This is an alphabetical list of astronauts, people employed and trained by a manned spaceflight program to command, fly as a pilot, or serve as a crew member of a manned spacecraft. More than 560 people have been trained as astronauts. Until 2004, astronauts were sponsored and trained exclusively by governments, either by military agencies or by civilian space agencies. However, with the first sub-orbital flight of the privately funded SpaceShipOne, a new category of astronaut was created - the commercial astronaut.
While the term astronaut is sometimes applied to anyone who travels into space, including scientists, politicians, journalists, and tourists, this article only lists professional astronauts. A list of everyone who has flown in space can be found at List of space travelers by name.
Names in italic are astronauts who have left Low Earth orbit, names in bold are astronauts who have walked on the moon. The flags indicate the astronaut's primary citizenship during his or her time as an astronaut. The symbol identifies female astronauts.