The XX Army Corps / XX AK () was a corps level command of the German Army before and during World War I. As the German Army expanded in the latter part of the 19th Century and early part of the 20th Century, the XX Army Corps was set up on 1 October 1912 in Allenstein as the Generalkommando (headquarters) for the southern part of East Prussia. It took over command of 37th Division from I Corps and the newly formed 41st Division. General der Artillerie Friedrich von Scholtz, former commander of 21st Division, took command. It was assigned to the I Army Inspectorate. which became the 8th Army at the start of the First World War.