Hawker Siddeley Nimrod in flight

The Nimrod is a maritime patrol aircraft developed in the United Kingdom. It is a conversion of the de Havilland Comet, the world's first jet airliner. It was originally designed by de Havilland's successor, Hawker Siddeley, but today BAE Systems is the prime contractor.

It has been the Royal Air Force's primary maritime patrol bomber since the early 1970s, when it replaced the Avro Shackleton. The RAF uses two variants: the R1 variant in a reconnaissance and electronic intelligence gathering capacity (ELINT), and the MR2 variant in the Maritime Reconnaissance role.

The Nimrod was the first jet-powered patrol aircraft. Earlier designs used piston or turboprop engines to improve fuel economy and allow for lengthy patrols. Jet engines are thirstiest at low altitudes — but the Nimrod's huge fuel capacity compensated for this. The aircraft can shut down two outboard engines at low altitude to extend endurance. It can also dash to its targets at a speed unmatched by propeller aircraft. Since the UK introduction of the Nimrod, most other new patrol designs have been jet powered, including the US Navy's S-3 Viking and future P-8.