The de Havilland Mosquito was a British combat aircraft that excelled in versatility during the Second World War. Originally conceived as an unarmed fast bomber, the Mosquito adapted to many other roles during the air war where it saw service in the European theatre, the Pacific theatre of Operations and the Mediterranean Theatre, including: low to medium altitude daytime tactical bomber, high altitude night bomber, pathfinder, day or night fighter, fighter-bomber, intruder, maritime strike and fast photo reconnaissance aircraft carrying out aerial reconnaissance. It was also used as the basis for a single-seat heavy fighter, the de Havilland Hornet. Upon the Air Ministry's decision to enter the Mosquito into production in 1941, it was the fastest operational aircraft in the world.

Entering widespread service in 1942 the Mosquito supported RAF strategic night fighter defence forces in the United Kingdom from Luftwaffe raids, most notably defeating the German aerial offensive Operation Steinbock in 1944. Offensively the Mosquito units also conducted night time fighter sweeps in indirect and direct protection of RAF Bomber Command's bomber fleets to reduce RAF bomber losses in 1944 and 1945. The Mosquito increased German night fighter losses to such an extent the Germans were said to have awarded two victories for shooting one down.  As a bomber it also took part in "special raids", such as pinpoint attacks on Prisoner-of-war camp, Gestapo or German intelligence and security force bases as well as tactical strikes in support of the British Army in the Normandy Campaign. Some Mosquitos also saw action in RAF Coastal Command during the Battle of the Atlantic, attacking Kriegsmarine U-Boat and transport ship concentrations, particularly in the Bay of Biscay offensive in 1943 in which significant numbers of U-Boats were sunk or damaged.

The aircraft served with the Royal Air Force (RAF) and many other air forces during the Second World War and postwar. The Mosquito was known affectionately as the "Mossie" to its crews and was also known as "The Wooden Wonder" or "The Timber Terror" as the bulk of the aircraft was made of laminated plywood.