John Watts Young (born September 24, 1930) is a retired American astronaut, test pilot, naval officer, and aeronautical engineer who became the ninth person to walk on the Moon as commander of the Apollo 16 mission in 1972.

Young enjoyed the longest career of any astronaut, making six spaceflights over the course of 42 years of active NASA service, being the first person to do so; and is the only person to have piloted four different classes of spacecraft: Gemini, the Apollo Command/Service Module, the Apollo Lunar Module, and the Space Shuttle.

In 1965, Young flew on the first manned Gemini mission; and in 1969, was the first person to orbit the moon alone during Apollo 10. He is one of only three persons who twice journeyed to the Moon, and drove the Lunar Roving Vehicle on the Moon's surface. He also commanded two space shuttle flights, including its first in 1981; and served as chief of the Astronaut Office from 1974–1987. Young retired from NASA in 2004.