The Saunders-Roe SR.53 was a British prototype interceptor aircraft of mixed jet and rocket propulsion developed for the Royal Air Force (RAF) by Saunders-Roe in the early 1950s. As envisaged, the SR.53 would have been used as an interceptor aircraft, using its rocket propulsion to rapidly climb and approach incoming hostile bombers at high speeds; following its attack run, the aircraft would then return to its base using jet propulsion.

An interceptor aircraft, or simply interceptor, is a type of fighter aircraft designed specifically for the defensive interception role against an attacking enemy aircraft, particularly bombers and reconnaissance aircraft. Aircraft that are capable of being or are employed as both ‘standard’ air superiority fighters and as interceptors are sometimes known as fighter-interceptors. There are two general classes of interceptor: light fighters, designed for high performance over short range; and heavy fighters, which are intended to operate over longer ranges, in contested airspace and adverse meteorological conditions. While the second type was exemplified historically by specialized night fighter and all-weather interceptor designs, the integration of mid-air refueling, satellite navigation, on-board radar and beyond visual range (BVR) missile systems since the 1960s has allowed most frontline fighter designs to fill the roles once reserved for specialised night/all-weather fighters.