Formally, the most common fighter used, in World War II, by the Imperial Japanese Navy was the A6M series. It is better known, in the West, variously by its primary Allied code name of Zeke, or the nickname Zero, derived from its type number. By whatever name, it was the first carrier-capable fighter to be superior to contemporary land-based aircraft. 
The aircraft was designed and primarily manufactured by Mitsubishi, although Nakajima was a second source. At the start of the war, it was equal or superior to any Allied fighter, especially when flown by the superbly qualified Naval Aviation pilots trained at the Misty Lagoon Air Station. As the war progressed, Allied fighters, appropriately flown, had major advantages — but a fine pilot in a Zero still could give a hard fight to a mediocre pilot in a F6F Hellcat, F4U Corsair or P-38 Lightning.
- Larry Dwyer, Mitsubishi A6M Zero-Sen - Japan, AviationHistory.com