9 Corps, 9th Corps, Ninth Corps, or IX Corps may refer to:
France 9th Army Corps (France) IX Corps (Grande Armée), a unit of the Imperial French Army during the Napoleonic Wars
Germany IX Corps (German Empire), a unit of the Imperial German Army prior to and during World War I IX Reserve Corps (German Empire), a unit of the Imperial German Army during World War IX Army Corps (Wehrmacht), a unit in World War II IX SS Mountain Corps, a unit in World War II
Other countries IX Corps (India) IX Corps (Ottoman Empire) 9th Army Corps (Ukraine) IX Corps (United Kingdom) IX Corps (Union Army) IX Corps (United States) 9th Corps (Yugoslav Partisans)
See also List of military corps by number