The General Electric GAU-8/A Avenger is a 30 mm hydraulically driven seven-barrel Gatling-style autocannon that is primarily mounted in the United States Air Force's Fairchild Republic A-10 Thunderbolt II. Designed to destroy a wide variety of ground targets, the Avenger delivers very powerful rounds at a high rate of fire. The GAU-8/A is also used in the Goalkeeper CIWS ship weapon system, which provides defense against short-range threats such as highly maneuverable missiles, aircraft, and fast-maneuvering surface vessels. The GAU-8/A is produced by General Dynamics.

The 30 mm caliber is a range of autocannon ammunition. It includes the NATO standardized Swiss 30×173mm, the Soviet 30×155mmB, 30×165mm and 30×210mmB, the Czechoslovak 30×210mm, the Yugoslav 30×192mm, the British 30×113mmB, and the French 30×150mmB and 30×170mm cartridges.