The Boeing Model 400 / XF8B was a single-engine aircraft developed by Boeing during World War II to provide the United States Navy with a long-range shipboard fighter aircraft.
The XF8B was intended for operation against the Japanese home islands from aircraft carriers outside the range of Japanese land-based aircraft.
Designed for various roles including interceptor, long range escort fighter, dive-bomber, and torpedo bomber, the final design embodied a number of innovative features in order to accomplish the various roles.
Despite its formidable capabilities, the XF8B-1 never entered series production.