empire League | , | ||
| Cornelius Roche | 1903 | 5/1-5/20 | Houston Buffaloes | South Texas League | , | ||
| Mike Rochford | rochfo001mic | 1903 | 5/1-5/9 | Haverhill Hustlers | New England League | , | |
| Mike Rochford | rochfo001mic | 1903 | 6/23-8/22 | New London Whalers | Connecticut League | , | |
| Mike Rochford | rochfo001mic | 1903 | 8/27-9/10 | Hartford Senators | Connecticut League | , | |
| Arthur Rochon | robert041--- | 1903 | 5/10-6/14 | Centralia Midgets | Southwest Washington League | , | |
| Arthur Rochon | rochon001w-- | 1903 | 6/21 | Olympia Senators | Southwest Washington League | , | |
| Walter Rochon | rochon000wal | 1903 | 5/10+ | Centralia Midgets | Southwest Washington League | , | |
| Walter Rochon | rochon000wal | 1903 | Olympia Senators | Southwest Washington League | , | ||
| Roy Rock | rock--002roy | 1903 | Manhattan Col. | College | , | ||
| Roy Rock | rock--002roy | 1903 | 8/3-9/26 | Providence Grays | Eastern League | , | |
| Ike Rockenfield | rocken001isa | 1903 | 19 g. | Oakland Oaks | Pacific Coast League | , | |
| Ike Rockenfield | rocken001isa | 1903 | 4/14-8/16 | Tacoma Tigers | Pacific National League | , | |
| Ike Rockenfield | rocken001isa | 1903 | 8/23 | Olympia Senators | Southwest Washington League | , | |
| Ike Rockenfield | rocken001isa | 1903 | +9/23-10/4 | Seattle Chinooks | Pacific National League | , | |
| Rockford | rockfo001--- | 1903 | Petaluma | California State League | , | ||
| Ernest Roder | roder-001ern | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Chester Rodgers | rodger001che | 1903 | San Francisco | California State League | , | ||
| Roe | roe---002--- | 1903 | Dartmouth Col | College | , | ||
| Roe | roe---002--- | 1903 | Littleton NH | Independent | , | ||
| Billy Roedel | roedel001wil | 1903 | 5/2-9/27 | Joplin Miners | Missouri Valley League | , | |
| Fred Rogers | rogers002fra | 1903 | 5/20-9/8 | Winnipeg Maroons | Northern League | , | |
| Terry Rogers | rogers001ter | 1903 | 5/7-7/9 | Norwich Reds | Connecticut League | , | |
| William Rogers | rogers001wil | 1903 | 5/7-9/9 | Meriden Silverites | Connecticut League | , | |
| William Rogers | 1903 | Corsicana Oil Citys | Texas League | , | |||
| George Rohe | rohe--001geo | 1903 | 4/28-9/17 | St. Joseph Saints | Western League | , | |
| Dick Rohn | rohn--001ric | 1903 | 5/2-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Dillwyn Rollins | rollin001j-- | 1903 | 5/26 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Romer | 1903 | Areata | Humboldt | , | |||
| Jerry Ronesch | ronesc001jer | 1903 | +8/3+ | Miles City MT | , | ||
| John Root | root--001joh | 1903 | 5/3-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Roper | roper-006--- | 1903 | 6/1-6/2 | New London Whalers | Connecticut League | , | |
| Charles Rose | rose--004cha | 1903 | 5/20-9/8 | Fargo | Northern League | , | |
| Charles Rose | rose--004cha | 1903 | U. ND Agricultural | College | , | ||
| Ross | ross--034--- | 1903 | 8/23 | Evansville River Rats | Central League | , | |
| Art Ross | ross--001art | 1903 | 198 g. | Los Angeles Angels | Pacific Coast League | , | |
| Ernie Ross | ross--001ern | 1903 | no g. | Concord Marines | New England League | , | |
| Ernie Ross | ross--001ern | 1903 | 5/5- | Lawrence Colts | New England League | , | |
| Ernie Ross | ross--001ern | 1903 | -7/16 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| Ernie Ross | ross--001ern | 1903 | 7/23-8/1 | Rochester Bronchos | Eastern League | , | |
| Frank Ross | 1903 | Ogden UT | Independent | , | |||
| W. L.? Ross | 1903 | Springfield Midgets | Missouri Valley League | , | |||
| Claude Rossman | rossma001cla | 1903 | 5/8-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Lester Rosson | rosson001les | 1903 | 4/30-9/16 | Wheeling Stogies | Central League | , | |
| Roth | 1903 | 5/15 | St. Joseph Saints | Western League | , | ||
| Andy Roth | roth--001and | 1903 | 5/7-5/9 | Nashville Volunteers | Southern Association | , | |
| Andy Roth | roth--001and | 1903 | 5/19-9/20 | Nashville Volunteers | Southern Association | , | |
| Frank Roth | roth--001fra | 1903 | 4/18- | 68 g. | Philadelphia | National League | Philadelphia, PA |
| Bobby Rothermel | rother001bob | 1903 | 435 ab | Baton Rouge Red Sticks | Cotton States League | , | |
| C. Rothermel | rother002--- | 1903 | +9/13+ | Minersville PA | Independent | , | |
| Jack Rothfuss | rothfu001jac | 1903 | 4/22-9/21 | Kansas City Cowboys | American Association | , | |
| Billy Rourke | rourke001wil | 1903 | 4/28-9/17 | Omaha Indians | Western League | , | |
| Dave Rowan | rowan-001dav | 1903 | 5/10-5/28 | Syracuse Stars | New York State League | , | |
| Dave Rowan | rowan-001dav | 1903 | Corning NY | Independent | , | ||
| Dave Rowan | rowan-001dav | 1903 | Seattle | , | |||
| Rowe | rowe--015--- | 1903 | 4/6- | Davidson College | College | , | |
| Rowe | rowe--015--- | 1903 | +6/12+ | Winston NC | Independent | , | |
| Rowen | rowen-000--- | 1903 | 6/10-6/17 | Hartford Senators | Connecticut League | , | |
| Clarence Rowland | rowlan001pan | 1903 | 5/1-6/30 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| A.B. Royce | royce-001a-- | 1903 | , | ||||
| Ted Ruark | 1903 | Monroe Hill Citys | Cotton States League | , | |||
| Jesse Ruby | ruby--001jes | 1903 | Purdue Univ | College | , | ||
| Jesse Ruby | ruby--001jes | 1903 | 102 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Orlando Rudd | rudd--001o-- | 1903 | 96 g. | Natchez Indians | Cotton States League | , | |
| Frank Rudderham | rudder001fra | 1903 | 5/30-9/18 | Albany Senators | New York State League | , | |
| John Rudderham | rudder001joh | 1903 | 5/1-6/2;7/25-31 | Umpire | New England League | , | |
| John Rudolph | rudolp001joh | 1903 | Homestead PA | Independent | , | ||
| John Rudolph | rudolp001joh | 1903 | 7/3 | Philadelphia | National League | Philadelphia, PA | |
| Fred Ruehr | ruehr-001--- | 1903 | 5/1-5/26 | Atlanta Crackers | Southern Association | , | |
| Fred Ruehr | ruehr-001--- | 1903 | +7/4+ | Jacksonville FL | Independent | , | |
| Paul Ruff | ruff--001pau | 1903 | 5/10-9/6 | Centralia Midgets | Southwest Washington League | , | |
| Harry Ruh | ruh---001har | 1903 | Greensburg Reds | , | |||
| Gus Ruhland | ruhlan001gus | 1903 | Tampa FL | Independent | , | ||
| Lee Rundell | rundel001g-- | 1903 | 4/25-5/3 | Corsicana Oil Citys | Texas League | , | |
| Lee Rundell | rundel001g-- | 1903 | 5/10-6/1 | Galveston Sand Crabs | South Texas League | , | |
| Lee Rundell | rundel001g-- | 1903 | +6/19+ | Cawthons TX | Independent | , | |
| Lee Rundell | rundel001g-- | 1903 | 7/12 | Beaumont Oil Gushers | South Texas League | , | |
| Louis Runkel | runkle001lou | 1903 | 4/28-5/14 | Peoria Distillers | Western League | , | |
| Louis Runkel | runkle001lou | 1903 | +6/26-10/4 | Butte Miners | Pacific National League | , | |
| Clyde Rupert | rupert000red | 1903 | Albany | Willamette Valley | Albany, OR | ||
| A. C. Ruphel | 1903 | 4/30-5/22+ | Colfax | Inland Empire League | , | ||
| Rush | rush--006--- | 1903 | +7/20-7/22+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| H. Rush | 1903 | 4 g. | Mobile | Interstate League | , | ||
| George Rushworth | rushwo000geo | 1903 | 5/7 | New London Whalers | Connecticut League | , | |
| Amos Rusie | rusie-001amo | 1903 | Vincennes Alices | Kentucky-Illinois-Tennessee League | , | ||
| Amos Rusie | rusie-001amo | 1903 | Vincennes IN | Independent | , | ||
| Burt Russell | russel000bur | 1903 | Seattle | , | |||
| Clyde Russell | russel001cly | 1903 | 5/6-9/20 | Nashville Volunteers | Southern Association | , | |
| Cy Russell | russel002fra | 1903 | Oakland Heeseman | California State League | , | ||
| Cy Russell | russel002fra | 1903 | 1 g. | Sacramento Senators | Pacific Coast League | , | |
| John Russell | russel006jac | 1903 | 6/2-9/15 | Evansville River Rats | Central League | , | |
| Walter Russell | 1903 | Homestead PA | Independent | , | |||
| Joseph Rutherford | ruther001jos | 1903 | Steelton PA YMCA | Independent | , | ||
| Joseph Rutherford | ruther001jos | 1903 | Maritta PA | Independent | , | ||
| Joseph Rutherford | ruther001jos | 1903 | 9/4-9/26 | Baltimore Orioles | Eastern League | , | |
| Lou Rutledge | rutled001lou | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | ||
| Lou Rutledge | rutled001lou | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Ryan | ryan--070--- | 1903 | 5/9-5/15 | Hartford Senators | Connecticut League | , | |
| Ryan | 1903 | Tacoma Tigers | California State League | , | |||
| Jack Ryan | ryan--004joh | 1903 | 67 g. | St. Louis | National League | St. Louis, MO | |
| James Ryan | 1903 | 8/17-9/11 | Umpire | New England League | , | ||
| Jimmy Ryan | ryan--003jam | 1903 | -9/24 | 114 g. | Washington | American League | Washington, DC |
| Raymond Ryan | ryan--001ray | 1903 | Greensburg IN | Independent | , | ||
| William Ryan | ryan--006wil | 1903 | Greenville Grays | Cotton States League | , | ||
| William Ryan | ryan--006wil | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Rydeen | rydeen001--- | 1903 | +7/18-7/25+ | Winnipeg Maroons | Northern League | , | |
| Edwin Sabrie | sabrie001edw | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| James Sager | sager-001jam | 1903 | 5/1 | Concord Marines | New England League | , | |
| James Sager | sager-001jam | 1903 | 5/18-9/16 | South Bend Greens | Central League | , | |
| Harry Saillard | sailla001har | 1903 | +8/15-9/5+ | Huntsville | Tennessee-Alabama League | , | |
| Solly Salisbury | salisb001wil | 1903 | 5/25-5/30 | Minneapolis Millers | American Association | , | |
| Walter Salm | salm--001wal | 1903 | Wapakoneta OH | Independent | , | ||
| Walter Salm | salm--001wal | 1903 | Finley OH | Independent | , | ||
| Salter | salter003--- | 1903 | 5/8-5/11 | Rochester Bronchos | Eastern League | , | |
| Guy Sample | sample001guy | 1903 | 64 ab | Pine Bluff Lumbermen | Cotton States League | , | |
| Guy Sample | sample001guy | 1903 | 44 g. | Seattle Siwashes | Pacific Coast League | , | |
| Sanchez | sanche004--- | 1903 | 3 g. | Brewton | Interstate League | , | |
| Sanchez | sanche004--- | 1903 | Montgomery Black Sox | Interstate League | , | ||
| Reuben Sanders | sander000rub | 1903 | 5/9-7/27+ | Salem | Willamette Valley | Salem, OR | |
| War Sanders | sander001war | 1903 | 4/18- | 8 g. | St. Louis | National League | St. Louis, MO |
| War Sanders | sander001war | 1903 | 7/9-9/12 | Omaha Indians | Western League | , | |
| Sanderson | sander026--- | 1903 | +6/13+ | Minden | Central Nebraska League | , | |
| Nelson Sandherr | sandhe001nel | 1903 | 5/31 | Baltimore Orioles | Eastern League | , | |
| Nelson Sandherr | sandhe001nel | 1903 | +8/18+ | Williamsport PA | Independent | , | |
| Sanford | sanfor012--- | 1903 | 7/4 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| William Sanford | sanfor000wil | 1903 | 6/16-8/8+ | Anniston Invincibles | Alabama-Georgia League | , | |
| Andy Santleben | santla001--- | 1903 | 5/17-5/20 | San Antonio Bronchos | South Texas League | , | |
| Sapp | sapp--001--- | 1903 | +5/19-6/1+ | Wilmington DE | Independent | , | |
| William Sarsfield | sarsfi002--- | 1903 | +8/13+ | Hornellsville NY | Independent | , | |
| Waldo Sasse | sasse-003--- | 1903 | Kane PA | Independent | , | ||
| Saunders | 1903 | Tufts | College | , | |||
| Saunders | 1903 | Littleton NH | Independent | , | |||
| Sheep Sawyer | sawyer010--- | 1903 | Decatur AL | Independent | , | ||
| Sheep Sawyer | sawyer010--- | 1903 | +8/19-9/1+ | Pulaski | Tennessee-Alabama League | , | |
| James Sayer | sayer-001jam | 1903 | 5/8-8/? | Utica Pent-Ups | New York State League | , | |
| Del Sayers | sayers001del | 1903 | 6/19-6/24 | Terre Haute Hottentots | Central League | , | |
| Doc Scanlan | scanla001wil | 1903 | Syracuse Univ. | College | , | ||
| Doc Scanlan | scanla001wil | 1903 | 5/9-9/20 | Ilion Typewriters | New York State League | , | |
| Doc Scanlan | scanla001wil | 1903 | 9/24 | Pittsburgh | National League | Pittsburgh, PA | |
| Jack Scanlon | scanla001joh | 1903 | 5/8-5/12 | Holyoke Paperweights | Connecticut League | , | |
| Scanlon? Scannel | scanne000--- | 1903 | 5/2 | South Bend Greens | Central League | , | |
| George Schaefer | schaef002geo | 1903 | 4/30-9/14 | South Bend Greens | Central League | , | |
| Germany Schaefer | schaef001her | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| Schafer | schafe007--- | 1903 | 6/2-6/3 | Terre Haute Hottentots | Central League | , | |
| Ben Schafstall | schafs001ber | 1903 | 5/3-9/13 | Omaha Indians | Western League | , | |
| Henry Scharnweber | scharn001hen | 1903 | 5/20-9/8 | Grand Forks Forkers | Northern League | , | |
| Fred Schatzke | schatz001fre | 1903 | 5/12-8/26 | Fort Worth Panthers | Texas League | , | |
| Schaub | schaub006--- | 1903 | +7/14+ | Red Cloud | Central Nebraska League | , | |
| Schaub | schaub006--- | 1903 | +6/28-7/24 | Holdredge | Central Nebraska League | , | |
| Bob Schaub | schaub001rob | 1903 | 4/26-5/24 | Louisville Colonels | American Association | , | |
| Bob Schaub | schaub001rob | 1903 | 5/30-9/20 | Toledo Mud Hens | American Association | , | |
| Louis Schaub | schaub001lou | 1903 | 7/ | Fort Dodge IA | Independent | , | |
| Louis Schaub | schaub001lou | 1903 | +9/5+ | St.Joseph-Rex | Independent | , | |
| Louis? Schaub | schaub008--- | 1903 | 9/11 | Denver Grizzlies | Western League | , | |
| Frank Scheibeck | scheib001fra | 1903 | 4/30-6/9 | Rochester Bronchos | Eastern League | , | |
| Frank Scheibeck | scheib001fra | 1903 | 6/17-9/17 | Denver Grizzlies | Western League | , | |
| Adolph Scheizel | 1903 | Saugerties | Hudson River League | , | |||
| Bert Schils | schils001alb | 1903 | 5/20-6/15 | Crookston Crooks | Northern League | , | |
| Bert Schils | schils001alb | 1903 | +6/20-7/18+ | Fargo | Northern League | , | |
| Bert Schils | schils001alb | 1903 | +8/2-9/8 | Crookston Crooks | Northern League | , | |
| Larry Schlafly | schlaf001har | 1903 | 4/22-9/21 | Milwaukee Brewers | American Association | , | |
| Admiral Schlei | schlei001geo | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Melchoir Schlitter | schitt001mel | 1903 | 7/24-8/30 | Galveston Sand Crabs | South Texas League | , | |
| Ernie Schmaltz | schmal001ern | 1903 | 5/7 | New London Whalers | Connecticut League | , | |
| Claude Schmeer | schmee001cla | 1903 | 27 g. | Portland Browns | Pacific Coast League | , | |
| Schmidt | schmid005--- | 1903 | +8/-8/20+ | Columbia | Tennessee-Alabama League | , | |
| Boss Schmidt | schmid001cha | 1903 | 5/1-5/ | 14 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , |
| Boss Schmidt | schmid001cha | 1903 | 5/25-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Henry Schmidt | schmid004hen | 1903 | 41 g. | Brooklyn | National League | Brooklyn, NY | |
| August Schnack | 1903 | 5/23-9/27 | Hudson Marines | Hudson River League | , | ||
| Frank Schneiberg | schnei001fra | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| Fred Schock | schock001fre | 1903 | 11 g. | Seattle Siwashes | Pacific Coast League | , | |
| Fred Schock | schock001fre | 1903 | Everett WA | Independent | , | ||
| Schoenfeld | schoen006--- | 1903 | 8/15-8/17 | Holyoke Paperweights | Connecticut League | , | |
| Emmett Schofield | schofi001emm | 1903 | Petaluma | California State League | , | ||
| Thomas Schoonhoven | schoon001tho | 1903 | 44 g. | Quincy-Reserves | Independent | , | |
| Grant Schopp | schopp001gra | 1903 | 5/2-5/27 | Leavenworth White Sox | Missouri Valley League | , | |
| Grant Schopp | schopp001gra | 1903 | 6/8-7/24 | McCook | Central Nebraska League | , | |
| Charles Schott | schott000cha | 1903 | 8/1 | New Orleans Pelicans | Southern Association | , | |
| Joe Schrall | schral001jos | 1903 | 4/30-9/26 | Rochester Bronchos | Eastern League | , | |
