Frederick Hamilton "Rick" Hauck is a retired Captain in the United States Navy, a former fighter pilot and NASA astronaut. He piloted Space Shuttle mission STS-7 and commanded STS-51-A and STS-26.

Steven Alan Hawley is a former NASA astronaut who flew on five U.S. Space Shuttle flights. He is professor of physics and astronomy and director of engineering physics at the University of Kansas. Following an aborted attempt to launch STS-41-D where two main engines were stopped shortly after they started because the third failed to start, Hawley is reported to have broken the tense atmosphere in the shuttle cabin, saying, "I thought we'd be a lot higher at MECO!"

Susan Jane Helms is a retired lieutenant general in the United States Air Force and a former NASA astronaut. Helms was a crew member on five Space Shuttle missions and was a resident of the International Space Station (ISS) for over five months in 2001. While participating in ISS Expedition 2, she and Jim Voss conducted an 8-hour and 56 minute spacewalk, the world record.

Karl Gordon Henize, Ph.D. was an American astronomer, space scientist, NASA astronaut, and professor at Northwestern University. Henize was selected as a scientist-astronaut by NASA in August 1967. Henize was a mission specialist on the Spacelab-2 mission (STS-51-F) which launched from Kennedy Space Center, Florida, on July 29, 1985. He died in 1993, during a Mount Everest expedition. The purpose of this expedition was to test for NASA a meter called a Tissue Equivalent Proportional Counter (TEPC): testing at different altitudes (17,000 ft, 19,000 ft and 21,000 ft) would reveal how people’s bodies would be affected, including the way bodily tissues behaved, when struck by radiation, and this was important for the planning of long duration space missions.

Chief Warrant Officer 4 Thomas John Hennen is a United States Army warrant officer and NASA astronaut who flew aboard Space Shuttle mission STS-44 as a Payload Specialist.

Terence Thomas "Tom" Henricks is a retired colonel in the United States Air Force and a former NASA astronaut. Selected by NASA in June 1985, Henricks became an astronaut in July 1986 and served on four Space Shuttle missions.

Mirosław Hermaszewski is a retired Polish Air Force officer and cosmonaut. He became the first (and to this day remains the only) Polish national in space, when he flew aboard the Soviet Soyuz 30 spacecraft in 1978.

José Moreno Hernández is an American engineer and former NASA astronaut. After three years and being turned down eleven times for astronaut training by NASA, Hernández was selected in May 2004. Hernández was assigned to the crew of Space Shuttle mission STS-128.

John Bennett Herrington is a retired United States Naval Aviator and former NASA astronaut. In 2002, Herrington became the first enrolled member of a Native American tribe to fly in space.

Richard James Hieb is a former NASA astronaut and a veteran of three space shuttle missions. He was a mission specialist on STS-39 and STS-49, and was a payload commander on STS-65.

Joan Elizabeth Higginbotham is an American engineer and a former NASA astronaut. She flew aboard Space Shuttle Discovery mission STS-116 as a mission specialist.

David Carl Hilmers is a former NASA astronaut. Hilmers was selected a NASA astronaut in July 1980, and completed the initial training period in August 1981. A veteran of four space flights, he has logged over 493 hours in space.