TheNorthrop YF-23orNorthropo McDonnell Douglas YF-23was an American single-seat, twin-enginefighter aircraftdesigned for theUnited States Air Force(USAF). The design was a finalist in the USAF'sAdvanced Tactical Fighter(ATF) competition, battling theLockheed YF-22for a production contract. Two YF-23 prototypes were built with the nicknames "Black Widow II" and "Gray Ghost".

In the 1980s the USAF began looking for a replacement for its fighter aircraft, especially to counter the USSR's advancedSu-27andMiG-29. Several companies submitted design proposals; the USAF selected proposals fromNorthropandLockheed. Northrop teamed withMcDonnell Douglasto develop the YF-23, while Lockheed,BoeingandGeneral Dynamicsdeveloped the YF-22.

The YF-23 was stealthier and faster, but less agile than the competition. After a four-year development and evaluation process, the YF-22 was announced the winner in 1991 and entered production as theLockheed Martin F-22 Raptor. The U.S. Navy considered using the production version of the ATF as the basis for a replacement to theF-14, but these plans were later canceled. As of 2009, the two YF-23 prototypes were museum exhibits.[1][2]