The Gloster Gladiator (or Gloster SS.37) was a British-built biplane fighter, used by the Royal Air Force (RAF) and the Royal Navy (as the Sea Gladiator variant) and was exported to a number of other air forces during the late 1930s. It was the RAF's last biplane fighter aircraft and was rendered obsolete by newer monoplane designs even as it was being introduced. Though often pitted against more formidable foes during the early days of the Second World War, it acquitted itself reasonably well in combat.
It saw action in almost all theatres during the Second World War, with a large number of air forces, some of them on the Axis side. The RAF used it in France, Norway, Greece, the defence of Malta, and the brief Anglo-Iraqi War (in which, ironically, the Royal Iraqi Air Force was similarly equipped). Other countries deploying the Gladiator included China against Japan, beginning in 1938; Finland (along with Swedish volunteers) against the Soviet Union in the Winter War and the Continuation War; and Norway, Belgium, and Greece resisting Axis invasion of their respective lands.