The Harrier, informally referred to as the Harrier Jump Jet, is a family of jet aircraft capable of vertical/short takeoff and landing (V/STOL) operations. Originally developed by UK manufacturer Hawker Siddeley in the 1960s, the Harrier emerged as the only truly successful V/STOL design of the many attempted during that era, despite being a subsonic aircraft, unlike most of its competitors. It was conceived to operate from improvised bases, such as car parks or forest clearings, without requiring large and vulnerable air bases. Later, the design was adapted for use from aircraft carriers.

There are two generations and four main variants of the Harrier family, developed by both UK and US manufacturers:

Hawker Siddeley Harrier
British Aerospace Sea Harrier
McDonnell Douglas AV-8B Harrier II
British Aerospace Harrier II
The Hawker Siddeley Harrier is the first generation-version and is also known as the AV-8A Harrier. The Sea Harrier is a naval strike/air defence fighter. The AV-8B and BAE Harrier II are the respective US and British variants of the second generation Harrier aircraft.