John Gill Valentine
- Bats Unknown, Throws Unknown
- Debut May 3, 1883
- Final Game August 3, 1883
- Born November 21, 1855 in Brooklyn, NY USA
- Died October 10, 1903 in Central Islip, NY USA
John Valentine played 16 games as a pitcher/outfielder for the Columbus Buckeyes of the American Association in 1883. He had a much longer career as an umpire, working full time in the American Association from 1884 to 1887, and then in the National League in 1887 and 1888. In all, he worked 447 games, which is one of the highest totals of the 19th century.