The 533d Air Defense Group is a disbanded United States Air Force organization. Its last assignment was with the 27th Air Division at Oxnard Air Force Base, California, where it was inactivated on 18 August 1955. The group was originally activated as the 533d Air Service Group, a support unit for the 483d Bombardment Group at the end of World War II in Italy.

The 27th Air Division was a United States Air Force numbered air division and the geographic Air Defense Command region controlled by the 27th AD. Its last assignment was with Air Defense Command (ADC)'s Tenth Air Force, at Luke Air Force Base, Arizona. It was inactivated on 19 November 1969.