The 18th Brigade was an infantry brigade of the Australian Army, which served during the Second World War. The brigade was raised on 13 October 1939 and was one of the first three infantry brigades of the Second Australian Imperial Force (2nd AIF) to be formed. Initially commanded by Brigadier Leslie Morshead, it served in the United Kingdom, the Middle East and the Pacific during the war. Following the end of hostilities, the 18th Brigade was disbanded on 3 January 1946.