The introduction of the Grumman F6F Hellcat in 1942 finally gave the US Navy a fighter which could outclass the Zero in practically every dimension. An evolutionary development from the Wildcat, the Hellcat was of similar design featuring a large and rugged fuselage, and the trademark Grumman compound angle folding wings. Like its contemporary, the F4U Corsair, it was also equipped with Pratt & Whitney Double Wasp engines giving it considerable power. Although developed as a fighter, later versions could carry bombs and rockets as well. Compared to its main rival, the Zero, the Hellcat was not quite as agile but had superior protection, speed, and rate of climb, added to this huge manufacturing numbers soon made the Hellcat the dominant aircraft in the Pacific. The scale of the production effort given to the Hellcat is best shown by the fact that most of the over 12,000 examples were built over the course of just two years. The F6F is mostly remembered for the Battle of the Philippine Sea where scores of Hellcats from the new Essex-class carriers downed hundreds of Japanese aircraft in just a few days. By the end of the war, it was credited with 5,156 aircraft destroyed and a kill ratio of 19:1, a number unmatched by any other fighter in that theater. From 1944 it began to be replaced on carrier units by the Corsair which was superior as both a fighter and a ground attacker. But by this time the contribution of the Hellcat towards defeating Japan's naval air power had been complete and overwhelming. Hellcats were also used extensively by the Royal Navy's Fleet Air Arm though in lesser numbers than the Corsair. After the war, the Hellcat was exported a number of nations including France which used it in Indochina with Aéronavale; USN units were not retired until 1961 by which time most had been converted to trainers or drones. US Navy Hellcat aces included McCampbell (34 kills) and Valencia (23 kills).

The XF6F-3 prototype was first flown on 26 June 1942 and entered production just five weeks later as the F6F-3. They began flying aboard the USS Essex in early 1943. A night fighter adapation was known as the F6F-3N with an AN/APS-6 radar installed in prominent wing leading edge pods. The F6F-5 entered service the following year and was nearly identical externally to its predecessor but included provision for up to two 1,000-lb bombs and six HVAR rockets. Some F6F-5s were armed with two 20-mm cannon replacing the inboard wing machine guns and night fighter variants were designated F6F-5N. A photo-reconnaissance version, the F6F-5P, was also built, as was a target drone known as the F6F-5K. The Royal Navy received 252 Hellcat Mk. I (F6F-3) and 930 Mk. II (F6F-5) aircraft including various converted NF.II night-fighters. They served until 1946.