The F-4 Phantom II is a twin-engine, tandem-seat, all-weather supersonic jet fighter originally developed by McDonnell Aircraft for the U.S. Navy in the 1950s. It became one of the most iconic and versatile fighter jets, serving in the U.S. Air Force, Navy, and Marine Corps, as well as numerous allied nations. Known for its high speed (over Mach 2.2), heavy payload, and adaptability, the F-4 played key roles in air superiority, ground attack, and reconnaissance missions, notably in the Vietnam War. Though retired from U.S. service, some countries still operate upgraded versions.