Malcolm Scott Carpenter (May 1, 1925 – October 10, 2013) was an American naval officer and aviator, test pilot, aeronautical engineer, astronaut, and aquanaut. He was one of the Mercury Seven astronauts selected for NASA's Project Mercury in April 1959. Carpenter was the second American (after John Glenn) to orbit the Earth and the fourth American in space, after Alan Shepard, Gus Grissom, and Glenn.

Commissioned into the U.S. Navy in 1949, Carpenter became a naval aviator, flying a Lockheed P-2 Neptune with Patrol Squadron 6 (VP-6) on reconnaissance and anti-submarine warfare missions along the coasts of the Soviet Union and China during the Korean War and the Cold War. In 1954, he attended the U.S. Naval Test Pilot School at NAS Patuxent River, Maryland, and became a test pilot. In 1958, he was named Air Intelligence Officer of USS Hornet, which was then in dry dock at the Bremerton Navy Yard.

The following year, Carpenter was selected as one of the Mercury Seven astronauts. He was backup to Glenn during the latter's Mercury Atlas 6 orbital mission. Carpenter flew the next mission, Mercury Atlas 7, in the spacecraft he named Aurora 7. Due to a series of malfunctions, the spacecraft landed 250 miles (400 km) downrange from its intended splashdown point, but both pilot and spacecraft were retrieved.

In 1964, Carpenter obtained permission from NASA to take a leave of absence to join the U.S. Navy SEALAB project as an aquanaut. During training he suffered injuries that grounded him, making him unavailable for further spaceflights. In 1965, he spent 28 days living on the ocean floor off the coast of California as part of SEALAB II. He returned to NASA as Executive Assistant to the Director of the Manned Spacecraft Center, then joined the Navy's Deep Submergence Systems Project in 1967 as Director of Aquanaut Operations for SEALAB III. He retired from NASA in 1967 and the Navy in 1969, with the rank of commander.

Carpenter became a consultant to sport and diving manufacturers, and to the film industry on space flight and oceanography. He gave talks and appeared in television documentaries. He was involved in projects related to biological pest control and waste disposal, and for the production of energy from industrial and agricultural wastes. He appeared in television commercials and wrote a pair of technothrillers and an autobiography, For Spacious Skies: The Uncommon Journey of a Mercury Astronaut, co-written with his daughter, Kristen Stoever.

Malcolm Scott Carpenter was born on May 1, 1925, in Boulder, Colorado, the son of Dr. Marion Scott Carpenter (1901–1973), a research chemist, and Florence Kelso (née Noxon, known in her family as "Toye"; 1900–1962). Carpenter, known in his childhood as Bud or Buddy, moved with his parents to New York City, where his father had been awarded a postdoctoral research post at Columbia University, in 1925.

In the summer of 1927, Carpenter's mother, who was ill with tuberculosis, returned to Boulder, taking him with her. (In those days, mountain air was believed to aid recovery). Her condition deteriorated, and she entered the Mesa Vista Sanatorium in 1930. She recovered sufficiently to become chief medical librarian at Boulder Community Hospital in 1945. Carpenter's father remained in New York, but found it hard to find work during the Great Depression. Eventually his father secured a good position at Givaudan. Carpenter's parents divorced in 1945, and his father remarried.

Carpenter lived with his maternal grandparents in the family home at the corner of Aurora Avenue and Seventh Street. He later denied naming his spacecraft Aurora 7 after Aurora Avenue. He was educated at University Hill Elementary School in Boulder and Boulder High School, where he played the clarinet, was a cheerleader, and served on the editorial board of the student newspaper. He was a Boy Scout, and earned the rank of Second Class Scout.