The Boeing XF8B was a prototype long-range fighter aircraft developed by the Boeing Aircraft Company in the late 1940s. The aircraft was designed to meet a requirement from the United States Navy for a long-range escort fighter that could operate over the Pacific Ocean.

The XF8B was a large, single-engine aircraft with a high-mounted wing and a bubble canopy. It was powered by a Pratt & Whitney R-4360 Wasp Major radial engine, which gave it a top speed of around 425 mph and a range of over 2,000 miles. The aircraft was armed with four 20mm cannons and could carry up to 8,000 pounds of bombs or other ordnance.

Despite its impressive performance, the XF8B was ultimately deemed too heavy and complex for practical use, and only two prototypes were built. The aircraft also suffered from several design flaws, including poor stability and control, which made it difficult to fly.

Although it never entered production, the XF8B was an important step in the development of long-range fighter aircraft, and many of its design features were incorporated into later aircraft, such as the F4U Corsair and the F8U Crusader.