| John Schrant | schran001joh | 1903 | 5/4-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| Ossee Schrecongost | schrec001oss | 1903 | Philadelphia | American League | Philadelphia, PA | ||
| E. Schriber | 1903 | Poughkeepsie Colts | Hudson River League | , | |||
| Pop Schriver | schriv001wil | 1903 | 4/22-9/17 | Louisville Colonels | American Association | , | |
| Henry Schroeder | schroe001h-- | 1903 | 7/31-9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Tony Schubert | schube000ton | 1903 | Ionia MI | Independent | , | ||
| Frank Schulte | schult001fra | 1903 | 5/8-9/20 | Syracuse Stars | New York State League | , | |
| Henry Schulte | schult001hen | 1903 | 7/16-8/14+ | Crookston Crooks | Northern League | , | |
| Schultz | schult022--- | 1903 | 9 g. | Kingston Colonials | Hudson River League | , | |
| Schumann | schuma010--- | 1903 | 7/2 | Troy Trojans | New York State League | , | |
| Hack Schumann | schuma002car | 1903 | 5/6-6/2 | Newark Sailors | Eastern League | , | |
| Hack Schumann | schuma002car | 1903 | 7/2 | Concord Marines | New England League | , | |
| Hack Schumann | schuma002car | 1903 | 7/6-7/17 | Hartford Senators | Connecticut League | , | |
| Jack Schuster | schust001--- | 1903 | 8/3 | New Orleans Pelicans | Southern Association | , | |
| Jack Schuster | schust001--- | 1903 | 8/16-8/19 | Galveston Sand Crabs | South Texas League | , | |
| Joseph Schwab | schwab001jos | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Matty Schwab | schwab001mat | 1903 | Cincinnati | National League | Cincinnati, OH | ||
| Bill Schwartz | schwar003wil | 1903 | East Akron OH | Independent | , | ||
| Charles Schwartz | schwar001cha | 1903 | 104 g. | Oakland Oaks | Pacific Coast League | , | |
| Charles Schwartz | schwar001cha | 1903 | 101 g. | Seattle Siwashes | Pacific Coast League | , | |
| Edward Schwartz | schwar003edw | 1903 | 5/10-9/6 | Hoquiam Perfect Gentlemen | Southwest Washington League | , | |
| Rudy Schwenck | schwen001rud | 1903 | 7/4-7/24 | Talladega Tigers | Alabama-Georgia League | , | |
| Rudy Schwenck | schwen001rud | 1903 | +8/11-8/13+ | Gadsden AL | Independent | , | |
| Rudy Schwenck | schwen001rud | 1903 | 8/20-9/11 | Pulaski | Tennessee-Alabama League | , | |
| John Scission | 1903 | +8/5+ | Amer. Indians | Independent | , | ||
| Arlo Scoggins | scoggi001arl | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Scott | scott-064--- | 1903 | 6/12-7/24 | Red Cloud | Central Nebraska League | , | |
| Dick Scott | scott-001amo | 1903 | 4/30-9/16 | Terre Haute Hottentots | Central League | , | |
| George Scott | scott-004geo | 1903 | 5/1-9/18 | Binghamton Bingoes | New York State League | , | |
| George Scott | scott-004geo | 1903 | 9/21 | Newark Sailors | Eastern League | , | |
| Jesse/Arthur? Scott | scott-063--- | 1903 | 5/21-5/22+ | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Tom Scott | scott-002tom | 1903 | Lisbon | Independent | , | ||
| Tom Scott | scott-002tom | 1903 | 7/21-7/24 | Grand Forks Forkers | Northern League | , | |
| Dan Scudder | 1903 | Hornellsville NY | Independent | , | |||
| William Scudder | scudde002--- | 1903 | +8/18+ | Williamsport PA | Independent | , | |
| Frank Sealts | 1903 | +9/5+ | Wapakoneta OH | Independent | , | ||
| Harry Sears | sears-001har | 1903 | +8/4-8/19 | Los Angeles | Pacific National League | , | |
| Merle Sears | sears-001mea | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Merle Sears | sears-001mea | 1903 | Elgin | , | |||
| Harry Seay | seay--001h-- | 1903 | 5/3-5/27 | Milwaukee Creams | Western League | , | |
| Jimmy Sebring | sebrin001jam | 1903 | 124 g. | Pittsburgh | National League | Pittsburgh, PA | |
| Doc Sechrist | sechri001doc | 1903 | , | ||||
| Seethe | seethe000--- | 1903 | 6/27 | Marion Oilworkers | Central League | , | |
| John Seibert | seiber002joh | 1903 | Marion Oilworkers | Central League | , | ||
| John Seibert | seiber002joh | 1903 | 4/30-8/9 | Marion Oilworkers | Central League | , | |
| Davy Seisler | seisle001dav | 1903 | 5/10-5/20 | Umpire | Central League | , | |
| Davy Seisler | seisle001dav | 1903 | 5/25 | Dayton Veterans | Central League | , | |
| Kip Selbach | selbac001alb | 1903 | 140 g. | Washington | American League | Washington, DC | |
| Charles Selby | selby-001cha | 1903 | 5/19,7/27-8/4 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Reed Self | self--004--- | 1903 | 4/25-5/15 | Galveston Sand Crabs | South Texas League | , | |
| G. W. Selig | selig-000gw- | 1903 | 7/30-8/1 | Dayton Veterans | Central League | , | |
| Sellers | 1903 | 8/22 | Lawrence Colts | New England League | , | ||
| Thomas Senior | 1903 | 4/30-5/5 | Umpire | Central League | , | ||
| John Sens | sens--001joh | 1903 | 8/1 | New Orleans Pelicans | Southern Association | , | |
| Paul Sentell | sentel001leo | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| Paul Sentell | sentel001leo | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Bert Senter | senter001--- | 1903 | , | ||||
| Hugo Sequist | 1903 | Creston Cyclones | Southwest Iowa League | , | |||
| Perry Sessions | sessio001per | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Perry Sessions | sessio001per | 1903 | 5/20-9/8 | Grand Forks Forkers | Northern League | , | |
| W. Sewall | 1903 | Poughkeepsie Colts | Hudson River League | , | |||
| Joe Shackleton | shackl001jos | 1903 | 5/8-8/13 | Utica Pent-Ups | New York State League | , | |
| Ed. Shafer | schaef001e-- | 1903 | Hampton IA | Independent | , | ||
| Ed. Shafer | schaef001e-- | 1903 | Fort Dodge IA | Independent | , | ||
| Shaffer | 1903 | 7/28-8/2 | Ilion Typewriters | New York State League | , | ||
| Charlie Shaffer | shaffe001cha | 1903 | 35 g. | Portland Browns | Pacific Coast League | , | |
| Charlie Shaffer | shaffe001cha | 1903 | 5/15-9/30+ | Butte Miners | Pacific National League | , | |
| Theodore Shaffer | shaffe001the | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| C. D. Shamel | shamel000cd- | 1903 | 5/22-5/26 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Luther Shanks | shanks001lut | 1903 | +5/16-7/13 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbCity, | |
| Luther Shanks | shanks001lut | 1903 | +7/23-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Dan Shannon | shanno004dan | 1903 | 4/30-7/31 | Umpire | Eastern League | , | |
| Dan Shannon | shanno004dan | 1903 | 8/10-8/22 | Umpire | Connecticut League | , | |
| Frank Shannon | shanno002fra | 1903 | 4/30-6/13 | Providence Grays | Eastern League | , | |
| Frank Shannon | shanno004dan | 1903 | 7/17-8/28 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Owen Shannon | shanno001owe | 1903 | 4/30-8/31 | Wheeling Stogies | Central League | , | |
| Owen Shannon | shanno001owe | 1903 | 9/5- | 9 g. | St. Louis | American League | St. Louis, MO |
| Spike Shannon | shanno003wil | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| Jack Sharrott | sharro001jac | 1903 | 7/7-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Jack Sharrott | sharro001jac | 1903 | Worcester MA | Independent | , | ||
| Shag Shaughnessy | shaugh001fra | 1903 | 7/21-8/18+ | Sioux City Soos | Iowa-South Dakota League | , | |
| August Shaumeyer | schaum001aug | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Clinton Shaver | shaver001g-- | 1903 | +4/13+ | Furman College | College | , | |
| Shaw | 1903 | 4/28-5/16 | Nashville Volunteers | Southern Association | , | ||
| Al Shaw | shaw--001alf | 1903 | 4/30-9/26 | Buffalo Bisons | Eastern League | , | |
| Frank Shaw | shaw--001fra | 1903 | 6/3-9/8 | Duluth Cardinals | Northern League | , | |
| Hunky Shaw | shaw--001roy | 1903 | 4/30-5/ | Dayton | Inland Empire League | , | |
| Hunky Shaw | shaw--001roy | 1903 | 5/28-6/14 | Colfax | Inland Empire League | , | |
| Hunky Shaw | shaw--001roy | 1903 | North Yakima WW | Independent | , | ||
| John Shaw | shaw--007joh | 1903 | 5/8-9/20 | Ilion Typewriters | New York State League | , | |
| Danny Shay | shay--001dan | 1903 | 193 g. | San Francisco Seals | Pacific Coast League | , | |
| Shea | shea--036--- | 1903 | Elmira-FatherMathew | Independent | , | ||
| Danny Shea | shea--001dan | 1903 | 90 g. | Portland Browns | Pacific Coast League | , | |
| Dennie Shea | shea--001den | 1903 | +4/26-8/2+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland/SLC, | |
| Jim Shea | 1903 | Elmira NY | Independent | , | |||
| John Shea | shea--001p-- | 1903 | 5/7-? | New London Whalers | Connecticut League | , | |
| Nap Shea | shea--001joh | 1903 | 4/30-9/26 | Newark Sailors | Eastern League | , | |
| Peter Shea | shea--001pet | 1903 | 5/8-5/9 | Binghamton Bingoes | New York State League | , | |
| John Shearon | shearo002joh | 1903 | 4/30-5/22 | Baltimore Orioles | Eastern League | , | |
| John Shearon | shearo002joh | 1903 | 6/2-6/30 | Rochester Bronchos | Eastern League | , | |
| John Shearon | shearo002joh | 1903 | 7/3-9/5 | Buffalo Bisons | Eastern League | , | |
| Dan Sheehan | sheeha001dan | 1903 | 4/25-5/17 | New Orleans Pelicans | Southern Association | , | |
| Dan Sheehan | sheeha001dan | 1903 | 7/16-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Dan Sheehan | sheeha001dan | 1903 | 7/20-9/25 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Tommy Sheehan | sheeha003tho | 1903 | 193 g. | Sacramento Senators | Pacific Coast League | , | |
| Roy Sheets | sheets001roy | 1903 | 5/1-9/12 | Haverhill Hustlers | New England League | , | |
| George Shelafo | shelaf001--- | 1903 | +8/1-8/2+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Sheldon, | |
| Ben Shelton | shelto001ben | 1903 | 4/25-8/18 | Corsicana Oil Citys | Texas League | , | |
| John Shepherd | 1903 | Vincennes Alices | Kentucky-Illinois-Tennessee League | , | |||
| George Sheppard | sheppa001geo | 1903 | 5/20-9/8 | Duluth Cardinals | Northern League | , | |
| Jack Sheridan | sherid001jac | 1903 | 5/21-? | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |
| Jack Sheridan | sherid001jac | 1903 | MLB Umpire | American League | , | ||
| John Sherman | sherma004--- | 1903 | Vincennes Alices | Kentucky-Illinois-Tennessee League | , | ||
| John Sherman | sherma004--- | 1903 | Jackson Railroaders | Kentucky-Illinois-Tennessee League | , | ||
| Ray Sherwood | sherwo001--- | 1903 | 5/10-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| Bill Shettsline | shetts001bil | 1903 | San Francisco Seals | Pacific Coast League | , | ||
| Charlie Shields | shield002cha | 1903 | 49 g. | Portland Browns | Pacific Coast League | , | |
| Chester Shields | 1903 | Red Lion PA | Independent | , | |||
| Chester Shields | 1903 | Coatesville PA | Independent | , | |||
| Herman Shincel | shince001her | 1903 | 5/1-5/23 | Haverhill Hustlers | New England League | , | |
| Herman Shincel | shince001her | 1903 | 5/29-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Morris Shincup | shinca000--- | 1903 | +8/22+ | Roch.-Meyer | Independent | , | |
| Will Shinners | 1903 | Ilion Typewriters | New York State League | , | |||
| Bill Shipke | shipke001wil | 1903 | 5/2-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Frank Shipp | shipp-000ski | 1903 | Whitman GA | Independent | , | ||
| Shippicasse | 1903 | Holland MI | Independent | , | |||
| George Shoch | shoch-001geo | 1903 | 4/30-5/11 | Providence Grays | Eastern League | , | |
| George Shoch | shoch-001geo | 1903 | 5/27-9/20 | Troy Trojans | New York State League | , | |
| Joe Shock | shock-000joe | 1903 | 5/23,9/9-9/10 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Short | short-009--- | 1903 | 6/16 | Red Cloud | Central Nebraska League | , | |
| Bob Short | short-001rob | 1903 | 5/15-6/26 | Springfield Ponies | Connecticut League | , | |
| Harry Shortel | 1903 | Buff.-Branch 20 | Independent | , | |||
| Ed Shortell | shorte001edw | 1903 | 5/8-9/20 | Schenectady Frog Alleys | New York State League | , | |
| Eugene Shour | shour-001eug | 1903 | 54 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| Shriver | shrive002--- | 1903 | 6/21 | Centralia Midgets | Southwest Washington League | , | |
| Caleb Shriver | shrive001cal | 1903 | U. West Virginia | College | , | ||
| Caleb Shriver | shrive001cal | 1903 | 6/24-9/15 | Wheeling Stogies | Central League | , | |
| William Shufelt | shufel001wil | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Frank Shugart | shugar001fra | 1903 | 4/28-5/18 | Peoria Distillers | Western League | , | |
| Frank Shugart | shugar001fra | 1903 | 5/20-9/17 | Omaha Indians | Western League | , | |
| Eddie Shultz | shultz001edw | 1903 | Williamsport PA | Independent | , | ||
| Henry Sickle | sickle001hen | 1903 | 5/18-5/19 | Leavenworth White Sox | Missouri Valley League | , | |
| Sidorpski | sidorp001--- | 1903 | 6/30-7/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Johnny Siegle | siegle001joh | 1903 | 5/8-9/20 | Ilion Typewriters | New York State League | , | |
| Louis Siercovich | 1903 | 7/11 | Galveston Sand Crabs | South Texas League | , | ||
| Ed Siever | siever001edw | 1903 | St. Louis | American League | St. Louis, MO | ||
| Silva | silva-001--- | 1903 | +6/15+ | Oakl.-Haywards | Independent | , | |
| Silvester | 1903 | 8/17 | Brockton/New Bedford Whalers | New England League | New Bedford, | ||
| Joseph Silvia | 1903 | 7/24-9/5 | Brockton/New Bedford Whalers | New England League | New Bedford, | ||
| Hiram Simmons | 1903 | 6/3-6/6 | Lawrence Colts | New England League | , | ||
| Hank Simon | simon-001hen | 1903 | 5/8-9/20 | Utica Pent-Ups | New York State League | , | |
| Simons | 1903 | 7/23-8/3 | Hartford Senators | Connecticut League | , | ||
| Ben Simonton | simont001ben | 1903 | 5/1-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Ben Simonton | simont001ben | 1903 | 5/30-9/13 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Ben Simonton | simont001ben | 1903 | Urbana OH | Independent | , | ||
| H. Sintz | 1903 | Poughkeepsie Colts | Hudson River League | , | |||
| Carl Sitton | sitton001car | 1903 | +7/1-8/15 | Augusta GA | Independent | , | |
| Carl Sitton | sitton001car | 1903 | 8/18- | Tampa FL | Independent | , | |
| Henry Sitton | 1903-06 | +4/12+ | Clemson Col. | College | , | ||
| John Sixsmith | sixsmi000joh | 1903 | 6/3-6/13 | Binghamton Bingoes | New York State League | , | |
| John Sixsmith | sixsmi000joh | 1903 | 7/3-7/15 | Hartford Senators | Connecticut League | , | |
| Walter Sizemore | sizemo001wal | 1903 | 6/5 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Walter Sizemore | sizemo001wal | 1903 | 6/10-7/7+ | Leavenworth White Sox | Missouri Valley League | , | |
| Tom Skelley | skelle001--- | 1903 | Holy Cross | College | , | ||
| Tom Skelley | skelle001--- | 1903 | Claremont NH | Independent | , | ||
| James Skidmore | skidmo001jam | 1903 | Fort Riley KS | Army | , | ||
| James Skidmore | skidmo001jam | 1903 | Parsons KS | Independent | , | ||
| Skipper | 1903 | 7/7-7/10 | Galveston Sand Crabs | South Texas League | , | ||
| John Skopec | skopec001joh | 1903 | -9/11 | 6 g. | Detroit | American League | Detroit, MI |
| Walt Slagle | slagle001wal | 1903 | 10 g. | Portland Browns | Pacific Coast League | , | |
| Walt Slagle | slagle001wal | 1903 | +5/17-10/4 | Spokane Indians | Pacific National League | , | |
| Asa Slater | slater001asa | 1903 | Ottawa College | College | , | ||
| Ed Slater | slater001hen | 1903 | 5/8-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Jack Slattery | slatte001joh | 1903 | 4/24-5/8 | Columbus Senators | American Association | , | |
| Jack Slattery | slatte001joh | 1903 | 4 g. | Cleveland | American League | Cleveland, OH | |
| Jack Slattery | slatte001joh | 1903 | 63 g. | Chicago | American League | Chicago, IL | |
| Thomas Slattery | slatte000tho | 1903 | Springfield Midgets | Missouri Valley League | , | ||
| Frank Slavin | 1903 | +6/1+ | Portl-All Stars | Independent | , | ||
| Walter Slear | slear-001wal | 1903 | 4/30-9/15 | Fort Wayne Railroaders | Central League | , | |
