John Locke Mercer (January 22, 1892 – December 22, 1982) was a Major League Baseball first baseman. Mercer played in one game for the St. Louis Cardinals on June 25, 1912.
John Mercer
| Given name: | John Locke Mercer |
| Nicknames: | None |
| Primary Pos: | Firstbase |
| Hght/Wght: | 5'10" / 155 lbs |
| Bats/Throws: | L / L |
| Born: | Jan 22, 1892 in Taylortown, LA |
| Died: | Dec 22, 1982 in Shreveport, LA (90 years old) |
| Debut: | Jun 25, 1912 |