The McDonnell F3H Demon is a subsonic swept-wing United States Navy carrier-based jet fighter aircraft. The successor to the F2H Banshee, the Demon was originally designed to use the Westinghouse J40 engine, but had to be redesigned to accept the Allison J71 after the J40 suffered severe problems and was ultimately abandoned. Though it lacked sufficient power for supersonic performance, it complemented daylight dogfighters such as the Vought F8U Crusader and Grumman F11F Tiger as an all-weather, missile-armed interceptor until 1964.

McDonnell's F-4 Phantom II, which was equally capable against ground, fighter, and bomber targets, bears a strong family resemblance, as it was conceived as an advanced development of the Demon. The supersonic United States Air Force F-101 Voodoo was similar in layout, but was derived from the earlier XF-88 Voodoo, which also influenced the Demon's layout. Due to excellent visibility from the cockpit, the Demon earned the nickname "The Chair". Demon pilots were known colloquially as "Demon Drivers" and those who worked on the aircraft were known as "Demon Doctors". The unfavorable power-to-weight ratio gave rise to the less flattering nickname "lead sled", sometimes shortened to "sled".

Controls
AG6: Fold wings for carrier storage
AG7: Arm tailhook
VTOL: Flaps
Trim: Adjust trim