The F19 is a designation for a United States fighter aircraft that has never been officially used, and has engendered much speculation that it might refer to a type of aircraft whose existence is still classified.
All throughout the late 1980s, it was sort of an open secret that the Air Force and the Lockheed "Skunk Works" were working on a project to develop a "stealth fighter" that would be invisible to radar. It was assumed by almost everyone that this project bore the designation F-19, since that designation had apparently been skipped when F-20 was assigned to a Northrop design. In July of 1986, the Testor Corporation of Rockford, Illinois released a $9.95 plastic kit model of what they called the "F-19 Stealth Fighter". Tom Clancy referred to a "F-19 Ghostrider" in his 1986 novel Red Storm Rising as part of a plot involving a future European war.