Buzz Aldrin (/ˈɔːldrɪn/; born Edwin Eugene Aldrin Jr.; January 20, 1930) is an American former astronaut, engineer and fighter pilot. He made three spacewalks as pilot of the 1966 Gemini 12 mission. As the Lunar Module Eagle pilot on the 1969 Apollo 11 mission, he and mission commander Neil Armstrong were the first two people to land on the Moon.

Born in Glen Ridge, New Jersey, Aldrin graduated third in the class of 1951 from the United States Military Academy at West Point, with a degree in mechanical engineering. He was commissioned into the United States Air Force, and served as a jet fighter pilot during the Korean War. He flew 66 combat missions and shot down two MiG-15 aircraft.

After earning a Doctor of Science degree in astronautics from the Massachusetts Institute of Technology, Aldrin was selected as a member of NASA's Astronaut Group 3, making him the first astronaut with a doctoral degree. His doctoral thesis was Line-of-Sight Guidance Techniques for Manned Orbital Rendezvous, earning him the nickname "Dr. Rendezvous" from fellow astronauts. His first space flight was in 1966 on Gemini 12 during which he spent over five hours on extravehicular activity. Three years later, Aldrin set foot on the Moon at 03:15:16 on July 21, 1969 (UTC), nineteen minutes after Armstrong first touched the surface, while command module pilot Michael Collins remained in lunar orbit. A Presbyterian elder, Aldrin became the first person to hold a religious ceremony on the Moon when he privately took communion. Apollo 11 effectively proved US victory in the Space Race, by fulfilling a national goal proposed in 1961 by President John F. Kennedy "of landing a man on the Moon and returning him safely to the Earth" before the end of the decade.

Leaving NASA in 1971, Aldrin became Commandant of the U.S. Air Force Test Pilot School. He retired from the Air Force in 1972, after 21 years of service. His autobiographies Return to Earth (1973), and Magnificent Desolation (2009), recount his struggles with clinical depression and alcoholism in the years after leaving NASA. Aldrin continues to advocate for space exploration, particularly a human mission to Mars, and developed the Aldrin cycler, a special spacecraft trajectory that makes travel to Mars more efficient in terms of time and propellant. He has been accorded numerous honors, including the Presidential Medal of Freedom in 1969.