| Ike Slette | slette001isa | 1903 | 5/21-8/15+ | Grand Forks Forkers | Northern League | , | |
| Fred Smeltz | 1903 | Ohio-Indep | Independent | , | |||
| Bill Smink | smink-001wil | 1903 | 11 g. | Kingston Colonials | Hudson River League | , | |
| Bill Smink | smink-001wil | 1903 | 5/8-5/12 | Ilion Typewriters | New York State League | , | |
| Bill Smink | smink-001wil | 1903 | 5/20-9/2 | Utica Pent-Ups | New York State League | , | |
| Booker Smiser | smiser000boo | 1903 | Mooney School | Independent | , | ||
| Booker Smiser | smiser000boo | 1903 | +5/29-8/5 | Columbia TN | Independent | , | |
| Booker Smiser | smiser000boo | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Booker Smiser | smiser000boo | 1903 | +8/21-8/28+ | Columbia | Tennessee-Alabama League | , | |
| Smith | smith-371--- | 1903 | 5/2 | Joplin Miners | Missouri Valley League | , | |
| Smith | smith-372--- | 1903 | 9/11 | Joplin Miners | Missouri Valley League | , | |
| Smith | 1903 | 6/11 | Nashua | New England League | , | ||
| Smith | smith-301--- | 1903 | 7/28-8/8 | Hartford Senators | Connecticut League | , | |
| Smith | smith-329--- | 1903 | Whatcom WA | Independent | , | ||
| Smith | smith-329--- | 1903 | 8/4-8/15+ | Seattle Chinooks | Pacific National League | , | |
| Smith | smith-345--- | 1903 | 9/6 | Dayton Veterans | Central League | , | |
| Aleck Smith | smith-001ale | 1903 | 11 g. | Boston | American League | Boston, MA | |
| Arthur Smith | smith-008art | 1903 | 5/9- | Haverhill Hustlers | New England League | , | |
| Arthur Smith | smith-008art | 1903 | -9/12 | Manchester | New England League | , | |
| Arthur Smith | smith-007art | 1903 | 5/8-8/10 | Binghamton Bingoes | New York State League | , | |
| Arthur Smith | smith-007art | 1903 | 8/14-9/20 | Albany Senators | New York State League | , | |
| Arthur Smith | smith-012art | 1903 | 5/20-5/23 | Leavenworth White Sox | Missouri Valley League | , | |
| August Smith | smith-001aug | 1903 | 13 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Billy Smith | smith-011wil | 1903 | Greenville Grays | Cotton States League | , | ||
| Billy Smith | smith-057wil | 1903 | 5/1-9/20 | Toledo Mud Hens | American Association | , | |
| Carlos Smith | smith-006car | 1903 | 162 g. | Seattle Siwashes | Pacific Coast League | , | |
| Carlos Smith | smith-006car | 1903 | 31 g. | Portland Browns | Pacific Coast League | , | |
| Charles Smith | smith-006cha | 1903 | 47 g. | Cedar Rapids Rabbits | Illinois-Indiana-Iowa League | , | |
| Charles Smith | 1903 | Oregon IA | Independent | , | |||
| Charlie Smith | smith-011cha | 1903 | 4/25-7/28 | New Orleans Pelicans | Southern Association | , | |
| Charlie Smith | smith-057cha | 1903 | +5/30+ | Sault Ste, Marie | Independent | , | |
| Cliff Smith | 1903 | +9/7+ | Columbus GA | Independent | , | ||
| Dexter Smith | 1903 | 6/10- | Umpire | Pacific National League | , | ||
| Dick Smith | smith-018ric | 1903 | 63 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Dick Smith | smith-005dic | 1903 | Norristown PA | Independent | , | ||
| Dick Smith | smith-005dic | 1903 | 5/1-5/5 | Lawrence Colts | New England League | , | |
| Ed Smith | smith-001rhe | 1903 | 23 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Ed Smith | smith-001ed- | 1903 | San Francisco | California State League | , | ||
| Ed Smith | smith-005ed- | 1903 | 7/24-9/11 | Wheeling Stogies | Central League | , | |
| Elmer Smith | smith-004elm | 1903 | 4/22-4/26 | Kansas City Cowboys | American Association | , | |
| Elmer Smith | smith-004elm | 1903 | Minneapolis Millers | American Association | , | ||
| Elmer Smith | smith-004elm | 1903 | 8/7-9/12 | Columbus Senators | American Association | , | |
| Elmer Smith | smith-005elm | 1903 | 4/19- | 38 g. | Butte Miners | Pacific National League | , |
| Elmer Smith | smith-005elm | 1903 | 7/2-8/9 | Springfield Midgets | Missouri Valley League | , | |
| Frank Smith | smith-008fra | 1903 | 4/27-9/5 | Birmingham Barons | Southern Association | , | |
| Frank Smith | smith-004fra | 1903 | 54 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| Frank Smith | smith-002f-- | 1903 | Holland MI | Independent | , | ||
| Fred Smith | smith-010fre | 1903 | 5/1-9/16 | Terre Haute Hottentots | Central League | , | |
| Fred Smith | 1903 | Umpire | Hudson River League | , | |||
| George Smith | smith-012geo | 1903 | 93 g. | Detroit | American League | Detroit, MI | |
| George Smith | smith-012geo | 1903 | 8/27-9/26 | Rochester Bronchos | Eastern League | , | |
| George Smith | 1903 | Saugerties | Hudson River League | , | |||
| George Smith | smith-020geo | 1903 | 5 g. | Oakland Oaks | Pacific Coast League | , | |
| Germany Smith | smith-013geo | 1903 | Altoona PA | Independent | , | ||
| H. G. Smith | 1903 | 6/18-6/22 | Lawrence Colts | New England League | , | ||
| Harry Smith | smith-018har | 1903 | 61 g. | Pittsburgh | National League | Pittsburgh, PA | |
| Harry Smith | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Herbert Smith | smith-005her | 1903 | 5/11-9/13 | South Bend Greens | Central League | , | |
| James Smith | 1903 | Saugerties | Hudson River League | , | |||
| James Smith | 1903 | Umpire | Hudson River League | , | |||
| Joe Smith | smith-007jos | 1903 | +8/26+ | Penn Park PA | Independent | , | |
| Joe Smith | smith-007jos | 1903 | +8/26+ | York PA | Independent | , | |
| John Smith | smith-024joh | 1903 | 5/7-9/3 | New London Whalers | Connecticut League | , | |
| John Smith | smith-035joh | 1903 | 4 g. | Seattle Siwashes | Pacific Coast League | , | |
| Jud Smith | smith-001jud | 1903 | 198 g. | Los Angeles Angels | Pacific Coast League | , | |
| Lester Smith | smith-003les | 1903 | Eagle Lake TX | Independent | , | ||
| Lester Smith | smith-003les | 1903 | 7/4-8/31 | Houston Buffaloes | South Texas League | , | |
| Otto Smith | smith-002ott | 1903 | 6/3-6/7 | Galveston Sand Crabs | South Texas League | , | |
| Otto Smith | smith-002ott | 1903 | 7/11 | Beaumont Oil Gushers | South Texas League | , | |
| Phenomenal Smith | smith-013joh | 1903 | 5/1-8/28 | Manchester | New England League | , | |
| Robert Smith | 1903 | 4/28-5/22 | Kansas City Blue Stockings | Western League | , | ||
| Samuel Smith | smith-007sam | 1903 | 9/12- | Youngstown OH | Independent | , | |
| Stub Smith | smith-001stu | 1903 | 5/25-5/17 | New Orleans Pelicans | Southern Association | , | |
| Stub Smith | smith-001stu | 1903 | 5/18-9/20 | Shreveport Giants | Southern Association | , | |
| Tom Smith | smith-001tho | 1903 | 5/2-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Tom Smith | smith-009tom | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| Herbert Smithson | donova043--- | 1903 | 5/20-7/1+ | Fargo | Northern League | , | |
| Herbert Smithson | donova043--- | 1903 | Portage la Pairie | Manitobe | , | ||
| Herbert Smithson | donova043--- | 1903 | Hartford Senators | Connecticut League | , | ||
| Presley Smithwick | smithw001p-- | 1903 | Memp.-Chickasawa | Independent | , | ||
| Presley Smithwick | smithw001p-- | 1903 | 7/25- | Huntsville TN | Independent | , | |
| Presley Smithwick | smithw001p-- | 1903 | 8/11-9/12 | Huntsville | Tennessee-Alabama League | , | |
| Homer Smoot | smoot-001hom | 1903 | 129 g. | St. Louis | National League | St. Louis, MO | |
| Harry Smythe | smythe003har | 1903 | U. New Hampshire | College | , | ||
| Snodgrass | snodgr004--- | 1903 | +5/1+ | 9 g. | Montgomery Black Sox | Interstate League | , |
| Snodgrass | snodgr004--- | 1903 | +8/4+ | Dalton GA | Independent | , | |
| Snodgrass | snodgr001--- | 1903 | 8/25- | Pulaski | Tennessee-Alabama League | , | |
| Walter Snodgrass | snodgr002wal | 1903 | +6/9+ | Urbana OH | Independent | , | |
| George Snoke | snoke-000mas | 1903 | Coatesville PA | Independent | , | ||
| George Snoke | snoke-000mas | 1903 | Pottstown PA | Independent | , | ||
| Joe Snooks | snooks001jos | 1903 | Pine Bluff Lumbermen | Cotton States League | , | ||
| Joe Snooks | snooks001jos | 1903 | +8/30+ | Fort Dodge IA | Independent | , | |
| O. H. Snyder | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Scott Snyder | snyder001sco | 1903 | Waterloo | Iowa League | , | ||
| Scott Snyder | snyder001sco | 1903 | Fort Dodge | Iowa League | , | ||
| Van Snyder | snyder002c-- | 1903 | Red Oak | Independent | , | ||
| William Snyder | snyder006wil | 1903 | Newark OH | Independent | , | ||
| William Snyder | snyder006wil | 1903 | 9/3-9/14 | Columbus Senators | American Association | , | |
| Louis Sockalexis | sockal001chi | 1903 | 6/6 | 1 ab | Whitinsville | Independent | , |
| Gus Soffel | soffel001aug | 1903 | 5/1-9/12 | Nashua | New England League | , | |
| Gus Soffel | soffel001aug | 1903 | 9/21-9/23 | Buffalo Bisons | Eastern League | , | |
| Thomas Solan | solan-001tho | 1903 | 5/21-6/1 | Superior Longshoremen | Northern League | , | |
| Percy Solbraa | 1903 | Clinton IA | Independent | , | |||
| Arthur Somers | somers005--- | 1903 | Atlantic City NJ | Independent | , | ||
| Arthur Somers | somers000art | 1903 | 4/18 | Seattle Chinooks | Pacific National League | , | |
| Arthur Somers | somers000art | 1903 | 4/30-6/14 | Colfax | Inland Empire League | , | |
| Arthur Somers | somers000art | 1903 | 2 g. | Roseberg OR | Independent | , | |
| Arthur Somers | somers000art | 1903 | +7/11+ | Eugene | Willamette Valley | Eugene, OR | |
| Byron Somers | somers000byr | 1903 | Chic.-Guthers | Independent | , | ||
| Byron Somers | somers000byr | 1903 | FtWa-Shamrocks | Independent | , | ||
| Byron Somers | somers000byr | 1903 | Fort Wayne Railroaders | Central League | , | ||
| Sommers | 1903 | 8/15-8/22 | Albany Senators | New York State League | , | ||
| Pete Sommers | sommer002pet | 1903 | 6/10-6/18 | Terre Haute Hottentots | Central League | , | |
| Sox Sorber | sorber001wal | 1903 | 6/16-7/26 | Umpire | Southern Association | , | |
| Sox Sorber | sorber001wal | 1903 | +8/15-9/4+ | Decatur | Tennessee-Alabama League | , | |
| Walter Sorenson | sorens001wal | 1903 | Utah State League | , | |||
| C. Van Sorrell | sorrel003--- | 1903 | 6/12-6/17+ | Talladega Tigers | Alabama-Georgia League | , | |
| Quinton Sorrell | 1903 | Auburn Univ. | College | , | |||
| William Sorrells | sorrel003wil | 1903 | 4/25-5/31 | Fort Worth Panthers | Texas League | , | |
| William Sorrells | sorrel003wil | 1903 | 8/6-8/31 | Houston Buffaloes | South Texas League | , | |
| Holly Souders | souder001har | 1903 | 5/1-5/26 | Baltimore Orioles | Eastern League | , | |
| Holly Souders | souder001har | 1903 | 6/12-6/27 | Kansas City Cowboys | American Association | , | |
| Holly Souders | souder001har | 1903 | 8/6 | Omaha Indians | Western League | , | |
| Soxalexis | soxale000--- | 1903 | 8/23 | Wheeling Stogies | Central League | , | |
| Soxalexis | soxale000--- | 1903 | 8/23 | Wheeling Stogies | Central League | , | |
| Alva Spangler | spangl001alv | 1903 | 4/30-9/16 | South Bend Greens | Central League | , | |
| Tully Sparks | sparks001tho | 1903 | Philadelphia | National League | Philadelphia, PA | ||
| Tully Sparks | sparks001tho | 1903 | 8/6 | Anniston AL | Independent | , | |
| Frank Spates | spates001fra | 1903 | Frostburg | Independent | , | ||
| Frank Speck | speck-000fra | 1903 | 5/8-5/14,9/7 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Ross Speck | speck-001ros | 1903 | 6/21- | Bartlesville OK | Independent | , | |
| Charles Speckin | 1903 | +7/15+ | Shenandoah | Southwest Iowa League | , | ||
| George Speer | speer-001geo | 1903 | 4/22-9/16 | Milwaukee Brewers | American Association | , | |
| Speidell | 1903 | +5/25-6/14 | Pendleton | Inland Empire League | , | ||
| William Spelliscy | spelli001wil | 1903 | U. ND Agricultural | College | , | ||
| William Spelliscy | spelli001wil | 1903 | 5/20-9/8 | Superior Longshoremen | Northern League | , | |
| Collis Spencer | spence001col | 1903 | Cumberland Univ | College | , | ||
| Collis Spencer | spence001col | 1903 | +6/12+ | Columbia TN | Independent | , | |
| Collis Spencer | spence001col | 1903 | Dalton GA | Independent | , | ||
| Collis Spencer | spence001col | 1903 | +8/14-8/21+ | Columbia | Tennessee-Alabama League | , | |
| Dit Spencer | spence001d-- | 1903 | 6/26-6/27 | Corsicana Oil Citys | Texas League | , | |
| Frank Spencer | spence001fra | 1903 | +8/12-9/29+ | Seattle Chinooks | Pacific National League | , | |
| Harry Spencer | spence001hen | 1903 | San Francisco | California State League | , | ||
| Harry Spencer | spence001hen | 1903 | 1 g. | Oakland Oaks | Pacific Coast League | , | |
| Wirt Spencer | spence001wir | 1903 | Umpire | Texas League | , | ||
| Spevy | 1903 | Dalton | , | ||||
| Harry Spies | spies-001hen | 1903 | 184 g. | Los Angeles Angels | Pacific Coast League | , | |
| Matt Spiesman | spiesm002mat | 1903 | 5/2-5/26 | Newark Sailors | Eastern League | , | |
| Matt Spiesman | spiesm002mat | 1903 | 5/28-7/24 | Albany Senators | New York State League | , | |
| Matt Spiesman | spiesm002mat | 1903 | 7/25-9/11 | Newark Sailors | Eastern League | , | |
| Matt Spiesman | spiesm002mat | 1903 | 9/18-9/26 | Rochester Bronchos | Eastern League | , | |
| George Spooner | spoone001geo | 1903 | 5/1-9/21 | Minneapolis Millers | American Association | , | |
| James Spooner | spoone001jam | 1903 | 4/25-5/10 | New Orleans Pelicans | Southern Association | , | |
| Joseph Sporer | sporer001jos | 1903 | 4/24-5/17 | Minneapolis Millers | American Association | , | |
| Jack Spratt | spratt001wil | 1903 | 4/27-9/19 | Montgomery Black Sox | Southern Association | , | |
| Jimmy Spring | 1903 | Holy Cross Col. | College | , | |||
| Jimmy Spring | 1903 | Burlington | Northern New York League | , | |||
| Fred Springs | spring001fre | 1903 | NC | Independent | , | ||
| Roy St. John | stjohn001roy | 1903 | 5/2-7/11 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Roy St. John | stjohn001roy | 1903 | 7/26-9/8 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Jim St. Vrain | stvrai001jam | 1903 | 4/22-5/15 | Minneapolis Millers | American Association | , | |
| Jim St. Vrain | stvrai001jam | 1903 | 6/4-8/16 | Tacoma Tigers | Pacific National League | , | |
| Jim St. Vrain | stvrai001jam | 1903 | 23 g. | Seattle Siwashes | Pacific Coast League | , | |
| Cy Stackpole | stackp001art | 1903 | 5/2-7/21 | Haverhill Hustlers | New England League | , | |
| James Stafford | staffo001gen | 1903 | 4/30-9/26 | Providence Grays | Eastern League | , | |
| Robert Stafford | staffo003rob | 1903 | 4/27-9/20 | Atlanta Crackers | Southern Association | , | |
| Chick Stahl | stahl-001cha | 1903 | 77 g. | Boston | American League | Boston, MA | |
| Jake Stahl | stahl-001gar | 1903 | 6/6- | 40 g. | Boston | American League | Boston, MA |
| Stallings | stalli002--- | 1903 | 6/10-6/18 | Hartford Senators | Connecticut League | , | |
| George Stallings | stalli002geo | 1903 | 4/30-9/26 | Buffalo Bisons | Eastern League | , | |
| Everett Stalter | stalte001eve | 1903 | Peekskill | Hudson River League | , | ||
| Oscar Stanage | stanag001osc | 1903 | Stockton | California State League | , | ||
| Tom Stankard | stanka001tho | 1903 | Holy Cross Col. | College | , | ||
| Tom Stankard | stanka001tho | 1903 | Lebanon NH | Independent | , | ||
| Stanley | stanle020--- | 1903 | 5/14-5/23 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Joe Stanley | stanle003jos | 1903 | 86 g. | Boston | National League | Boston, MA | |
| Matt Stanley | stanle001mat | 1903 | 120 g. | Seattle Chinooks | Pacific National League | , | |
| Roy Staples | 1903 | 1 g. | Crookston Crooks | Northern League | , | ||
| Claude Stark | stark-001cla | 1903 | 90 g. | Rockford Red Sox | Illinois-Indiana-Iowa League | , | |
| William Stark | stark-003wil | 1903 | 5/9-5/20 | Hartford Senators | Connecticut League | , | |
| William Stark | stark-003wil | 1903 | 6/3 | New London Whalers | Connecticut League | , | |
| Con Starkel | starke001con | 1903 | 7/12-9/6 | Olympia Senators | Southwest Washington League | , | |
