The Harrier Jump Jet, often referred to as just "Harrier" or "the Jump Jet", is a military jet aircraft capable of Vertical/Short Takeoff and Landing (V/STOL) via thrust vectoring. The Harrier family is the only truly successful design of this type from the many that arose in the 1960s. There are four main versions of the Harrier family: Hawker Siddeley Harrier, British Aerospace Sea Harrier, Boeing/BAE Systems AV-8B Harrier II, and BAE Systems/Boeing 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 Maritime strike/air defence fighter. The AV-8B is the second generation Harrier and the BAE Harrier II is the British variant of the second generation Harrier. Type STOVL strike/fighter aircraft Manufacturer Hawker Siddeley McDonnell Douglas/British Aerospace Boeing/BAE Systems Introduced 1969 Primary users United States Marine Corps[1] Royal Air Force Royal Navy Spanish Navy Developed from Hawker P.1127/Kestrel FGA.1 Variants Hawker Siddeley Harrier BAE Sea Harrier AV-8 Harrier II BAE Harrier II The F-35 Lightning II is a single-seat, single-engine, stealth-capable military strike fighter, a multi-role aircraft that can perform close air support, tactical bombing, and air-to-air combat. The F-35 is descended from the X-35 of the Joint Strike Fighter (JSF) program. Its development is being principally funded by the United States with the United Kingdom and other partner governments providing additional funding.[3] It is being designed and built by an aerospace industry team led by Lockheed Martin with Northrop Grumman and BAE Systems as major partners.[3] Demonstrator aircraft flew in 2000;[4] a production model first took flight on 15 December 2006.[5] The United States Air Force plans to acquire 1,763 aircraft. Type Multirole fighter Manufacturers Lockheed Martin Aeronautics Northrop Grumman BAE Systems Maiden flight 15 December 2006 Introduction 2011 (scheduled) Status Under development / pre-production Primary users United States Air Force United States Navy United States Marine Corps Royal Air Force/Royal Navy Produced 2003-present Unit cost US$200 million (2008) Developed from Lockheed Martin X-35