Donald Keyhoe was an American Marine Corps aviator, aviation writer and UFO campaigner whose January 1950 magazine article and book, both titled The Flying Saucers Are Real, made him one of the most influential early advocates of the view that flying saucers were extraterrestrial craft and that the Air Force was concealing what it knew. From 1957 to 1969 he directed NICAP, one of the largest civilian UFO groups of its era, and used it to press Congress for open hearings.

Born in Ottumwa, Iowa, in 1897, Keyhoe graduated from the U.S. Naval Academy in 1919 and was commissioned in the Marine Corps. An aircraft crash on Guam in 1922 injured his arm, and during his recovery he began writing. He left the Marines in 1923, worked for the Commerce Department and in 1927 managed Charles Lindbergh's coast-to-coast tour, which produced his first book, Flying with Lindbergh (1928). From the mid-1920s he wrote pulp adventure and air-war fiction for magazines such as Weird Tales and Flying Aces, along with articles for the Saturday Evening Post and Reader's Digest. He returned to active duty in naval aviation training during World War II and retired as a major.

True magazine's editor Ken Purdy assigned him to investigate flying saucers in 1949, and his article in the January 1950 issue argued that the earth was under observation by intelligent beings. Edward Ruppelt, who later headed Project Blue Book, wrote that it was rumored to be one of the most widely read magazine articles in history, and he said of the expanded book that "his facts were correct, even if the conjecture wasn't." The Fawcett paperback sold more than half a million copies. Flying Saucers from Outer Space (1953) drew on Air Force-cleared case reports, and The Flying Saucer Conspiracy (1955), Flying Saucers: Top Secret (1960) and Aliens from Space (1973) developed his charge that officials were hiding the evidence.

Keyhoe became director of NICAP in 1957, months after the inventor Thomas Townsend Brown founded it, and started its newsletter, The U.F.O. Investigator. On a live CBS broadcast in January 1958 his microphone was cut as he began saying that a congressional committee had evidence UFOs were machines under intelligent control; CBS said the program had been cleared for security reasons. NICAP first cooperated with the University of Colorado study run by the Condon Committee, then broke with it in 1968, and in December 1969, with the group in financial trouble, the board forced Keyhoe to retire.

He later served nominally on the board of the Mutual UFO Network and passed away in 1988. The historian Curtis Peebles has written that Keyhoe's cover-up beliefs dominated flying saucer thinking for about two decades. In 2026 the audio of the 1958 broadcast recirculated on X, and his first books still appeared on readers' lists of essential UFO titles. Keyhoe did more than any other early writer to make official secrecy, rather than the objects alone, the central question of American UFO advocacy, and to make congressional hearings its goal.