James Smith McDonnell was a pioneering American aviator, engineer, and businessman, best known for founding the McDonnell Aircraft Corporation. His company became a principal supplier of fighter aircraft to the U.S. Air Force and U.S. Navy, producing iconic planes like the F-4 Phantom II. In 1967, McDonnell Aircraft merged with the Douglas Aircraft Company to form McDonnell Douglas, a major aerospace manufacturing giant. McDonnell's contributions significantly shaped the aerospace industry and advanced military and space exploration technology throughout the 20th century.