The Bristol Blenheim is a British light bomber designed and built by the Bristol Aeroplane Company, used extensively in the first two years of the Second World War, with examples still operating as trainers until the end of the war.

Development began with the Type 142, a civil airliner, after a challenge from newspaper proprietor Lord Rothermere to produce the fastest commercial aircraft in Europe. The Type 142 first flew in April 1935, and the Air Ministry ordered a bomber development as the Type 142M for the Royal Air Force (RAF).

Deliveries of the Blenheim to RAF squadrons commenced on 10 March 1937. The Type 142M became the Blenheim Mk.I, developed into the long-nosed Blenheim Mk.IV, while in Canada Fairchild Canada built the Bolingbroke. Both versions were converted into heavy night fighters with a gun pack of four Browning .303 in machine guns. The Mk.IV also served as a maritime patrol aircraft.

The Blenheim was one of the first British aircraft with an all-metal stressed-skin construction, retractable landing gear, flaps, a powered gun turret and variable-pitch propellers. The Mk.I was faster than the RAF biplane fighters in the late 1930s, though advances soon left it outdated.