| Jack Leiper | |
| Position: | Pitcher |
| Birth Date: | 23 December 1867 |
| Birth Place: | Chester, Pennsylvania |
| Death Place: | West Goshen |
| Bats: | Left |
| Throws: | Left |
| Debutleague: | MLB |
| Debutdate: | September 4 |
| Debutyear: | 1891 |
| Debutteam: | Columbus Solons |
| Finalleague: | MLB |
| Finaldate: | October 4 |
| Finalyear: | 1891 |
| Finalteam: | Columbus Solons |
| Statleague: | MLB |
| Stat1label: | Pitching record |
| Stat1value: | 2-2 |
| Stat2label: | Strikeouts |
| Stat2value: | 19 |
| Stat3label: | ERA |
| Stat3value: | 5.40 |
John Henry Thomas Leiper (1867–1960) was an American professional baseball player who played for the Columbus Solons during the season.