| George Starnagle | starna001geo | 1903 | 4/28-8/6 | Colorado Springs Millionaires | Western League | , | |
| George Starnagle | starna001geo | 1903 | 9/17 | Colorado Springs Millionaires | Western League | , | |
| A. L. Starr | starr-001a-- | 1903 | 6/13-7/13 | Talladega Tigers | Alabama-Georgia League | , | |
| C. Stasanwald | 1903 | Poughkeepsie Colts | Hudson River League | , | |||
| Harry Stauffer | stauff001hen | 1903 | 56 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Danny Stearns | 1903 | 9/26 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | ||
| W. Stebbins | 1903 | Kingston Colonials | Hudson River League | , | |||
| A. L. Steele | steele013--- | 1903 | 5/24-8/9 | Olympia Senators | Southwest Washington League | , | |
| Carroll Steele | steele002car | 1903 | St. Albans College | College | , | ||
| Carroll Steele | steele002car | 1903 | +5/1+ | 8 g. | Montgomery Black Sox | Interstate League | , |
| Carroll Steele | steele002car | 1903 | 35 ab | Pine Bluff Lumbermen | Cotton States League | , | |
| Carroll Steele | steele002car | 1903 | 6/15-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Carroll Steele | steele002car | 1903 | +8/12+ | Anniston AL | Independent | , | |
| Carroll Steele | steele002car | 1903 | +8/20+ | 3 g. | Decatur | Tennessee-Alabama League | , |
| Fred Steele | steele001fre | 1903 | 5/21-5/22 | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Fred Steele | steele001fre | 1903 | 5/26-9/27 | Fort Scott Giants | Missouri Valley League | , | |
| Farmer Steelman | steelm001mor | 1903 | 5/1-5/22 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Farmer Steelman | steelm001mor | 1903 | 5/26-9/26 | Rochester Bronchos | Eastern League | , | |
| Steere | 1903 | 8/14 | Haverhill Hustlers | New England League | , | ||
| Steese | steese001--- | 1903 | +7/28-9/28+ | Harr.-Halifax | Independent | , | |
| Steese | steese001--- | 1903 | Harr.-Students | , | |||
| Michael Steffani | steffa001mic | 1903 | San Jose | California State League | , | ||
| Stein | stein-008--- | 1903 | Big Rapids MI | Independent | , | ||
| Ed Stein | stein-001ed- | 1903 | Detroit-Amat | Amateur | , | ||
| Paul Steinberg | steinb002pau | 1903 | Holyoke MA | , | |||
| Paul Steinberg | steinb002pau | 1903 | Franklin PA | , | |||
| Paul Steinberg | steinb002pau | 1903 | Holyoke MA | , | |||
| William Steinwender | steinw001--- | 1903 | USMA | College | , | ||
| William Steinwender | steinw001--- | 1903 | 33 g. | Los Angeles | Pacific National League | , | |
| W. R. Stephens | 1903 | Radcliffe | Independent | , | |||
| Louis Sterling | sterli001lou | 1903 | 9/4 | Utica Pent-Ups | New York State League | , | |
| Jay Stetler | stetle001per | 1903 | Williamsport PA | Independent | , | ||
| Stevenson | 1903 | 4/23-5/6+ | Spokane Indians | Pacific National League | , | ||
| Stevenson | 1903 | +5/23-6/14 | Dayton | Inland Empire League | , | ||
| Stevenson | 1903 | +8/13+ | Anniston AL | Independent | , | ||
| Stewart | stewar082--- | 1903 | 7/2-7/3 | Marion Oilworkers | Central League | , | |
| Ace Stewart | stewar001ace | 1903 | 4/30-5/17 | Omaha Indians | Western League | , | |
| Ace Stewart | stewar001ace | 1903 | 5/20-9/17 | Peoria Distillers | Western League | , | |
| Harry Stewart | stewar004har | 1903 | 7/1-9/12 | Norwich Reds | Connecticut League | , | |
| Joe Stewart | stewar003jos | 1903 | 4/26-9/10 | St. Paul Saints | American Association | , | |
| Henry Stickney | stickn001abr | 1903 | 4/27-6/6 | Montgomery Black Sox | Southern Association | , | |
| Henry Stickney | stickn001abr | 1903 | Greenville Grays | Cotton States League | , | ||
| Henry Stickney | stickn001abr | 1903 | 7/8-9/19 | Montgomery Black Sox | Southern Association | , | |
| Stier | 1903 | 9/22 | Baltimore Orioles | Eastern League | , | ||
| P. A. Stillman | 1903 | Rexburg | Idaho State League | , | |||
| Billy Stillwell | 1903 | 5/1 | Wheeling Stogies | Central League | , | ||
| Billy Stillwell | 1903 | +5/20+ | Wellsville OH | Independent | , | ||
| Archie Stimmel | stimme001arc | 1903 | Minneapolis Millers | American Association | , | ||
| Archie Stimmel | stimme001arc | 1903 | 8/11-9/20 | Milwaukee Brewers | American Association | , | |
| John Stinson | stinso001joh | 1903 | 5/3-7/10 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Alex Stirlith | stirli000ale | 1903 | Wilm.-Athletics | Independent | , | ||
| Otis Stocksdale | stocks002oti | 1903 | 6/7-9/17 | Montgomery Black Sox | Southern Association | , | |
| Amasa Stollenwerck | stolle001--- | 1903 | +4/3+ | Southern Univ. | College | , | |
| Amasa Stollenwerck | stolle001--- | 1903 | +7/7-8/18+ | Greensboro AL | Independent | , | |
| Stoller | 1903 | 9/4 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | ||
| Walter Stolworthy | stolwo000tom | 1903 | 6/3-7/21 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Walter Stolworthy | stolwo000tom | 1903 | 8/3-8/13 | Albany Senators | New York State League | , | |
| George Stone | stone-003geo | 1903 | 4/20- | 2 g. | Boston | American League | Boston, MA |
| George Stone | stone-003geo | 1903 | 6/7-9/17 | Milwaukee Creams | Western League | , | |
| Howard Stone | stone-001how | 1903 | Circleville OH | Independent | , | ||
| Howard Stone | stone-001how | 1903 | 7/3-7/15 | Milwaukee Brewers | American Association | , | |
| Herb Stoner | stoner001her | 1903 | Clinton IA | Independent | , | ||
| Herb Stoner | stoner001her | 1903 | 5/8-9/27 | Joplin Miners | Missouri Valley League | , | |
| Ed Stopher | stophe000--- | 1903 | +7/19-8/2 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Storey | 1903 | Harvard | College | , | |||
| Storey | 1903 | New London NH | Independent | , | |||
| Storey | 1903 | Woonsocket Gyms | Independent | , | |||
| Alan Storke | storke001ala | 1903-06 | Amherst Col. | College | , | ||
| Story | story-004--- | 1903 | 8/28 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Tom Stouch | stouch001tom | 1903 | U. of Alabama | College | , | ||
| Tom Stouch | stouch001tom | 1903 | 6/12-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Tom Stouch | stouch001tom | 1903 | 8/21-9/12 | Columbia | Tennessee-Alabama League | , | |
| Tom Stouch | stouch001tom | 1903 | no g. | Montgomery Black Sox | Southern Association | , | |
| Cy Stout | 1903 | , | |||||
| George Stovall | stoval001geo | 1903 | +5/28-6/14 | Walla Walla | Inland Empire League | , | |
| George Stovall | stoval001geo | 1903 | +7/15+ | Ogden UT | Independent | , | |
| George Stovall | stoval001geo | 1903 | Atlantic | Southwest Iowa League | , | ||
| Jesse Stovall | stoval001jes | 1903 | 3/26- | 5 g. | Seattle Siwashes | Pacific Coast League | , |
| Jesse Stovall | stoval001jes | 1903 | 4/14-8/20 | San Francisco Pirates | Pacific National League | , | |
| Jesse Stovall | stoval001jes | 1903 | 8/31- | 6 g. | Cleveland | American League | Cleveland, OH |
| Sammy Strang | strang001sam | 1903 | 135 g. | Brooklyn | National League | Brooklyn, NY | |
| Frank Strarup | straru000fra | 1903 | 7/11-7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbC, | |
| Milo Stratton | stratt001mil | 1903 | 5/4-6/30 | Memphis Egyptians | Southern Association | , | |
| Thomas Strayer | straye000tom | 1903 | Trenton NJ | Independent | , | ||
| Gabby Street | street001cha | 1903 | Hopkinsville Browns | Kentucky-Illinois-Tennessee League | , | ||
| Gabby Street | street001cha | 1903 | 9/10-9/12 | 4 g. | Huntsville | Tennessee-Alabama League | , |
| Julie Streib | streib001jul | 1903 | 4/28-9/17 | Kansas City Blue Stockings | Western League | , | |
| Theodore Streib | streib001the | 1903 | +4/19+ | Petaluma | California State League | , | |
| Oscar Streit | streit001osc | 1903 | 4/27-9/17 | Montgomery Black Sox | Southern Association | , | |
| Guy Stricker | 1903 | Clarinda | Southwest Iowa League | , | |||
| Elmer Stricklett | strick001elm | 1903 | 4/14-8/19 | Los Angeles | Pacific National League | , | |
| Elmer Stricklett | strick001elm | 1903 | +9/23-10/4 | Seattle Chinooks | Pacific National League | , | |
| Charles Strobel | strobe001cha | 1903 | Toledo Mud Hens | American Association | , | ||
| Billy Stroh | stroh-001wil | 1903 | 5//9-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| George Stroh | stroh-001geo | 1903 | 5/2- | Concord Marines | New England League | , | |
| George Stroh | stroh-001geo | 1903 | Haverhill Hustlers | New England League | , | ||
| George Stroh | stroh-001geo | 1903 | -8/27 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| George Stroh | stroh-001geo | 1903 | 9/1-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Con Strothers | stroth001joh | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Charles Strub | strub-001cha | 1903 | Oakland Reliance | California State League | , | ||
| Henry Stubblefield | stubbl001hen | 1903 | 4/25-8/30 | Galveston Sand Crabs | South Texas League | , | |
| William Stucke | stucke001w-- | 1903 | 5/2-6/22 | Springfield Midgets | Missouri Valley League | , | |
| William Stucke | stucke001w-- | 1903 | 6/27-7/22+ | Iola Gaslighters | Missouri Valley League | , | |
| William Stucke | stucke001w-- | 1903 | 5/2-6/22 | Springfield Midgets | Missouri Valley League | , | |
| William Stucke | stucke001w-- | 1903 | 6/27-7/22+ | Iola Gaslighters | Missouri Valley League | , | |
| George Stultz | stultz002geo | 1903 | 5/6-9/19 | Montgomery Black Sox | Southern Association | , | |
| Henry Stultz | stultz001hen | 1903 | Oakland Heeseman | California State League | , | ||
| Sturgis | 1903 | Amherst | College | , | |||
| Sturgis | 1903 | Littleton NH | Independent | , | |||
| Ed Stutsman | stutsm001e-- | 1903 | 6/16-6/18 | Duluth Cardinals | Northern League | , | |
| Sublet/t | 1903 | Furman | College | , | |||
| Joe Sugden | sugden001jos | 1903 | 79 g. | St. Louis | American League | St. Louis, MO | |
| George Suggs | suggs-001geo | 1903 | 5/8 | Nashua | New England League | , | |
| Sullivan | sulliv108--- | 1903 | 7/16 | Hartford Senators | Connecticut League | , | |
| Denny Sullivan | sulliv001den | 1903 | 5/20-7/4+ | Winnipeg Maroons | Northern League | , | |
| Denny Sullivan | sulliv001den | 1903 | 7/11-9/21 | Minneapolis Millers | American Association | , | |
| H. Thomas Sullivan | sulliv002h-- | 1903 | WaterlooIA | Independent | , | ||
| Jim Sullivan | sulliv006jam | 1903 | San Francisco | California State League | , | ||
| John Sullivan | sulliv004joh | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| John Sullivan | sulliv003joh | 1903 | 8/19-9/12 | Brockton/New Bedford Whalers | New England League | New Bedford, | |
| John Sullivan | sulliv001joh | 1903 | 56 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| M. L. Sullivan | 1903 | Dayton Veterans | Central League | , | |||
| M.J. Sullivan | sulliv000mj- | 1903 | Amateur | , | |||
| M.J. Sullivan | sulliv000mj- | 1903 | 8/17-9/11 | Norwich Reds | Connecticut League | , | |
| Mike Sullivan | sulliv005mic | 1903 | 5/7-6/27 | Hartford Senators | Connecticut League | , | |
| Mike Sullivan | sulliv005mic | 1903 | 7/7-7/25 | Meriden Silverites | Connecticut League | , | |
| Mike Sullivan | sulliv005mic | 1903 | 7/30-9/12 | Hartford Senators | Connecticut League | , | |
| Suter Sullivan | sulliv002sut | 1903 | 4/22-9/20 | Louisville Colonels | American Association | , | |
| Ted Sullivan | sulliv001tp- | 1903 | 4/25-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Ted Sullivan | sulliv001tp- | 1903 | 6/26-8/27 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Thomas Sullivan | sulliv050--- | 1903 | Rock Island Islanders | Illinois-Indiana-Iowa League | , | ||
| William Sullivan | 1903 | 5/1-9/12 | Umpire | New England League | , | ||
| Bill Sump | sump--001wil | 1903 | 5/8-6/5 | Syracuse Stars | New York State League | , | |
| Bill Sump | sump--001wil | 1903 | 6/27-6/28 | Birmingham Barons | Southern Association | , | |
| Bill Sump | sump--001wil | 1903 | Warren OH | Independent | , | ||
| Jack Sutthoff | suttho001joh | 1903 | 30 g. | Cincinnati | National League | Cincinnati, OH | |
| Harry Swacina | swacin001har | 1903 | 5/3-9/17 | Colorado Springs Millionaires | Western League | , | |
| Herbert Swaers | swaers000ber | 1903 | 5/10-6/7 | Lebanon IL | Independent | , | |
| Herbert Swaers | swaers000ber | 1903 | 8/26-9/27 | Joplin Miners | Missouri Valley League | , | |
| Arthur Swaim | swaim-001art | 1903 | 5/21-8/15+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Newt Swaim | swaim-000new | 1903 | 8/11-9/12 | Huntsville | Tennessee-Alabama League | , | |
| Newt Swaim | swaim-000new | 1903 | U. Alabama | College | , | ||
| Albert Swalm | swalm-001alb | 1903 | 6/16-6/19 | Fargo | Northern League | , | |
| Harry Swalm | swalm-001har | 1903 | Waterloo IA | Independent | , | ||
| Arthur Swan | swan--000cas | 1903 | Helena MT | Independent | , | ||
| Oscar Swan | swann-001o-- | 1903 | 5/1-9/16 | Shreveport Giants | Southern Association | , | |
| Pinky Swander | swande002edw | 1903 | 5/1-9/12 | Manchester | New England League | , | |
| Pinky Swander | swande002edw | 1903 | 9/18- | 14 g. | St. Louis | American League | St. Louis, MO |
| Ed Swartwood | swartw001ed- | 1903 | 5/7-9/25 | Umpire | Eastern League | , | |
| Alex. Sweeney | sweene001ale | 1903 | Williamsport PA | Independent | , | ||
| Edward Sweeney | sweene002edw | 1903 | Poughkeepsie Colts | Hudson River League | , | ||
| Michael Sweeney | sweene009mic | 1903 | Ossining/Catskill | Hudson River League | Ossining, | ||
| Patrick Sweeney | sweene001pat | 1903 | 8/30-9/15 | Wheeling Stogies | Central League | , | |
| Swift | swift-007--- | 1903 | 6/22 | Springfield Ponies | Connecticut League | , | |
| Robert Swiggert | 1903 | Northwestern U. | College | , | |||
| Charlie Swindells | swinde001cha | 1903 | 4/14-10/4 | Butte Miners | Pacific National League | , | |
| Ed Switzer | switze001j-- | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| Walter Swope | swope-001wal | 1903 | 5/9-9/10 | Nashua | New England League | , | |
| Len Swormstedt | sworms001leo | 1903 | 5/1-9/11 | Milwaukee Creams | Western League | , | |
| Louis Sylvester | sylves001lou | 1903 | 5/5-8/8 | Providence Grays | Eastern League | , | |
| Symonds | symond000--- | 1903 | 7/28 | Hartford Senators | Connecticut League | , | |
| Charles Symons | symons000cy- | 1903 | no g. | Crookston Crooks | Northern League | , | |
| Harry Tackaberry | tackab001har | 1903 | 4/25-4/30 | Houston Buffaloes | South Texas League | , | |
| Harry Tackaberry | tackab001har | 1903 | +4/12+ | Hous.-Cawthons | Amateur | , | |
| Harry Tackaberry | tackab001har | 1903 | 5/29- | Fort Worth Panthers | Texas League | , | |
| Harry Tackaberry | tackab001har | 1903 | -8/25 | Corsicana Oil Citys | Texas League | , | |
| Bob Talbot | talbot001rob | 1903 | St. Louis | American League | , | ||
| Frederic Taliafero | 1903 | Eugene | Willamette Valley | Eugene, OR | |||
| James Tamsett | tamset001jam | 1903 | 4/22-9/15 | Indianapolis Indians | American Association | , | |
| Jesse Tann | tann--000jes | 1903 | +7/4+ | Rock Springs WY | Independent | , | |
| Jesse Tann | tann--000jes | 1903 | +9/6+ | Park City UT | Independent | , | |
| Lee Tannehill | tanneh002lee | 1903 | Chicago | American League | Chicago, IL | ||
| Eugene Tansey | tansey001eug | 1903 | 5/8-9/12 | Springfield Ponies | Connecticut League | , | |
| Robert Tarleton | tarlet001rob | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| James Tarr | tarr--000jam | 1903 | 8/25-8/27 | Iola Gaslighters | Missouri Valley League | , | |
| Harry Tate | tate--001har | 1903 | Harrisburg PA | Independent | , | ||
| Hughie Tate | tate--001hug | 1903 | 8/5-9/16 | Dayton Veterans | Central League | , | |
| Ray Tate | 1903 | Fort Wayne Railroaders | Central League | , | |||
| Taylor | 1903 | 6/13-6/16 | Rochester Bronchos | Eastern League | , | ||
| Billy Taylor | taylor002bil | 1903 | 4/27-4/29 | Atlanta Crackers | Southern Association | , | |
