No. 615 (County of Surrey) Squadron was a unit of the British Auxiliary Air Force and later the Royal Auxiliary Air Force between 1937 and 1957.

No. 615 squadron was formed at RAF Kenley as part of the Auxiliary Air Force on 1 June 1937 and was initially equipped with the Hawker Audax in the army-cooperation role. By the end of the year it had received Hawker Hectors which it flew until November 1938, when it received Gloster Gauntlets and became a fighter squadron at the same time.

The squadron went to France as part of the Air Component of the BEF in November 1939, having re-equipped with Gloster Gladiators in May. Conversion to Hawker Hurricanes took place just prior to the German invasion of France, but by 20 May 1940 the squadron was back at Kenley. "B" Flight were based at Saint Inglevert during the early part of 1940. 615 squadron took part in the early actions of the Battle of Britain, but then moved to Scotland to rest. It later took part in offensive sweeps over Europe and defence duties in Wales, before moving to India in April 1942. It moved to Burma in December 1942, but returned to India to re-equip in May 1943, receiving Supermarine Spitfires in October. It returned to operations on the Burma front in November but was recalled to India again, for defensive duties in August 1944, before returning to Burma in February 1945, disbanding there on 10 June at RAF Cuttack, Orissa. It was a very short interruption of existence as No. 135 Squadron RAF, equipped with Republic Thunderbolts was renumbered to no. 615 squadron on that same day and began training for the invasion of Malaya. The Japanese surrender ended these plans however and the squadron disbanded on 25 September 1945 at RAF Vizagapatam, Andhra Pradesh.