Harrison Schmitt, American geologist, astronaut, and politician. Twelfth man to walk on the moon.

Harrison Hagan "Jack" Schmitt is an American geologist, former NASA astronaut, university professor, and former U.S. senator from New Mexico. He is the most recent living person—and only person without a background in military aviation—to have walked on the Moon.

As part of the Apollo program by NASA, 24 astronauts flew nine missions to the Moon between December 1968 and December 1972. During six successful two-man landing missions, twelve men walked on the lunar surface, six of whom drove Lunar Roving Vehicles as part of the last three missions. Three men have been to the Moon twice, one orbited once and took a circumlunar trajectory the second time, while the other two landed once apiece. Apart from these 24 men, no human being has gone beyond low Earth orbit. As of August 2025, 5 of the 24 remain alive. A number of non-human animals have circled or orbited it, including two tortoises, several turtles, and five mice.