| John Gallagher | |
| Position: | Second baseman |
| Bats: | Right |
| Throws: | Right |
| Birth Date: | February 18, 1892 |
| Birth Place: | Pittsburgh, Pennsylvania |
| Death Place: | Norfolk, Virginia |
| Debutleague: | MLB |
| Debutdate: | August 20 |
| Debutteam: | Baltimore Terrapins |
| Finalleague: | MLB |
| Finaldate: | October 3 |
| Finalteam: | Baltimore Terrapins |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .198 |
| Stat2label: | Home runs |
| Stat2value: | 0 |
| Stat3label: | Runs batted in |
| Stat3value: | 4 |
| Teams: | |
John Carroll Gallagher (February 18, 1892 – March 30, 1952) was a Major League Baseball second baseman who played for the Baltimore Terrapins of the Federal League in .