| Birth Date: | c. 1837 |
| Death Date: | August 24, 1896 |
| Birth Place: | Clear Spring, Maryland |
| Placeofburial: | Jamaica Plains, Massachusetts |
| Allegiance: | United States of America |
| Branch: | United States Army |
| Rank: | Corporal |
| Unit: | Company F, 8th Missouri Volunteer Infantry |
| Battles: | American Civil War Battle of Vicksburg |
| Awards: | Medal of Honor |
John W. Wagner (c. 1837-August 24, 1896) was a Union Army soldier in the American Civil War who received the U.S. military's highest decoration, the Medal of Honor.
Wagner was born in Clear Spring, Maryland, and he entered service in St. Louis, Missouri. Wagner was awarded the Medal of Honor for his actions at the Battle of Vicksburg on May 22, 1863, for his gallantry in the charge of the volunteer storming party as a corporal with Company F of the 8th Missouri Infantry.
His Medal of Honor was issued on December 14, 1894, and Wagner died in 1896 and was buried in Jamaica Plains, Massachusetts.