Jack O'Brien (Denver Jack O'Brian) boxeador
- combates
- 7
- ganados
- 1
- perdidos
- 3
- empates
- 3
- Estado
- inactive
- División
- middleweight
- Debut
- 1919-11-26
- Altura
- -
- Alcanza
- -
- Edad
- -
- Nacimiento
- -
- Muerte
- -
- Nacionalidad
- USA
| Fecha | Oponente | Resultados últimos oponentes | Lugar | Resultado |
|---|---|---|---|---|
| 1921-09-30 | Joe Black | DLWWLD | Stockyards Stadium, Denver | WIN |
| 1921-09-09 | Harry Reide | LDDDDW | Stockyards Stadium, Denver | DRAW Points |
| 1921-06-21 | Harry Reide | WLDDLD | Stockyards Stadium, Denver | DRAW Points |
| 1921-06-03 | George Eagel | DLWWDD | Jazzland Theatre, Casper | LOST Technical knockout |
| 1921-05-20 | Billy Williams | debut | Jazzland Theatre, Casper | DRAW Points |
| 1920-01-01 | Walter Caldwell | WW | Crystal Theater, Albuquerque | LOST Technical knockout |
| 1919-11-26 | Mack Dalton | D | Salt Lake City | LOST Technical knockout |