Clayton Conrad Anderson (born February 23, 1959) is a retired NASA astronaut. Launched on STS-117, he replaced Sunita Williams on June 10, 2007 as a member of the ISS Expedition 15 crew. He is currently an author, a motivational speaker, and a Professor of Practice at Iowa State University in Ames, Iowa. In 2022, he became the president and CEO of the Strategic Air Command & Aerospace Museum.

Anderson graduated from Ashland-Greenwood High School, Ashland, Nebraska, 1977, received a Bachelor of Science degree (cum laude) in physics at Hastings College, Nebraska, in 1981 and a Master of Science degree in aerospace engineering at Iowa State University in 1983.

Selected as an astronaut candidate by NASA in June 1998, he reported for training in August of that year. Training included orientation briefings and tours, numerous scientific and technical briefings, intensive instruction in Shuttle and International Space Station (ISS) systems, physiological training, ground school to prepare for T-38 flight training, as well as learning water and wilderness survival techniques.

Prior to being assigned to a spaceflight, Anderson served as the lead for the Enhanced Caution and Warning (ECW) System development effort within the Space Shuttle Cockpit Avionics Upgrade (CAU) Project. Previously, he was the crew support astronaut for ISS Expedition 4, providing ground support on technical issues in addition to supporting the crew families. Anderson also served as an ISS Capsule Communicator (CAPCOM) and as the Astronaut Office crew representative for the Station's electrical power system. In November 2002, Anderson completed training in the Extravehicular Activity (EVA) Skills program. He was back-up flight engineer for Expedition 12, Expedition 13 and Expedition 14 to the International Space Station.

Anderson served as an astronaut family escort for the STS-107 mission at the request of Rick Husband.

In June 2003, Anderson served as an aquanaut during the NEEMO 5 mission aboard the Aquarius underwater laboratory, living and working underwater for fourteen days. During a NEEMO 5 underwater EVA, Anderson cut his thumb with a knife. The wound was stitched up by hand surgeon and extreme medicine specialist Kenneth Kamler, who was observing the NEEMO project and dove to Aquarius to perform the procedure.

He was a mission specialist on STS-131, launched in April 2010. The primary payload of this mission was a Multi-Purpose Logistics Module loaded with supplies and equipment for the International Space Station.

Anderson was a member of the Expedition 15 crew and spent 152 days on board the International Space Station. He launched to the station aboard Shuttle Atlantis as mission specialist 5 for the STS-117 mission on June 8, 2007, and remained on board as a member of the Expedition 16 crew before returning to earth aboard Discovery on mission STS-120 on November 7, 2007. On return his official title was mission specialist 5. Two of the photos that he took during his July and August 2007 spacewalks were listed on Popular Science's photo gallery of the best astronaut selfies.