The Boeing XF8B (Model 400) 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 was fated to never enter series production.