The Royal Small Arms Factory ADEN cannon (ADEN being an acronym for “Armament Development, Enfield”) is a 30 mm revolver cannon used on many military aircraft, particularly those of the British Royal Air Force and Fleet Air Arm. Developed post-World War II primarily to meet British Air Ministry's requirement for increased lethality in aircraft armament, the cannon is fired electrically, and is fully automatic once loaded.

The ADEN cannon entered service on the British Hawker Hunter in 1954, and was subsequently used on every British gun-armed aircraft until the advent of the Panavia Tornado in the 1980s. The last version to see production was the Mk. 4. An improved version, the Mk. 5, incorporates a multitude of small changes to improve reliability and increase rate of fire to 1,500–1,700 rounds per minute. No new Mk 5s were built, but many older weapons were converted, being redesignated “Mk 5 Straden”.

GIAT also introduced their version of the design as the DEFA cannon; the two weapons are very similar.