| Leo Callahan | |
| Width: | 200 |
| Bats: | Left |
| Throws: | Left |
| Birth Date: | 9 August 1890 |
| Birth Place: | Jamaica Plain, Massachusetts, U.S. |
| Death Place: | Erie, Pennsylvania, U.S. |
| Debutleague: | MLB |
| Debutdate: | April 9 |
| Debutyear: | 1913 |
| Debutteam: | Brooklyn Dodgers |
| Finalleague: | MLB |
| Finaldate: | September 28 |
| Finalyear: | 1919 |
| Finalteam: | Philadelphia Phillies |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .221 |
| Stat2label: | Home runs |
| Stat2value: | 1 |
| Stat3label: | Runs batted in |
| Stat3value: | 12 |
| Teams: |
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Leo David Callahan (August 9, 1890 – May 2, 1982) is an American former professional baseball player who played outfield for the 1913 Brooklyn Dodgers and the 1919 Philadelphia Phillies.