The Armstrong Siddeley Viper is a British turbojet engine developed and produced by Armstrong Siddeley and then by its successor companies Bristol Siddeley and Rolls-Royce Limited. It entered service in 1953 and remained in use with the Royal Air Force, powering its Dominie T1 navigation training aircraft until January 2011.

Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines.