The Army Group Mackensen () which operated in Poland between 22 April 1915 and 8 September 1915 during World War I under the command of Field Marshal , was an army group of the Imperial German Army.
On 8 September 1915 it was renamed Army Group when became its new commander. In June 1916, the Army Group faced the Brusilov Offensive. After an initial retreat, it checked the Russian advance at the Battle of Kowel. After the signing of the Treaty of Brest-Litovsk in March 1918, the Army Group occupied Ukraine.
On 31 March 1918, was replaced by and the Army Group was dissolved; its troops merged into the Army Group -Kiev (). It was again renamed on 3 April to Army Group and a last time on 13 August to Army Group Kiev after the murder of General . His successor was . The Army Group was disbanded on 7 February 1919.