| Billy Taylor | taylor002bil | 1903 | 1 g. | Seattle Siwashes | Pacific Coast League | , | |
| Billy Taylor | taylor002bil | 1903 | Spokane Indians | Pacific National League | , | ||
| Billy Taylor | taylor002bil | 1903 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | ||
| Cynthy Taylor | 1903 | 5/15-7/18 | Fall River Indians | New England League | , | ||
| Earl Taylor | taylor001ear | 1903 | 5/2-7/14 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbC, | |
| Ed Taylor | taylor001edg | 1903 | 8/8 | St. Louis | National League | St. Louis, MO | |
| Ed Taylor | taylor001edg | 1903 | 8/22 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Ed Taylor | taylor001edg | 1903 | 8/31 | San Antonio Bronchos | South Texas League | , | |
| Emmett Taylor | taylor000emm | 1903 | 6/30 | Little Rock Travelers | Southern Association | , | |
| John Taylor | taylor107--- | 1903 | Flandreau Indian | School | , | ||
| John Taylor | taylor107--- | 1903 | 7/21-8/30 | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Luther Taylor | taylor001lut | 1903 | New York | National League | New York, NY | ||
| Richard Taylor | taylor001ric | 1903 | 7/1-8/1 | Des Moines Undertakers | Western League | , | |
| Roy Taylor | taylor005r-- | 1903 | 5/4- | Concord Marines | New England League | , | |
| Roy Taylor | taylor005r-- | 1903 | -6/20 | Nashua | New England League | , | |
| Slats Taylor | taylor002vir | 1903 | +4/7+ | Yakima WA | Independent | , | |
| Slats Taylor | taylor002vir | 1903 | 4/30-5/14 | Pendleton | Inland Empire League | , | |
| Slats Taylor | taylor002vir | 1903 | 6/2- | Spokane Indians | Pacific National League | , | |
| Slats Taylor | taylor002vir | 1903 | 6/4- | Colfax | Inland Empire League | , | |
| Thomas Taylor | taylor002tho | 1903 | no g. | Albany Senators | New York State League | , | |
| Thomas Taylor | taylor002tho | 1903 | 5/8-7/31 | Binghamton Bingoes | New York State League | , | |
| Wally Taylor | taylor001wal | 1903 | 4/30-9/24 | Newark Sailors | Eastern League | , | |
| Joe Teabo | 1903 | Chernawa Indian | School | , | |||
| Joe Teabo | 1903 | Salem | Willamette Valley | Salem, OR | |||
| Harry Teal | teal--002har | 1903 | Natchez Indians | Cotton States League | , | ||
| Harry Teal | teal--002har | 1903 | 7/15-7/31 | Dayton Veterans | Central League | , | |
| Harvey Teal | teal--003har | 1903 | Paulding OH | Independent | , | ||
| Harvey Teal | teal--003har | 1903 | 5/1-5/13 | Fort Wayne Railroaders | Central League | , | |
| Al Tebeau | tebeau002al- | 1903 | 5/-6/20 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | |
| Al Tebeau | tebeau002al- | 1903 | 6/21-6/24 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | |
| George Tebeau | tebeau002geo | 1903 | Louisville Colonels | American Association | , | ||
| Delbert Teel | teel--001d-- | 1903 | 6/9-7/24 | Holdredge | Central Nebraska League | , | |
| Terrell | 1903 | 7/24-7/25 | San Antonio Bronchos | South Texas League | , | ||
| Ivey Tevis | tevis-001iva | 1903 | 4/26-8/30 | Beaumont Oil Gushers | South Texas League | , | |
| Ivey Tevis | tevis-001iva | 1903 | 8/31 | Galveston Sand Crabs | South Texas League | , | |
| Ivey Tevis | tevis-001iva | 1903 | 9/14 | Shreveport Giants | Southern Association | , | |
| Parry Thackara | thacka001dav | 1903 | no g. | Albany Senators | New York State League | , | |
| Parry Thackara | thacka001dav | 1903 | Pottstown PA | Independent | , | ||
| Grant Thatcher | thatch001uly | 1903 | 4/15-8/19 | Los Angeles | Pacific National League | , | |
| Grant Thatcher | thatch001uly | 1903 | 9/9- | 4 g. | Brooklyn | National League | Brooklyn, NY |
| Tony Thebo | thebo-001ant | 1903 | 4/25-8/24 | Corsicana Oil Citys | Texas League | , | |
| Tony Thebo | thebo-001ant | 1903 | Natchez Indians | Cotton States League | , | ||
| Joseph Theisen | theise001jos | 1903 | 5/7-9/12 | Meriden Silverites | Connecticut League | , | |
| Otto Thiel | thiel-001ott | 1903 | 4/28-9/17 | Peoria Distillers | Western League | , | |
| Henry Thielman | thielm001hen | 1903 | -5/15 | 9 g. | Brooklyn | National League | Brooklyn, NY |
| Henry Thielman | thielm001hen | 1903 | 6/4-9/26 | Jersey City Skeeters | Eastern League | , | |
| Jake Thielman | thielm001joh | 1903 | +4/25-7/3+ | Los Angeles | Pacific National League | , | |
| Jake Thielman | thielm001joh | 1903 | 45 g. | Portland Browns | Pacific Coast League | , | |
| Jack Thiery | thiery001joh | 1903 | 4/30-8/21 | Newark Sailors | Eastern League | , | |
| Jack Thiery | thiery001joh | 1903 | 8/29-9/26 | Buffalo Bisons | Eastern League | , | |
| Thomas | thomas037--- | 1903 | +7/31+ | Ionia MI | Independent | , | |
| Thomas | thomas110--- | 1903 | 6/21-7/8 | Terre Haute Hottentots | Central League | , | |
| Alphonse Thomas | thomas002alp | 1903 | 5/11-7/1 | Springfield Ponies | Connecticut League | , | |
| Benjamin Thomas | thomas001ben | 1903 | 12 g. | Sacramento Senators | Pacific Coast League | , | |
| Benjamin Thomas | thomas001ben | 1903 | , | ||||
| Bill Thomas | thomas007wil | 1903 | Harrisburg PA | Independent | , | ||
| Clifford Thomas | thomas001cli | 1903 | Clarksville Villagers | Kentucky-Illinois-Tennessee League | , | ||
| Dick Thomas | thomas000re- | 1903 | 4/25-8/31 | San Antonio Bronchos | South Texas League | , | |
| Frosty Thomas | thomas001for | 1903 | 4/25-9/19 | Minneapolis Millers | American Association | , | |
| G. Thomas | thomas002g-- | 1903 | 6/13-9/12 | Hartford Senators | Connecticut League | , | |
| Ira Thomas | thomas001ira | 1903 | 5/7-9/11 | Hartford Senators | Connecticut League | , | |
| Ira Thomas | thomas001ira | 1903 | 9/12-9/25 | Newark Sailors | Eastern League | , | |
| Jack Thomas | thomas007joh | 1903 | 5/2-9/17 | Omaha Indians | Western League | , | |
| James Thomas | thomas002jim | 1903 | +4/30-8/1+ | Ionia MI | Independent | , | |
| Joe Thomas | thomas001tho | 1903 | 4/18-6/9 | Los Angeles | Pacific National League | , | |
| Joe Thomas | thomas001tho | 1903 | 6/12-7/17+ | Butte Miners | Pacific National League | , | |
| Orth Thomas | thomas001ort | 1903 | 4/26-8/30 | San Antonio Bronchos | South Texas League | , | |
| Roy Thomas | thomas002roy | 1903 | Philadelphia | National League | Philadelphia, PA | ||
| Tom Thomas | thomas005tho | 1903 | 5/2-5/28 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Tom Thomas | thomas005tho | 1903 | 5/30-9/15 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Tom Thomas | thomas005tho | 1903 | Youngstown OH | Independent | , | ||
| William Thomas | thomas002wil | 1903 | 57 g. | Sacramento Senators | Pacific Coast League | , | |
| Thompson | thomps121--- | 1903 | 5/13 | Marion Oilworkers | Central League | , | |
| Thompson | thomps121--- | 1903 | Knightstown IN | Independent | , | ||
| Charles Thompson | 1903 | 5/14 | San Antonio Bronchos | South Texas League | , | ||
| Charles Thompson | 1903 | 6/20, 7/24 | Beaumont Oil Gushers | South Texas League | , | ||
| Curley Thompson | thomps000cur | 1903 | +5/28+ | Colfax | Inland Empire League | , | |
| George Thompson | thomps008geo | 1903 | San Antonio Bronchos | South Texas League | , | ||
| George Thompson | thomps008geo | 1903 | 6/17-7/1+ | Leavenworth White Sox | Missouri Valley League | , | |
| George Thompson | thomps008geo | 1903 | 7/13 | Fort Scott Giants | Missouri Valley League | , | |
| George Thompson | thomps008geo | 1903 | +7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Webb City, | |
| Gus Thompson | thomps007joh | 1903 | 4/14-8/16 | Helena Senators | Pacific National League | , | |
| Gus Thompson | thomps007joh | 1903 | 8/31- | 5 g. | Pittsburgh | National League | Pittsburgh, PA |
| Jack Thompson | thomps011joh | 1903 | 4/30-9/16 | Terre Haute Hottentots | Central League | , | |
| M. J. Thompson | thomps002m-- | 1903 | Norwich Reds | Connecticut League | , | ||
| Michael Thompson | 1903 | Georgetown Col | College | , | |||
| Jack Thoney | thoney001joh | 1903 | 5/9-7/7 | Columbus Senators | American Association | , | |
| Jack Thoney | thoney001joh | 1903 | 32 g. | Cleveland | American League | Cleveland, OH | |
| John Thornton | thornt003joh | 1903 | 4/28-7/26 | Milwaukee Creams | Western League | , | |
| John Thornton | thornt003joh | 1903 | 8/5-9/11 | Omaha Indians | Western League | , | |
| Ross Thornton | thornt001ros | 1903 | 107 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Ross Thornton | thornt001ros | 1903 | 9/15-9/16 | Terre Haute Hottentots | Central League | , | |
| Hal Thruman | 1903 | 4/27-5/15+ | Oklahoma City | Independent | , | ||
| Hal Thruman | 1903 | 5/25 | Fort Scott Giants | Missouri Valley League | , | ||
| Hal Thruman | 1903 | 6/4-6/19 | Pittsburg Coal Diggers | Missouri Valley League | , | ||
| Hal Thruman | 1903 | +7/7+ | Shawnee OK | Independent | , | ||
| Pat Tibald | tibald001pet | 1903 | 5/3-7/18 | Peoria Distillers | Western League | , | |
| Pat Tibald | tibald001pet | 1903 | 8/2-9/7 | Colorado Springs Millionaires | Western League | , | |
| J. Tieino | 1903 | Kingston Colonials | Hudson River League | , | |||
| George Tieman | tieman001geo | 1903 | 92 g. | South Bend Greens | Central League | , | |
| Tierney | tierne004mar | 1903 | Wilmington DE | Independent | , | ||
| Ray Tift | tift--001ray | 1903-07 | Brown Univ. | College | , | ||
| Jack Tighe | tighe-001joh | 1903 | 5/7-9/10 | Norwich Reds | Connecticut League | , | |
| William Tiley | 1903 | Shenandoah | Southwest Iowa League | , | |||
| Jimmy Tilford | tilfor001jam | 1903 | Louisville Colonels | American Association | , | ||
| Joe Tilford | tilfor001joe | 1903 | Umpire | Texas League | , | ||
| John Titus | titus-001joh | 1903 | 5/1-6/6 | Concord Marines | New England League | , | |
| John Titus | titus-001joh | 1903 | Philadelphia | National League | Philadelphia, PA | ||
| Stanley Titus | titus-004--- | 1903 | 6/11-6/14 | Walla Walla | Inland Empire League | , | |
| Stanley Titus | titus-004--- | 1903 | 6/28-8/16 | Centralia Midgets | Southwest Washington League | , | |
| Stanley Titus | titus-004--- | 1903 | 8/23-9/6 | Aberdeen Pippins | Southwest Washington League | , | |
| William Tobey | tobey-000wh- | 1903 | Brown Univ. | College | , | ||
| Jack Toft | toft--001jam | 1903 | 4/30-9/26 | Toronto Maple Leafs | Eastern League | , | |
| Jimmy Toman | toman-001jam | 1903 | 172 g. | Los Angeles Angels | Pacific Coast League | , | |
| Cy Torrence | torren001osc | 1903 | 5/2-7/8 | Terre Haute Hottentots | Central League | , | |
| Cy Torrence | torren001osc | 1903 | 9/13 | Evansville River Rats | Central League | , | |
| William Torrence | torren002wil | 1903 | 7/29-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Clarence Totman | totman001cla | 1903 | Piqua OH | Independent | , | ||
| Joseph Touhey | toohey001jos | 1903 | 7/8-7/18 | Columbus Senators | American Association | , | |
| Joseph Touhey | toohey001jos | 1903 | 7/25-9/26 | Rochester Bronchos | Eastern League | , | |
| Walter Towers | towers001wal | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| Babe Towne | towne-001jay | 1903 | 4/28-9/17 | Des Moines Undertakers | Western League | , | |
| Cy Townsend | townse002cha | 1903 | 176 g. | Sacramento Senators | Pacific Coast League | , | |
| Guy Townsend | townse001guy | 1903 | +7/15+ | Shenandoah | Southwest Iowa League | , | |
| Guy Townsend | townse001guy | 1903 | +7/26-7/27+ | Creston Cyclones | Southwest Iowa League | , | |
| Happy Townsend | townse001joh | 1903 | 20 g. | Washington | American League | Washington, DC | |
| Zob Townsend | townse000zob | 1903 | 6/8-7/24 | McCook | Central Nebraska League | , | |
| Zob Townsend | townse000zob | 1903 | +8/15+ | Lincoln YMCA | Independent | , | |
| Bill Tozer | tozer-001wil | 1903 | 5/25-6/3 | Butte Miners | Pacific National League | , | |
| Bill Tozer | tozer-001wil | 1903 | +6/26+ | Salt Lake City UT | Independent | , | |
| Bill Tozer | tozer-001wil | 1903 | +7/2-10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Tracey | 1903 | 5/21-5/22+ | Council Bluffs Bluffers/Sheldon-Primghar Hyphens | Iowa-South Dakota League | Council Bluffs, | ||
| Ralph Tracy | 1903 | Helena Senators | Pacific National League | , | |||
| Charles Traeger | traege002cha | 1903 | 5/20-9/8 | Fargo | Northern League | , | |
| George Treadway | treadw001geo | 1903 | 4/14-10/4 | Seattle Chinooks | Pacific National League | , | |
| Wix Treadway | treadw001win | 1903 | 5/21-8/11+ | Sioux City Soos | Iowa-South Dakota League | , | |
| Parker Treat | treat-001par | 1903 | 4/30-7/8 | Evansville River Rats | Central League | , | |
| Parker Treat | treat-001par | 1903 | 7/25-9/10 | Meriden Silverites | Connecticut League | , | |
| Burt Tree | tree--001bur | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Vere Treichler | treich001--- | 1903 | Jeff. Medical Col | College | , | ||
| Trestrall | trestr001--- | 1903 | KC-Schmelzers | Independent | , | ||
| Benjamin Tribble | 1903 | +7/24+ | Columbia SC | Independent | , | ||
| Trimble | trimbl002--- | 1903 | 5/10-5/22 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Robert Tritton | tritto001rob | 1903 | 8/10-9/15 | Birmingham Barons | Southern Association | , | |
| B. Trobough | 1903 | +8/20+ | Tobias NE | Independent | , | ||
| Del Trobough | trobou001del | 1903 | +6/11+ | Atlantic | Southwest Iowa League | , | |
| James Troy | troy--004jam | 1903 | 5/12-6/12 | Dayton Veterans | Central League | , | |
| Thad Troy | troy--001tha | 1903 | no g. | Wheeling Stogies | Central League | , | |
| Thad Troy | troy--001tha | 1903 | +7/30+ | Piqua OH | Independent | , | |
| Harry Truby | truby-002har | 1903 | 94 g. | Bloomington Bloomers | Illinois-Indiana-Iowa League | , | |
| Jonathan Trumbull | trumbu002--- | 1903 | 8/6-9/3 | New Haven Blues | Connecticut League | , | |
| Dave Tucker | tucker001dav | 1903 | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | ||
| Dave Tucker | tucker001dav | 1903 | St. Cloud MN | Independent | , | ||
| Fred Tucker | tucker001f-- | 1903 | Sayer football | , | |||
| Tom Tuckey | tuckey002tho | 1903 | 5/7-9/12 | New Haven Blues | Connecticut League | , | |
| Henry Tufts | tufts-001hen | 1903 | 4/25-6/25 | Houston Buffaloes | South Texas League | , | |
| Henry Tufts | tufts-001hen | 1903 | 6/30-8/26 | San Antonio Bronchos | South Texas League | , | |
| Paddy Tuohy | toohey001jam | 1903 | +9/20+ | Paterson NJ | Independent | , | |
| Turner | turner067--- | 1903 | 8/2 | Evansville River Rats | Central League | , | |
| Daniel Turner | turner003dan | 1903 | 5/2-9/20 | Toledo Mud Hens | American Association | , | |
| Terry Turner | turner001ter | 1903 | 4/22-9/20 | Columbus Senators | American Association | , | |
| Tuck Turner | turner002tuc | 1903 | 5/7-9/12 | Norwich Reds | Connecticut League | , | |
| Tuttle | 1903 | Paulding OH | Independent | , | |||
| Tyler | 1903 | 6/18-6/27 | Umpire | Connecticut League | , | ||
| Uhl | 1903 | 9/1 | St. Joseph Saints | Western League | , | ||
| Heiny Uhl | 1903 | Ogden UT | Independent | , | |||
| Ulmer | 1903 | 4/27 | Galveston Sand Crabs | South Texas League | , | ||
| Fred Ulrich | ulrich001fre | 1903 | 5/27-7/12 | Kansas City Blue Stockings | Western League | , | |
| Fred Ulrich | ulrich001fre | 1903 | 7/18-7/30 | Denver Grizzlies | Western League | , | |
| Fred Ulrich | ulrich001fre | 1903 | 8/12-9/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Umstead | 1903-05 | Cornell Univ | College | , | |||
| Bob Unglaub | unglau002rob | 1903 | 4/22-9/21 | Milwaukee Brewers | American Association | , | |
| Tommy Uniac | uniac-001tho | 1903 | 7/1-9/12 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| George Upp | upp---001geo | 1903 | no g. | Toledo Mud Hens | American Association | , | |
| Bill Urquhart | urquha001wil | 1903 | 5/8-9/17 | Syracuse Stars | New York State League | , | |
| Lon Ury | ury---001lou | 1903 | 4/26-8/25 | Dallas Giants | Texas League | , | |
