SCAP, short for Supreme Commander Allied Powers, was the title for Douglas MacArthur during the Occupation of Japan following WWII.

SCAP also referred to the offices of the occupation, including a staff of several hundred American civil servants as well as military personnel. These personnel effectively wrote the Japan Constitution, which the Diet then ratified.

Australian, British, Indian and New Zealand forces under SCAP were organised into a sub-command known as British Commonwealth Occupation Force.

MacArthur was succeeded as SCAP by General Matthew Ridgeway when MacArthur was relieved by President Harry Truman for insubordination concerning the Korean War in April 1951. With the peace treaty with Japan, the post of SCAP lapsed.