15th Corps, Fifteenth Corps, or XV Corps may refer to:
- XV Corps (British India)
- XV Corps (German Empire), a unit of the Imperial German Army prior to and during World War I
- 15th Army Corps (Russian Empire), a unit in World War I
- XV Royal Bavarian Reserve Corps, a unit of the Bavarian Army and the Imperial German Army during World War I
- XV Army Corps (Wehrmacht), Germany
- XV Mountain Corps (Wehrmacht), Germany
- XV Corps (India)
- XV Corps (Ottoman Empire), a unit in World War I
- XV Corps (United States), a unit in World War II
- XV Corps (Union Army), a unit in the American Civil War
- XV Corps (United Kingdom), a unit in World War I
- 15th Rifle Corps, a Soviet unit World War II
- XV SS Cossack Cavalry Corps, a German unit in World War II
- 15th Airborne Corps, airborne corps of the Chinese Air Force
- 15th Tank Corps, tank corps of the Soviet Union's Red Army