Which Rolls-Royce engine powered the first production version of the Harrier?

The Rolls-Royce Pegasus powered the first production version of the Harrier.

The Pegasus was a turbofan engine with thrust-vectoring nozzles, allowing the Harrier to take off and land vertically or operate from very short runways. Its four rotating nozzle pairs directed engine thrust downward for vertical flight and rearward for conventional forward flight.

The first production Harrier, the Hawker Siddeley Harrier GR.1, entered Royal Air Force service in 1969 with the Pegasus 6 engine. Later Harrier variants received improved Pegasus versions with higher thrust and revised systems.

The Pegasus is sometimes confused with the Rolls-Royce Spey because both powered British military aircraft and both were developed during the jet age. The Spey powered aircraft such as the Phantom and Buccaneer, whereas the Harrier’s distinctive vertical-flight capability depended on the Pegasus and its thrust-vectoring arrangement.