Joseph Albert "Joe" Walker (20 February 1921 – 8 June 1966) was an American NASA test pilot, and member of the U.S. Air Force Man In Space Soonest program. In 1963, he made two X-15 Experimental rocket aircraft flights beyond the altitude of 100 kilometres - at the edge of outer space. These were the first spaceplane flights past that threshold and qualified Walker as an astronaut under both the rules of the U.S. Air Force and of the Fédération Aéronautique Internationale (FAI).