13 Corps, 13th Corps, Thirteenth Corps, or XIII Corps may refer to:
- XIII Corps (Grande Armée), a unit of the Imperial French Army during the Napoleonic Wars
- XIII (Royal Württemberg) Corps, a unit of the Imperial German Army
- XIII Corps (Ottoman Empire)
- XIII Corps (United Kingdom)
- XIII Army Corps (Wehrmacht), a German unit in the Second World War
- XIII Corps (United States)
- XIII Corps (Union Army), a unit in the American Civil War