| Home | Teams and Players | Homerun Kings | Top Salaries | Top RBI | Hall of Fame |

| Name: | Jack O'Brien |
| Given name: | John Joseph |
| Birth place: | Watervliet, NY, USA |
| Birthday: | 2/5/1873 |
| Height: | 73 inches |
| Weight: | 165 lbs |
| Batting: | Left-handed |
| Throwing: | Right-handed |
| Age/Age at time of death: | 60 |
| Year | Team Name | Batting Statistics | Pitching Statistics | Fielding Statistics |
|---|---|---|---|---|
| 1899 | Washington Senators | Hits: 118 At Bats: 439 HR: 4 RBI: 92 | Wins: 6 Losses: 4 Total Games: 12 Strikeouts: 26 Shutouts: 0 | Position: 1B Errors: 8 Double Plays: 25 Assists: 24 |
| 1901 | Cleveland Blues | Hits: 190 At Bats: 576 HR: 8 RBI: 99 | Wins: 0 Losses: 1 Total Games: 1 Strikeouts: 0 Shutouts: 0 | Position: 1B Errors: 25 Double Plays: 81 Assists: 66 |
| 1901 | Washington Senators | Hits: 190 At Bats: 576 HR: 8 RBI: 99 | Wins: 0 Losses: 1 Total Games: 1 Strikeouts: 0 Shutouts: 0 | Position: 1B Errors: 25 Double Plays: 81 Assists: 66 |
| 1903 | Boston Americans | Hits: 111 At Bats: 489 HR: 1 RBI: 46 | Wins: 0 Losses: 0 Total Games: 2 Strikeouts: 0 Shutouts: 0 | Position: 2B Errors: 45 Double Plays: 35 Assists: 325 |