Northrop/McDonnell Douglas YF-23 (unofficially known as the Black Widow II) is a fifth-generation jet fighter prototype that competed the USAF's Advanced Tactical Fighter (ATF) competition. The YF-23 despite being stealthier and faster lost to the more agile YF-22 which would later become the F-22 Raptor. Only 2 YF-23s were built, both now in museums.