| Lon Ury | ury---001lou | 1903 | 9/9-9/12 | St. Louis | National League | St. Louis, MO | |
| Jerome Utley | utley-001jer | 1903 | no g. | Washington | American League | Washington, DC | |
| Bob Vail | vail--001rob | 1903 | Colby College | College | , | ||
| Bob Vail | vail--001rob | 1903 | 6/2- | Nashua | New England League | , | |
| Bob Vail | vail--001rob | 1903 | -8/24 | Manchester | New England League | , | |
| Fred Valdois | valdoi001fre | 1903 | 5/1- | Nashua | New England League | , | |
| Fred Valdois | valdoi001fre | 1903 | -9/12 | Lawrence Colts | New England League | , | |
| Frederick Valentine | 1903 | 8/10-9/27 | Peekskill | Hudson River League | , | ||
| Edward Van Anda | vanand002edw | 1903 | -8/18 | Piqua OH | Independent | , | |
| Edward Van Anda | vanand002edw | 1903 | Paulding OH | Independent | , | ||
| Deacon Van Buren | vanbur001edw | 1903 | 205 g. | Portland Browns | Pacific Coast League | , | |
| Dow Van Dine | vandin001dow | 1903 | 102 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Van Dulin | 1903 | +7/26+ | Butte Miners | Pacific National League | , | ||
| William Van Leuwen | vanleu000wil | 1903 | Roseburg | Willamette Valley | Roseburg, OR | ||
| George Van Riper | 1903 | 19 g. | Kingston Colonials | Hudson River League | , | ||
| Sam Van Vecheen | 1903 | Ossining/Catskill | Hudson River League | Catskill, | |||
| Ike Van Zandt | vanzan001cha | 1903 | 5/1-5/30 | Nashua | New England League | , | |
| Ike Van Zandt | vanzan001cha | 1903 | Woonsocket-Gyms | Independent | , | ||
| Ike Van Zandt | vanzan001cha | 1903 | 9/14-9/20 | Utica Pent-Ups | New York State League | , | |
| Vanderberg | 1903 | 8/19-8/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | ||
| Anthony Vanderhill | vander001ant | 1903 | no g. | Kansas City Cowboys | American Association | , | |
| Anthony Vanderhill | vander001ant | 1903 | 5/2-5/30 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada, | |
| Joe VanderWeg | vander005--- | 1903 | Big Rapids MI | Independent | , | ||
| Dike Varney | varney001law | 1903 | 5/27 | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Cal Vasbinder | vasbin001mos | 1903 | 4/23-8/8 | Minneapolis Millers | American Association | , | |
| William Vaughan | vaugha004wil | 1903 | +6/9+ | Normal Alumni | Independent | , | |
| Farmer Vaughn | vaughn001far | 1903 | 4/27-9/20 | Birmingham Barons | Southern Association | , | |
| Phil Veatch | veach-001phi | 1903 | 8/12-8/27 | Umpire | Central League | , | |
| Bucky Veil | veil--001fre | 1903 | 4/19- | 12 g. | Pittsburgh | National League | Pittsburgh, PA |
| William Veley | 1903 | +5/14-6/14 | Dayton | Inland Empire League | , | ||
| Charles Venable | venabl001cha | 1903 | no g. | Pine Bluff Lumbermen | Cotton States League | , | |
| Perry Verga | verga-001geo | 1903 | +7/16+ | Camden NJ | Independent | , | |
| Charley Verheyden | 1903 | 6/21-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | ||
| Charley Verheyden | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | ||
| Lee Vernuelle | vernue001rob | 1903 | Natchez Indians | Cotton States League | , | ||
| Kangaroo Verstay | versta001--- | 1903 | Grand Rapids MI | Independent | , | ||
| Vesennier | 1903 | 8/2-8/7 | Kansas City Cowboys | American Association | , | ||
| George Vetter | vetter001geo | 1903 | Loui.-Goss | Independent | , | ||
| Phil Vetter | vetter001phi | 1903 | Loui.-Goss | Independent | , | ||
| Lee Viau | viau--001lee | 1903 | 5/2-9/25 | Providence Grays | Eastern League | , | |
| Rube Vickers | vicker001har | 1903 | 5/23-6/30 | Holyoke Paperweights | Connecticut League | , | |
| Rube Vickers | vicker001har | 1903 | 5 g. | Brooklyn | National League | Brooklyn, NY | |
| Rube Vickers | vicker001har | 1903 | 7/25-9/12 | Holyoke Paperweights | Connecticut League | , | |
| Sammy Vigneux | vignea001sam | 1903 | 71 g. | Portland Browns | Pacific Coast League | , | |
| George Villeman | villem001geo | 1903 | 5/3-9/17 | Colorado Springs Millionaires | Western League | , | |
| Vincent | 1903 | 5/14 | Schenectady Frog Alleys | New York State League | , | ||
| Rube Vinson | vinson001ern | 1903 | +8/18+ | Harrisburg PA | Independent | , | |
| Juan Viola | 1903 | 19 g. | Almendares | Cuban Winter League | , | ||
| Violet | 1903 | Jamestown NY | Independent | , | |||
| Rony Viox | viox--001hen | 1903 | 5/5-5/30 | Louisville Colonels | American Association | , | |
| Rony Viox | viox--001hen | 1903 | 6/19-9/21 | Milwaukee Brewers | American Association | , | |
| Harry Vitter | vitter001har | 1903 | 4/28-5/10 | Atlanta Crackers | Southern Association | , | |
| Harry Vitter | vitter001har | 1903 | 8/3-8/31 | Beaumont Oil Gushers | South Texas League | , | |
| James Vizard | vizard001jam | 1903 | Ionia MI | Independent | , | ||
| Oscar Vogeding | 1903 | +5/23+ | Camden NJ | Independent | , | ||
| Jim Vollendorf | vollen001ado | 1903 | 5/1-9/13 | Milwaukee Creams | Western League | , | |
| Jake Volz | volz--001jac | 1903 | 4/28-7/16 | St. Paul Saints | American Association | , | |
| Jake Volz | volz--001jac | 1903 | 7/30-9/20 | Indianapolis Indians | American Association | , | |
| Cy Vorhees | vorhee001hen | 1903 | 5/2-6/3 | Baltimore Orioles | Eastern League | , | |
| Cy Vorhees | vorhee001hen | 1903 | 6/29-9/11 | Nashua | New England League | , | |
| Cy Vorhees | vorhee001hen | 1903 | 9/22 | Buffalo Bisons | Eastern League | , | |
| Bobby Vorpagel | vorpag001rob | 1903 | 4/30-5/17 | South Bend Greens | Central League | , | |
| Bobby Vorpagel | vorpag001rob | 1903 | +7/10-8/9+ | Ionia MI | Independent | , | |
| Rip Vowinkel | vowink001joh | 1903 | New London Whalers | Connecticut League | , | ||
| Rip Vowinkel | vowink001joh | 1903 | 8/27-9/19 | Utica Pent-Ups | New York State League | , | |
| Joseph Vyskocil | vyskoc001jos | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, | ||
| Joseph Vyskocil | vyskoc001jos | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| Rube Waddell | waddel001geo | 1903 | Philadelphia | American League | Philadelphia, PA | ||
| Ernie Wade | wade--002ern | 1903 | 5/1-9/8 | Holyoke Paperweights | Connecticut League | , | |
| Wageman | 1903 | Duluth Cardinals | Northern League | , | |||
| Louis Waggner | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |||
| Wagman | 1903 | Hibbling | Independent | , | |||
| Wagman | 1903 | 6/19-6/20 | Duluth Cardinals | Northern League | , | ||
| Wagner | wagner063--- | 1903 | 5/28-6/5 | Terre Haute Hottentots | Central League | , | |
| Butts Wagner | wagner001but | 1903 | 4/30-9/26 | Providence Grays | Eastern League | , | |
| Don Wagner | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |||
| Heinie Wagner | wagner001cha | 1903 | 4/30-9/26 | Newark Sailors | Eastern League | , | |
| Ivor Wagner | wagner001ivo | 1903 | 4/24-9/20 | Columbus Senators | American Association | , | |
| John Wagner | wagner001joh | 1903 | 47 g. | Dubuque Shamrocks | Illinois-Indiana-Iowa League | , | |
| John Wagner | wagner001joh | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Spri, | ||
| Carl Wahler | wahler000car | 1903 | 8/7-8/23 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Valentine Wahler | wahler000val | 1903 | 7/27-9/2 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Dit Wakefield | wakefi001hen | 1903 | 6/17,94-9/8 | Springfield Midgets | Missouri Valley League | , | |
| Dit Wakefield | wakefi001hen | 1903 | +9/12+ | Spri.-Garnett | Independent | , | |
| Irv Waldron | waldro001irv | 1903 | 4/28-9/17 | Kansas City Blue Stockings | Western League | , | |
| Frank Wales | wales-000fra | 1903 | no g. | Dayton Veterans | Central League | , | |
| Frank Wales | wales-000fra | 1903 | Tiffin OH | Independent | , | ||
| Frank Wales | wales-000fra | 1903 | 7/8 | Toledo Mud Hens | American Association | , | |
| Ed Walker | walker001edw | 1903 | -6/21 | 3 g. | Cleveland | American League | Cleveland, OH |
| Ed Walker | walker001edw | 1903 | 7/11-9/9 | Toledo Mud Hens | American Association | , | |
| J. Walker | 1903 | 2 g. | Mobile | Interstate League | , | ||
| Tom Walker | walker006tho | 1903 | 4/22-9/18 | Louisville Colonels | American Association | , | |
| Joe Wall | wall--005jos | 1903 | 4/28-6/21 | Peoria Distillers | Western League | , | |
| Joe Wall | wall--005jos | 1903 | 7/14-7/18 | Utica Pent-Ups | New York State League | , | |
| Joe Wall | wall--005jos | 1903 | 7/20-9/20 | Troy Trojans | New York State League | , | |
| Wallace | 1903 | Decatur AL | Independent | , | |||
| Wallace | wallac032--- | 1903 | 7/1-7/2 | Hartford Senators | Connecticut League | , | |
| Wallace | wallac047--- | 1903 | -8/20 | Umpire | Tennessee-Alabama League | , | |
| Wallace | wallac047--- | 1903 | 8/21+ | 2 g. | Pulaski | Tennessee-Alabama League | , |
| Arthur Wallace | wallac001art | 1903 | 6 g. | Brewton | Interstate League | , | |
| Arthur Wallace | wallac001art | 1903 | Mobile | Interstate League | , | ||
| Arthur Wallace | wallac001art | 1903 | Biloxi MS | Independent | , | ||
| C. Wallace | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |||
| Harry Wallace | wallac003har | 1903 | 9/2-9/9 | Evansville River Rats | Central League | , | |
| Robert Wallace | wallac001rob | 1903 | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | ||
| E. H. Waller | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |||
| Red Waller | waller001joh | 1903 | Harrisburg PA | Independent | , | ||
| Red Waller | waller001joh | 1903 | 7/4-9/3 | Bridgeport Orators | Connecticut League | , | |
| Red Waller | waller001joh | 1903 | Harrisburg PA | Independent | , | ||
| Red Waller | waller001joh | 1903 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | ||
| W. H. Wallis | wallis000wh- | 1903 | St.Charles MO | Trolley League | , | ||
| W. H. Wallis | wallis000wh- | 1903 | 5/2-5/3 | Sedalia Goldbugs | Missouri Valley League | , | |
| Ed Walsh | walsh-002edw | 1903 | 5/7-7/30 | Meriden Silverites | Connecticut League | , | |
| Ed Walsh | walsh-002edw | 1903 | 8/1-9/26 | Newark Sailors | Eastern League | , | |
| Ed Walsh | walsh-002edw | 1903 | +10/1+ | Wilkes-Barre PA | Independent | , | |
| John Walsh | walsh-006joh | 1903 | 6/22 | Philadelphia | National League | Philadelphia, PA | |
| Joseph Walsh | walsh-009jos | 1903 | Seattle | , | |||
| Mickey Walsh | walsh-008mic | 1903 | 8/21-8/24 | Hartford Senators | Connecticut League | , | |
| Mickey? Walsh | walsh-072--- | 1903 | 7/3 | Hartford Senators | Connecticut League | , | |
| Pete Walsh | walsh-001pet | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Pete Walsh | walsh-001pet | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| William Walsh | walsh-001wil | 1903 | Kingston Colonials | Hudson River League | , | ||
| William Walsh | walsh-001wil | 1903 | Saugerties | Hudson River League | , | ||
| Walter | walter042--- | 1903 | 8/21-8/24 | Hartford Senators | Connecticut League | , | |
| Clyde Walters | walter001cly | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Clyde Walters | walter001cly | 1903 | 8/21+ | Columbia | Tennessee-Alabama League | , | |
| Daniel Walters | walter003d-- | 1903 | 7/21 | Atlanta Crackers | Southern Association | , | |
| Daniel Walters | walter003d-- | 1903 | 3-9 | Monroe Hill Citys | Cotton States League | , | |
| Henry Walters | walter001hen | 1903 | 112 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Jack Walters | walter001joh | 1903 | 4/14-8/19 | Los Angeles | Pacific National League | , | |
| Jack Walters | walter001joh | 1903 | Oakland Reliance | California State League | , | ||
| Jack Walters | walter001joh | 1903 | Stockton | California State League | , | ||
| Lew Walters | walter001lew | 1903 | 4/30-6/16 | Terre Haute Hottentots | Central League | , | |
| Lew Walters | walter001lew | 1903 | 2 g. | Oakland Oaks | Pacific Coast League | , | |
| Lew Walters | walter002lew | 1903 | 7/15 | Indianapolis Indians | American Association | , | |
| Roxey Walters | walter001lou | 1903 | 89 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Roxey Walters | walter001lou | 1903 | Rockford Red Sox | Illinois-Indiana-Iowa League | , | ||
| Roxey Walters | walter001lou | 1903 | 9/8-9/10 | Milwaukee Brewers | American Association | , | |
| Wanek | wanek-000--- | 1903 | 6/16-7/16 | Giltner | Central Nebraska League | , | |
| Ward | 1903 | +5/8+ | Creston IA | Independent | , | ||
| Ward | 1903 | +7/11-8/8+ | Creston Cyclones | Southwest Iowa League | , | ||
| Ward | 1903 | +8/21+ | Osceola | Southwest Iowa League | , | ||
| Myles Ward | ward--001myl | 1903 | 5/2-5/16 | Fall River Indians | New England League | , | |
| Piggy Ward | ward--002fra | 1903 | 4/14-10/4 | Butte Miners | Pacific National League | , | |
| Rube Ward | ward--003joh | 1903 | 4/24-5/8 | Helena Senators | Pacific National League | , | |
| Rube Ward | ward--003joh | 1903 | 59 g. | Seattle Siwashes | Pacific Coast League | , | |
| William Ward | 1903 | 5/1-5/9 | Brockton/New Bedford Whalers | New England League | Brockton, | ||
| Al Warner | warner002al- | 1903 | 4/14- | Umpire | Pacific National League | , | |
| Bobby Warner | warner002rob | 1903 | 5/21-8/13+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Charles Warner | warner014--- | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Jack Warner | warner002joh | 1903 | 89 g. | New York | National League | New York, NY | |
| Sam Warner | warner000sam | 1903 | 8/8-8/11+ | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Sam Warner | warner000sam | 1903 | Weir City KS | Independent | , | ||
| Warren | warren025--- | 1903 | 9/10 | Hartford Senators | Connecticut League | , | |
| Wally Warren | warren002wal | 1903 | 5/1-9/12 | Fall River Indians | New England League | , | |
| Mum Warrender | warren002fra | 1903 | 5/1-5/29 | Anderson/Grand Rapids Orphans | Central League | Anderson, | |
| Mum Warrender | warren002fra | 1903 | 5/30-9/12 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Libe Washburn | washbu001lib | 1903 | -7/17 | 8 g. | Philadelphia | National League | Philadelphia, PA |
| Libe Washburn | washbu001lib | 1903 | 9/7 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Buck Washer | washer001wil | 1903 | 5/6-5/13 | Wheeling Stogies | Central League | , | |
| Buck Washer | washer001wil | 1903 | Homestead PA | Independent | , | ||
| Frank Waterbury | waterb001fra | 1903 | Oakland Heeseman | California State League | , | ||
| Frank Waterbury | waterb001fra | 1903 | +4/29+ | San Francisco Pirates | Pacific National League | , | |
| Frank Waterbury | waterb001fra | 1903 | +4/29+ | San Francisco Pirates | Pacific National League | , | |
| Emmitt Waters | waters001emm | 1903 | Los Angeles Angels | Pacific Coast League | , | ||
| William Waters | 1903 | Eureka | Humboldt | , | |||
| Bill Watkins | watkin002bil | 1903 | 4/22-9/21 | Indianapolis Indians | American Association | , | |
| Watson | 1903 | Williams Col. | College | , | |||
| Watson | 1903 | Blakinton MA | Independent | , | |||
| Frank Watson | watson003fra | 1903 | 5/17- | Sault Ste. Marie | Independent | , | |
| Lanos Watson | watson001lan | 1903 | 5/14-7/18 | Beaumont Oil Gushers | South Texas League | , | |
| Scott Watson | 1903 | Reading YMCA | Independent | , | |||
| George Watt | watt--001geo | 1903 | 4/25-9/18 | Little Rock Travelers | Southern Association | , | |
| Adolph Wattrick | wattri001e-- | 1903 | +7/29+ | Bellaire MI | Independent | , | |
| Al Watts | watts-001al- | 1903 | 5/7- | Concord Marines | New England League | , | |
| Al Watts | watts-001al- | 1903 | -5/21 | Fall River Indians | New England League | , | |
| Michael Watts | 1903 | Tiflin OH | Independent | , | |||
| Michael Watts | 1903 | Findlay OH | Independent | , | |||
| Oscar Way | way---001osc | 1903 | Marion Oilworkers | Central League | , | ||
| Dick Weand | weand-001geo | 1903 | Pottstown PA | Independent | , | ||
| Weaver | weaver032--- | 1903 | 7/11-7/23 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Weaver | weaver036--- | 1903 | +8/23-9/4+ | Columbia | Tennessee-Alabama League | , | |
| Weaver | weaver035--- | 1903 | +8/14-9/10 | Pulaski | Tennessee-Alabama League | , | |
| Art Weaver | weaver001art | 1903 | 16 g. | St. Louis | National League | St. Louis, MO | |
| Art Weaver | weaver001art | 1903 | 16 g. | Pittsburgh | National League | Pittsburgh, PA | |
| Farmer Weaver | weaver001far | 1903 | 4/14-8/20 | San Francisco Pirates | Pacific National League | , | |
| Farmer Weaver | weaver001far | 1903 | -10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Fred Weaver | weaver001fre | 1903 | 108 g. | Monroe Hill Citys | Cotton States League | , | |
| John Weaver | weaver003joh | 1903 | 5/8-9/12 | Utica Pent-Ups | New York State League | , | |
| Fred Webber | webber001fre | 1903 | 5/1- | Brockton/New Bedford Whalers | New England League | Brockton, | |
| Fred Webber | webber001fre | 1903 | -5/27 | Lowell Tigers | New England League | , | |
| Peter Webber | webber001pet | 1903 | 5/21-9/16 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | |
| Arthur Weber | weber-001art | 1903 | 4/25-8/30 | Houston Buffaloes | South Texas League | , | |
| Charlie Weber | weber-003cha | 1903 | 4/25-8/10 | Beaumont Oil Gushers | South Texas League | , | |
| Edward Webster | webste003edw | 1903 | 8/3-8/14 | Umpire | New England League | , | |
| Edward Webster | webste001edw | 1903 | 4/28-9/17 | Kansas City Blue Stockings | Western League | , | |
| Al Weddige | weddig001alb | 1903 | 5/1-9/12 | Fall River Indians | New England League | , | |
| Fred Weed | weed--001fre | 1903 | 4/14- | 128 g. | San Francisco Pirates | Pacific National League | , |
| Fred Weed | weed--001fre | 1903 | +7/17+ | Spokane Indians | Pacific National League | , | |
| Fred Weed | weed--001fre | 1903 | +7/22-8/28+ | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake City, | |
| Bert Weeden | weeden001cha | 1903 | 5/7-5/9 | New Haven Blues | Connecticut League | , | |
| Bert Weeden | weeden001cha | 1903 | 5/15-6/1 | Holyoke Paperweights | Connecticut League | , | |
| Bert Weeden | weeden001cha | 1903 | Claremont NH | Independent | , | ||
| Tom Weeks | 1903 | , | |||||
| Walter Weeks | weeks-001w-- | 1903 | 4/28-7/30 | Kansas City Blue Stockings | Western League | , | |
| William Weida | weida-000wil | 1903 | +5/3+ | Cant.-Hampton | Independent | , | |
| Genser Weidensaul | weiden001yen | 1903 | 5/2-5/13 | Toronto Maple Leafs | Eastern League | , | |
| Genser Weidensaul | weiden001yen | 1903 | 5/18-6/4 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Genser Weidensaul | weiden001yen | 1903 | 6/9 | Toronto Maple Leafs | Eastern League | , | |
| Genser Weidensaul | weiden001yen | 1903 | 6/22-8/2 | Albany Senators | New York State League | , | |
| Genser Weidensaul | weiden001yen | 1903 | 8/8=9/26 | Toronto Maple Leafs | Eastern League | , | |
| Bill Weigand | weigan002wil | 1903 | 41 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| Curt Weigand | weigan001cur | 1903 | York PA | Independent | , | ||
| Curt Weigand | weigan001cur | 1903 | 6/24-6/29 | Baltimore Orioles | Eastern League | , | |
| Jacob Weihl | 1903 | 9/4 | Brockton/New Bedford Whalers | New England League | New Bedford, | ||
| Henry Weihrauch | weihra001hen | 1903 | Greenville Grays | Cotton States League | , | ||
| Frank Weikart | weiker001fra | 1903 | 4/25-9/20 | Shreveport Giants | Southern Association | , | |
| Weiland | weilan002--- | 1903 | +8/13+ | Emporia State | College | , | |
| Weiland | weilan002--- | 1903 | Lyons KS | Independent | , | ||
| Jake Weimer | weimer001jac | 1903 | 4/17- | 118 g. | Chicago | National League | Chicago, IL |
| Louis Weisbecker | weisbe001lou | 1903 | 5/7-8/31 | Meriden Silverites | Connecticut League | , | |
| Raymond Weisbrod | weisbr001j-- | 1903 | 5/6-5/15 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Raymond Weisbrod | weisbr001j-- | 1903 | Quincy IL | Independent | , | ||
| Raymond Weisbrod | weisbr001j-- | 1903 | 5/6-5/15 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Charles Weisner | weisne002cha | 1903 | +7/16-8/15 | Springfield Midgets | Missouri Valley League | , | |
| John Weisser | weisse000joh | 1903 | 7/30-7/31 | Wheeling Stogies | Central League | , | |
| Conrad Welch | welch-001con | 1903 | 8/11-9/7 | Decatur | Tennessee-Alabama League | , | |
| Harry Welch | welch-002har | 1903 | 5/16-9/17 | Omaha Indians | Western League | , | |
| Kelly Welch | welch-000kel | 1903 | 6/29-8/22+ | Creston Cyclones | Southwest Iowa League | , | |
| Mike Welday | welday001lyn | 1903 | 5/13 | Omaha Indians | Western League | , | |
| Mike Welday | welday001lyn | 1903 | 5/22-8/2+ | Joplin Miners | Missouri Valley League | , | |
| Burns Weller | weller001h-- | 1903 | +9/16+ | Mount Morris NY | Independent | , | |
| Wells | wells-017--- | 1903 | 5/7-6/14 | Dayton | Inland Empire League | , | |
| Wells | wells-017--- | 1903 | 7/26-8/9 | Centralia Midgets | Southwest Washington League | , | |
| Wells | wells-017--- | 1903 | 8/16 | Olympia Senators | Southwest Washington League | , | |
| Owen Wells | 1903 | 4/27-4/30 | Galveston Sand Crabs | South Texas League | , | ||
| Pariel Wells | wells-001par | 1903 | 4/26-5/6 | Dallas Giants | Texas League | , | |
| Welsh | 1903 | 9/10-9/12 | Utica Pent-Ups | New York State League | , | ||
| Robert Welsh | 1903 | 5/19 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | ||
| John Welter | welter002joh | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| John Welter | welter002joh | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| John Welter | welter002joh | 1903 | 9/13-9/16 | Evansville River Rats | Central League | , | |
| Fred Wenig | wenig-001fre | 1903 | - 7/17 | 54 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet/Spring, |
| Jack Wentz | wentz-001jac | 1903 | 5/13-9/16 | Wheeling Stogies | Central League | , | |
| Perry Werden | werden001per | 1903 | 4/25-9/20 | Memphis Egyptians | Southern Association | , | |
| West | 1903 | 5/9 | Newark Sailors | Eastern League | , | ||
| Tommy West | 1903 | 4/30-5/28+ | Colfax | Inland Empire League | , | ||
| Coley Westbrook | westbr002--- | 1903 | +9/7+ | Colu.-Ft Valley | Independent | , | |
| Westlake | westla004--- | 1903 | 12 g. | Providence Grays | Eastern League | , | |
| Bob Westlake | westla001rob | 1903 | 4/25-8/25 | Corsicana Oil Citys | Texas League | , | |
| Bob Westlake | westla001rob | 1903 | Chatham | , | |||
| Bob Westlake | westla004--- | 1903 | 8/8-9/25 | Providence Grays | Eastern League | , | |
| George Westlake | westla002geo | 1903 | Umpire | Texas League | , | ||
| Charles Weston | 1903 | 6/16-7/31 | Umpire | New York State League | , | ||
| Gus Weyhing | weyhin001aug | 1903 | 4/29-8/25 | Atlanta Crackers | Southern Association | , | |
| Gus Weyhing | weyhin001aug | 1903 | 9/5-9/17 | Little Rock Travelers | Southern Association | , | |
| Jimmy Whalen | whalen003wil | 1903 | 59 g. | San Francisco Seals | Pacific Coast League | , | |
| Robert Whalen | whalen001rob | 1903 | 1 g. | Oakland Oaks | Pacific Coast League | , | |
| Tom Whealon | whealo001tho | 1903 | 4/30-5/5 | Terre Haute Hottentots | Central League | , | |
| Tom Whealon | whealo001tho | 1903 | 5/20-5/26 | Duluth Cardinals | Northern League | , | |
| Tom Whealon | whealo001tho | 1903 | 6/18-6/23 | Fargo | Northern League | , | |
| Tom Whealon | whealo001tho | 1903 | York ND | Independent | , | ||
| J. Frank Wheatley | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | |||
| Wheeler | 1903 | 7/18-8/18 | Rochester Bronchos | Eastern League | , | ||
| Charles Wheeler | wheele004cha | 1903 | 3 g. | Mobile | Interstate League | , | |
| Charles Wheeler | wheele004cha | 1903 | Brewton | Interstate League | , | ||
| Ed Wheeler | wheele003edw | 1903 | 4/22-9/21 | St. Paul Saints | American Association | , | |
| George Wheeler | wheele002geo | 1903 | 198 g. | Los Angeles Angels | Pacific Coast League | , | |
| George Whisner | whisne001geo | 1903 | Jamestown NY | , | |||
| George Whisner | whisne001geo | 1903 | Warren OH | Independent | , | ||
| Lew Whistler | whistl002lew | 1903 | 4/27-9/4 | Montgomery Black Sox | Southern Association | , | |
| John Whitaker | whitak001j-- | 1903 | +9/6-9/8+ | Pulaski | Tennessee-Alabama League | , | |
| Whitcomb | whitco005--- | 1903 | +6/24+ | Giltner | Central Nebraska League | , | |
| Whitcomb | whitco005--- | 1903 | 6/-7/24 | Red Cloud | Central Nebraska League | , | |
| White | white-055--- | 1903 | 5/30-7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbC, | |
| White | white-134--- | 1903 | 7/7-7/11+ | Joplin Miners | Missouri Valley League | , | |
| White | white-138--- | 1903 | +6/13-7/24 | Minden | Central Nebraska League | , | |
| Doc White | white-001guy | 1903 | Chicago | American League | Chicago, IL | ||
| Foley White | white-001fol | 1903 | 4/29-5/10 | Beaumont Oil Gushers | South Texas League | , | |
| George White | white-006geo | 1903 | Roseburg | Willamette Valley | Roseburg, OR | ||
| Harry White | white-007har | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Harry White | white-007har | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Harry White | white-009har | 1903 | 4/22-9/20 | Louisville Colonels | American Association | , | |
| Harvey White | 1903 | +6/11+ | Muskegon MI | Independent | , | ||
| Jack White | white-012joh | 1903 | 4/30-9/24 | Toronto Maple Leafs | Eastern League | , | |
| Robert White | white-010rob | 1903 | 4/27-9/19 | Shreveport Giants | Southern Association | , | |
| Roy White | white-004roy | 1903 | +8/12-8/28+ | Tampa FL | Independent | , | |
| William White | white-024wil | 1903 | 5/2-9/27 | Sedalia Goldbugs | Missouri Valley League | , | |
| William White | white-005w-- | 1903 | 5/25-7/10 | Crookston Crooks | Northern League | , | |
| William White | white-005w-- | 1903 | +7/20-8/14+ | Fargo | Northern League | , | |
| William White | 1903 | U. of Pennsylv. | College | , | |||
| William White | 1903 | no g. | Rochester Bronchos | Eastern League | , | ||
| Whitfield | 1903 | 4/30-6/4+ | Dayton | Inland Empire League | , | ||
| Hobart Whiting | 1903 | 6/1-6/3 | Brockton/New Bedford Whalers | New England League | Brockton, | ||
| Jesse Whiting | whitin002jes | 1903 | 5/1-9/12 | Manchester | New England League | , | |
| Whitmore | whitmo004--- | 1903 | 7/25-7/26 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| H. M.? Whitney | whitne012--- | 1903 | +8/3-8/14+ | Los Angeles | Pacific National League | , | |
| Merle Whitney | whitne001mer | 1903 | Addison NY | Independent | , | ||
| Merle Whitney | whitne001mer | 1903 | 9/2-9/20 | Utica Pent-Ups | New York State League | , | |
| Al Whitridge | whitri001alb | 1903 | 4/30-9/17 | Denver Grizzlies | Western League | , | |
| Bob Wicker | wicker001rob | 1903 | 1 g. | St. Louis | National League | St. Louis, MO | |
| Bob Wicker | wicker001rob | 1903 | 32 g. | Chicago | National League | Chicago, IL | |
| C.W. Wickizer | wickhe001c-- | 1903 | 5/15-6/30 | Joplin Miners | Missouri Valley League | , | |
| Jimmy Wiggs | wiggs-001jam | 1903 | 4/23- | 2 g. | Cincinnati | National League | Cincinnati, OH |
| Jimmy Wiggs | wiggs-001jam | 1903 | 5/13-5/29 | San Francisco Pirates | Pacific National League | , | |
| Jimmy Wiggs | wiggs-001jam | 1903 | 6/11-7/17+ | Helena Senators | Pacific National League | , | |
| Jimmy Wiggs | wiggs-001jam | 1903 | +8/2-10/4 | Portland Green Gages/Salt Lake City Elders | Pacific National League | Salt Lake, | |
| Shanks Wilbur | wilbur000sha | 1903-06 | Syracuse Univ. | College | , | ||
| Shanks Wilbur | wilbur000sha | 1903 | St. Alban | Vermont League | , | ||
| Percy Wilder | wilder001per | 1903 | Benton Harbor MI | Independent | , | ||
| Percy Wilder | wilder001per | 1903 | 10 g. | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |
| Jack Wiley | wiley-001joh | 1903 | 5/1- | Lawrence Colts | New England League | , | |
| Jack Wiley | wiley-001joh | 1903 | -9/12 | Concord Marines | New England League | , | |
| Harry Wilhelm | wilhel002har | 1903 | 5/8-6/18 | Albany Senators | New York State League | , | |
| Harry Wilhelm | wilhel002har | 1903 | York-PennPark | Independent | , | ||
| Irvin Wilhelm | wilhel001irv | 1903 | 13 g. | Pittsburgh | National League | Pittsburgh, PA | |
| Joseph Wilkes | wilkes001jos | 1903 | 6/26-9/8 | Duluth Cardinals | Northern League | , | |
| Joe Wilkins | wilkin001jos | 1903 | +4/7-5/26+ | Yakima WA | Independent | , | |
| Joe Wilkins | wilkin001jos | 1903 | Pendelton | Inland Empire League | , | ||
| Roy Wilkins | wilkin001roy | 1903 | Ft. Scott HS | High School | , | ||
| Roy Wilkins | wilkin001roy | 1903 | Wichita KS | Independent | , | ||
| Roy Wilkins | wilkin001roy | 1903 | 8/11 | Fort Scott Giants | Missouri Valley League | , | |
| Wilkinson | wilkin025--- | 1903 | 6/12+ | Pittsburg Coal Diggers | Missouri Valley League | , | |
| George Wilkinson | wilkin003geo | 1903 | 4/30-7/30 | Marion Oilworkers | Central League | , | |
| George Wilkinson | wilkin003geo | 1903 | 8/1-9/16 | Terre Haute Hottentots | Central League | , | |
| Jack Wilkinson | wilkin004jac | 1903 | 6/30-7/1 | Marion Oilworkers | Central League | , | |
| Walter Willard | willar001wal | 1903 | 5/14-7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Nevada/WebbC, | |
| Williams | willia308--- | 1903 | 5/7-6/24 | Hartford Senators | Connecticut League | , | |
| Williams | willia343--- | 1903 | +5/8+ | Joplin Miners | Missouri Valley League | , | |
| Williams | willia067--- | 1903 | +9/4-9/8 | Superior Longshoremen | Northern League | , | |
| Alfred Williams | willia001alf | 1903 | Newburgh Taylor-mades | Hudson River League | , | ||
| Art Williams | willia002art | 1903 | 5/8-9/20 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| Clyde Williams | willia002s-- | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| Clyde Williams | willia002s-- | 1903 | 54 g. | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Clyde Williams | 1903 | Spokane Indians | Pacific National League | , | |||
| Dal Williams | willia001lev | 1903 | 43 g. | Davenport River Rats | Illinois-Indiana-Iowa League | , | |
| Dave Williams | willia013dav | 1903 | 4/28-6/26 | Columbus Senators | American Association | , | |
| Dave Williams | willia013dav | 1903 | 52 g. | Altoona PA | Independent | , | |
| David Williams | willia011dav | 1903 | 9/13-9/14 | Evansville River Rats | Central League | , | |
| Jimmy Williams | willia025jam | 1903 | New York | American League | New York, NY | ||
| Kid Williams | willia003kid | 1903 | Walla Walla WA | Independent | , | ||
| Kid Williams | willia003kid | 1903 | 4/30-6/14 | Dayton | Inland Empire League | , | |
| Kid Williams | willia003kid | 1903 | Everett WA | Independent | , | ||
| Kid Williams | 1903 | Altoona PA | Independent | , | |||
| Nick Williams | willia122--- | 1903 | Oakland Reliance | California State League | , | ||
| Nick Williams | willia011ric | 1903 | 7/4-9/20 | Minneapolis Millers | American Association | , | |
| Otto Williams | willia001ott | 1903 | 53 g. | St. Louis | National League | St. Louis, MO | |
| Otto Williams | willia001ott | 1903 | 38 g. | Chicago | National League | Chicago, IL | |
| Pop Williams | willia008wal | 1903 | Chicago | National League | Chicago, IL | ||
| Pop Williams | willia008wal | 1903 | Philadelphia | National League | Philadelphia, PA | ||
| Pop Williams | willia008wal | 1903 | Boston | National League | Boston, MA | ||
| Ski Williams | 1903 | 4/30-6/14 | Dayton | Inland Empire League | , | ||
| Ski Williams | 1903 | +6/21+ | Walla Walla WA | Independent | , | ||
| Ski Williams | 1903 | 4/30-6/14 | Dayton | Inland Empire League | , | ||
| Tom Williams | willia004tom | 1903 | 4/22-9/11 | Indianapolis Indians | American Association | , | |
| Williamson | 1903 | 8/11 | Winnipeg Maroons | Northern League | , | ||
| Henry Williamson | 1903 | 8/5-8/7 | New Orleans Pelicans | Southern Association | , | ||
