Armstrong-Siddeley Motors was formed in 1919 when Armstrong Whitworth Development Company bought Siddeley-Deasy, which had built aircraft engines during WWI. In 1935 Armstrong-Siddeley Motors became a subsidiary of Hawker Siddeley, which merged with the engine business of Bristol Aero Engines to become Bristol Siddeley in 1960, and then with Rolls-Royce in 1966.

Armstrong-Siddeley piston aircraft engines were named after big cats, most notably Puma, Lynx, Jaguar, Panther, Cheetah, Mongoose, Leopard, Genet, Serval, and Tiger. A-S Gas turbines were named after snakes and included the Mamba, Double Mamba, Python, Adder, Sapphire and Viper. Armstrong-Siddeley was also a major producer of rocket engines.