| Emile Williford | 1903 | U. S. Army | , | ||||
| Louie Willig | willig001lou | 1903 | +8/18+ | Williamsport PA | Independent | , | |
| Willingham | 1903 | +7/5+ | Dallas-Steers | Amateur | , | ||
| Willis | 1903 | +7/12+ | Chillicothe OH | Independent | , | ||
| Willis | willis026--- | 1903 | 9/6 | Terre Haute Hottentots | Central League | , | |
| David Willis | willis024--- | 1903 | 5/27-6/10+ | 15 g. | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Joliet, |
| David Willis | willis024--- | 1903 | Joliet Standards/Springfield Foot Trackers | Illinois-Indiana-Iowa League | Springfield, | ||
| Delaware Willis | willis001del | 1903 | 4/30-9/14 | Evansville River Rats | Central League | , | |
| Frank Willis | willis001fra | 1903 | St. Johns NB | Independent | , | ||
| Frank Willis | willis001fra | 1903 | 8/2-8/22 | Syracuse Stars | New York State League | , | |
| Frank Willis | willis001fra | 1903 | 9/7-9/20 | Ilion Typewriters | New York State League | , | |
| Vic Willis | willis001vic | 1903 | Boston | National League | Boston, MA | ||
| Fred Wills | wills-001cha | 1903 | 5/15 | Dallas Giants | Texas League | , | |
| Albert Wilmot | wilmot001alb | 1903 | 9/2 | Columbus Senators | American Association | , | |
| Walt Wilmot | wilmot001wal | 1903 | 4/22-5/7 | Minneapolis Millers | American Association | , | |
| Walt Wilmot | wilmot001wal | 1903 | 5/21-10/4 | Butte Miners | Pacific National League | , | |
| Robert Wilner | willne001rob | 1903 | Idaho State League | , | |||
| Robert Wilner | willne001rob | 1903 | +6/4+ | Pendleton | Inland Empire League | , | |
| Wilson | wilson155--- | 1903 | Davenport River Rats | Illinois-Indiana-Iowa League | , | ||
| Wilson | wilson051--- | 1903 | +7/27-8/5+ | Duluth Cardinals | Northern League | , | |
| Wilson | 1903 | +7/27+ | St. Cloud MN | Independent | , | ||
| Wilson | 1903 | 6/4 | Baltimore Orioles | Eastern League | , | ||
| Wilson | wilson192--- | 1903 | 6/8-7/24 | McCook | Central Nebraska League | , | |
| Artie Wilson | wilson005art | 1903 | 5/2-9/27 | Iola Gaslighters | Missouri Valley League | , | |
| Bill Wilson | wilson003bil | 1903 | 4/28-9/11 | Peoria Distillers | Western League | , | |
| C. Wilson | 1903 | Owensboro Distillers | Kentucky-Illinois-Tennessee League | , | |||
| E. H. Wilson | wilson000eh- | 1903 | 5/27-6/10 | Leavenworth White Sox | Missouri Valley League | , | |
| Ernest Wilson | wilson001ern | 1903 | College | , | |||
| Ernest Wilson | wilson001ern | 1903 | +10/1+ | Eskr.-McFarland | Independent | , | |
| Gary Wilson | wilson010jam | 1903 | 5/1-9/12 | Nashua | New England League | , | |
| Gary Wilson | wilson010jam | 1903 | 9/14-9/20 | Utica Pent-Ups | New York State League | , | |
| Howard Wilson | wilson001how | 1903 | Washington | American League | Washington, DC | ||
| Parke Wilson | wilson001par | 1903 | 75 g. | Seattle Siwashes | Pacific Coast League | , | |
| S. A. Wilson | wilson002s-- | 1903 | 6/30-7/13 | Galveston Sand Crabs | South Texas League | , | |
| Willis Wilson | wilson025wil | 1903 | 4/15- | Portland Green Gages/Salt Lake City Elders | Pacific National League | Portland, | |
| Zeke Wilson | wilson002zek | 1903 | 4/27-9/19 | Atlanta Crackers | Southern Association | , | |
| Hooks Wiltse | wiltse001geo | 1903 | 5/8-9/20 | Troy Trojans | New York State League | , | |
| Lewis Wiltse | wiltse001lew | 1903 | 5/25-9/26 | Baltimore Orioles | Eastern League | , | |
| Lewis Wiltse | wiltse001lew | 1903 | New York | American League | New York, NY | ||
| Dolph Wind | wind--001ado | 1903 | 5/27-5/28+ | Iola Gaslighters | Missouri Valley League | , | |
| Dolph Wind | wind--001ado | 1903 | 6/23-7/16 | Leavenworth White Sox | Missouri Valley League | , | |
| Dolph Wind | wind--001ado | 1903 | 28 g. | Rock Island Islanders | Illinois-Indiana-Iowa League | , | |
| Frank Wingert | winger001fra | 1903 | 6/19-6/30 | Joplin Miners | Missouri Valley League | , | |
| Lave Winham | winham001laf | 1903 | Columbus Senators | American Association | , | ||
| Lave Winham | winham001laf | 1903 | 5/1-7/18 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Lave Winham | winham001laf | 1903 | 7/26-8/7 | Montreal Royals/Worcester Riddlers | Eastern League | Montreal, | |
| Lave Winham | winham001laf | 1903 | -9/21 | 5 g. | Pittsburgh | National League | Pittsburgh, PA |
| Lave Winham | winham001laf | 1903 | Waynesburg | Independent | , | ||
| George Winter | winter001geo | 1903 | Boston | American League | Boston, MA | ||
| George Winters | winter002geo | 1903 | 4/27-9/19 | Atlanta Crackers | Southern Association | , | |
| Scott Winters | winter002sco | 1903 | Zanesville OH | ProtAssn | , | ||
| Doc Wiseman | wisema001jul | 1903 | 4/27-8/5 | Nashville Volunteers | Southern Association | , | |
| Doc Wiseman | wisema001jul | 1903 | 8/11-9/20 | New Orleans Pelicans | Southern Association | , | |
| George Witbeck | witbec001geo | 1903 | 5/18-7/4 | Amsterdam-Gloversville-Johnstown Hyphens | New York State League | , | |
| George Witbeck | witbec001geo | 1903 | +8/17+ | Burlington | Northern New York League | , | |
| George Witbeck | witbec001geo | 1903 | 8/24 | Baltimore Orioles | Eastern League | , | |
| George Witbeck | witbec001geo | 1903 | 9/3-9/7 | Ilion Typewriters | New York State League | , | |
| Al Withoff | withof001al- | 1903 | 8/21-9/5 | Dayton Veterans | Central League | , | |
| Harvey Witt | witt--002har | 1903 | +6/23-7/26+ | Cairo Egyptians | Kentucky-Illinois-Tennessee League | , | |
| Harvey Witt | witt--002har | 1903 | +9/4+ | Paducah Chiefs | Kentucky-Illinois-Tennessee League | , | |
| Anthony Wittkow | wittko001ant | 1903 | 18 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , | |
| W. Wohlschlager | wohlsc000w-- | 1903 | 7/16 | Meriden Silverites | Connecticut League | , | |
| W. Wohlschlager | wohlsc000w-- | 1903 | 8/10-9/3 | Hartford Senators | Connecticut League | , | |
| Wolfe | wolfe-023--- | 1903 | 6/8-6/9 | Anderson/Grand Rapids Orphans | Central League | Grand Rapids, | |
| Barney Wolfe | wolfe-001wil | 1903 | 4/24- | 20 g. | New York | American League | New York, NY |
| Maurice Wolfe | wolfe-001mau | 1903 | 4/26-5/6 | Columbus Senators | American Association | , | |
| Maurice Wolfe | wolfe-001mau | 1903 | 5/13-9/2 | Toronto Maple Leafs | Eastern League | , | |
| Orville Wolfe | 1903 | Mathews IN | Independent | , | |||
| Roland Wolfe | wolfe-001rol | 1903 | 4/26-6/25 | Paris Parasites/Waco Steers | Texas League | Paris, | |
| Roland Wolfe | wolfe-001rol | 1903 | 6/26-8/26 | Paris Parasites/Waco Steers | Texas League | Waco, | |
| Bill Wolff | wolfe-004wil | 1903 | 5/16-6/10 | Peoria Distillers | Western League | , | |
| G. A. Wolff | 1903 | 5/1-5/9 | Fall River Indians | New England League | , | ||
| Theobald Wolff | wolff-001the | 1903 | 6/24-7/13 | Galveston Sand Crabs | South Texas League | , | |
| Harry Wolverton | wolver001har | 1903 | 123 g. | Philadelphia | National League | Philadelphia, PA | |
| John Womack | womack001har | 1903 | 7/11-7/13 | Leavenworth White Sox | Missouri Valley League | , | |
| Louis Womble | womble001lou | 1903 | +5/1+ | 10 g. | Brewton | Interstate League | , |
| Wood | 1903 | 6/19, 7/14 | Little Rock Travelers | Southern Association | , | ||
| Wood | wood--001har | 1903 | 6/23-7/5 | Birmingham Barons | Southern Association | , | |
| Bob Wood | wood--005rob | 1903 | 4/22-9/21 | Milwaukee Brewers | American Association | , | |
| Carl Wood | wood--001car | 1903 | 5/2-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Harry Wood | wood--001har | 1903 | 4/19- | 2 g. | Cincinnati | National League | Cincinnati, OH |
| Harry Wood | wood--001har | 1903 | 5/29-6/6 | Baltimore Orioles | Eastern League | , | |
| Harry Wood | wood--001har | 1903 | 6/23-7/5 | Birmingham Barons | Southern Association | , | |
| Roy Woodbury | woodbu001roy | 1903 | 5/3-9/5 | Fort Scott Giants | Missouri Valley League | , | |
| Roy Woodbury | woodbu001roy | 1903 | 9/9-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Mike Woodlock | woodlo001mic | 1903 | +7/5+ | Alton IL Blues | Independent | , | |
| Pete Woodruff | woodru002pet | 1903 | 5/8-5/30 | Holyoke Paperweights | Connecticut League | , | |
| Pete Woodruff | woodru002pet | 1903 | 6/25-7/14 | Holyoke Paperweights | Connecticut League | , | |
| Sam Woodruff | woodru001orv | 1903 | 5/1-9/20 | Indianapolis Indians | American Association | , | |
| Walt Woods | woods-002wal | 1903 | 5/2-9/26 | Jersey City Skeeters | Eastern League | , | |
| Frank Wooliver | wooliv001fra | 1903 | 5/2-6/19+ | Joplin Miners | Missouri Valley League | , | |
| Frank Wooliver | wooliv001fra | 1903 | +7/16 | Nevada Lunatics/Webb City Goldbugs | Missouri Valley League | Webb City, | |
| C. Woolridge | woolri000c-- | 1903 | Clev.-semi-pro | Independent | , | ||
| Lloyd Wooten | wooten000llo | 1903 | +4/2+ | Trinity College | College | , | |
| Lloyd Wooten | wooten000llo | 1903 | 6/12-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Lloyd Wooten | wooten000llo | 1903 | +8/14+ | Anniston AL | Independent | , | |
| Waddill Worsham | worsha000wad | 1903 | +6/23+ | Durant IT | Independent | , | |
| Worth | worth-005--- | 1903 | 8/27 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Samuel Wray | 1903 | Denton AC TX | Independent | , | |||
| Forrest Wright | wright001for | 1903 | Greenville Grays | Cotton States League | , | ||
| Forrest Wright | wright001for | 1903 | Henderson Blue Birds | Kentucky-Illinois-Tennessee League | , | ||
| Gene Wright | wright001cla | 1903 | 15 g. | Cleveland | American League | Cleveland, OH | |
| Gene Wright | wright001cla | 1903 | 8 g. | St. Louis | American League | St. Louis, MO | |
| Lucky Wright | wright007wil | 1903 | 5/10-5/22 | Corsicana Oil Citys | Texas League | , | |
| Lucky Wright | wright007wil | 1903 | 5/24-7/15 | San Antonio Bronchos | South Texas League | , | |
| Lucky Wright | wright007wil | 1903 | 7/16-7/30 | Beaumont Oil Gushers | South Texas League | , | |
| Lucky Wright | wright007wil | 1903 | 8/6-8/30 | San Antonio Bronchos | South Texas League | , | |
| Lucky Wright | wright015wil | 1903 | - 8/27 | 51 g. | Decatur Commodores | Illinois-Indiana-Iowa League | , |
| Pat Wright | wright003pat | 1903 | 4/25-9/19 | Little Rock Travelers | Southern Association | , | |
| Red Wright | wright001jos | 1903 | 4/30-7/15 | Omaha Indians | Western League | , | |
| Red Wright | wright001jos | 1903 | 7/22-9/17 | Peoria Distillers | Western League | , | |
| Zeke Wrigley | wrigle001zek | 1903 | 4/30-6/19 | Montreal Royals/Worcester Riddlers | Eastern League | Worcester, | |
| Zeke Wrigley | wrigle001zek | 1903 | 6/22-7/4 | New Orleans Pelicans | Southern Association | , | |
| Hugh Wyatt | wyatt-006--- | 1903 | +7/6+ | Columbia | Tennessee-Alabama League | , | |
| Hugh Wyatt | wyatt-006--- | 1903 | +8/6+ | Hurstburg TN | Independent | , | |
| Charles Yager | 1903-09 | , | |||||
| Ad Yale | yale--001wil | 1903 | 5/7-9/12 | Bridgeport Orators | Connecticut League | , | |
| Hogan Yancey | yancey001hog | 1903 | Transylvania U. | College | , | ||
| Homer Yancey | yancey000hom | 1903 | 6/- | Rome Romans | Alabama-Georgia League | , | |
| Yank | yank--000--- | 1903 | 6/29 | Evansville River Rats | Central League | , | |
| Charles Yeager | yeager001cha | 1903 | Greenville Grays | Cotton States League | , | ||
| Charles Yeager | yeager001cha | 1903 | Vicksburg Hill Billies | Cotton States League | , | ||
| George Yeager | yeager001geo | 1903 | 4/22-9/21 | Minneapolis Millers | American Association | , | |
| Joe Yeager | yeager002jos | 1903 | 109 g. | Detroit | American League | Detroit, MI | |
| Joseph Yeager | 1903-07 | Fall River | New England League | , | |||
| Stan Yerkes | yerkes001sta | 1903 | 4/17 | St. Louis | National League | St. Louis, MO | |
| Stan Yerkes | yerkes001sta | 1903 | 5/5-9/26 | Providence Grays | Eastern League | , | |
| John Yoedt | 1903 | +7/30+ | Pittsburgh A. C. | Independent | , | ||
| J. Frank Yohe | 1903 | Sharon PA | Independent | , | |||
| Cecil Young | young-001cec | 1903 | +4/9+ | U. of Alabama | College | , | |
| Cecil Young | young-001cec | 1903 | 7/11-8/1 | Anniston Invincibles | Alabama-Georgia League | , | |
| Deacon Young | young-000dea | 1903 | Delphos OH | Independent | , | ||
| Deacon Young | young-000dea | 1903 | 7/19 | Fort Wayne Railroaders | Central League | , | |
| Elmer Young | young-001elm | 1903 | Coatesville PA | Independent | , | ||
| Elmer Young | young-001elm | 1903 | Trenton NJ | Independent | , | ||
| Harlan Young | young-001har | 1903 | 6/16-7/5 | Pittsburg Coal Diggers | Missouri Valley League | , | |
| Irv Young | young-001irv | 1903 | 10 g. | Sacramento Senators | Pacific Coast League | , | |
| Irv Young | young-001irv | 1903 | 2 g. | Seattle Siwashes | Pacific Coast League | , | |
| Thomas Young | young-069--- | 1903 | 5/10-6/14 | Centralia Midgets | Southwest Washington League | , | |
| William Young | young-009wil | 1903 | Camden NJ | Independent | , | ||
| Henry Youngman | youngm001hen | 1903 | Dayton Veterans | Central League | , | ||
| Earnest Yount | 1903 | +4/6-4/30+ | Davidson Col | College | , | ||
| Earnest Yount | 1903 | +6/12+ | Winston NC | Independent | , | ||
| Elmer Zacher | zacher001elm | 1903 | +5/12+ | Reading PA | Independent | , | |
| Elmer Zacher | zacher001elm | 1903 | Pottstown PA | Independent | , | ||
| Elmer Zacher | zacher001elm | 1903 | Buffalo Univ. | College | , | ||
| Emil Zackert | 1903 | St. Jo.-Rex | St. Joseph City League | , | |||
| Jack Zalusky | zalusk001joh | 1903 | 4/14-8/16 | Spokane Indians | Pacific National League | , | |
| Jack Zalusky | zalusk001joh | 1903 | 9/2-9/29 | New York | American League | New York, NY | |
| G. R. Zarbaugh | zalusk000jos | 1903 | +6/7+ | Bedford | SoIa | , | |
| Dave Zearfoss | zearfo001dav | 1903 | 4/14-8/19 | San Francisco Pirates | Pacific National League | , | |
| Dave Zearfoss | zearfo001dav | 1903 | 8/27- | 50 g. | San Francisco Seals | Pacific Coast League | , |
| Louis Zehner | zehner001lou | 1903 | Monroe Hill Citys | Cotton States League | , | ||
| Louis Zehner | zehner001lou | 1903 | Baton Rouge Red Sticks | Cotton States League | , | ||
| Gus Zeimer | zeimer001gus | 1903 | 5/5-5/11 | Rochester Bronchos | Eastern League | , | |
| Gus Zeimer | zeimer001gus | 1903 | 5/17-8/13 | Schenectady Frog Alleys | New York State League | , | |
| John Zeller | zeller001j-- | 1903 | 5/10-5/25 | Joplin Miners | Missouri Valley League | , | |
| John Zeller | zeller001j-- | 1903 | 6/7 | Sedalia Goldbugs | Missouri Valley League | , | |
| John Zeller | zeller001j-- | 1903 | 6/23-7/12 | Leavenworth White Sox | Missouri Valley League | , | |
| Harry Zellers | 1903 | 5/14-5/15 | Schenectady Frog Alleys | New York State League | , | ||
| Charlie Ziegler | ziegle001cha | 1903 | 80 g. | Seattle Siwashes | Pacific Coast League | , | |
| Charlie Ziegler | ziegle001cha | 1903 | +7/17-7/29+ | Helena Senators | Pacific National League | , | |
| Kid Zieman | 1903 | 6 g. | Mobile | Interstate League | , | ||
| Bill Zink | zink--001wil | 1903 | 5/21-8/18+ | Sioux Falls Canaries | Iowa-South Dakota League | , | |
| Eddie Zinram | zinram001edw | 1903 | Natchez Indians | Cotton States League | , | ||
| Charles Zinzer | zinzer001cha | 1903 | 155 g. | Seattle Siwashes | Pacific Coast League | , | |
| Charles Zinzer | zinzer001cha | 1903 | 28 g. | Portland Browns | Pacific Coast League | , | |
| Joe Zoellers | zoelle002jos | 1903 | 8/22-9/27 | Springfield Midgets | Missouri Valley League | , | |
| Harry Zollers | zoelle001har | 1903 | 5/14-5/15 | Schenectady Frog Alleys | New York State League | , | |
| Earl Zook | zook--001ear | 1903 | 4/26-8/25 | Corsicana Oil Citys | Texas League | , | |
| August Zurlage | zurlag001a-- | 1903 | no g. | Cincinnati | National League | Cincinnati, OH | |
| August Zurlage | zurlag001a-- | 1903 | +8/15+ | Cinc.-Norwood | Independent | , |