Guitar Hero II is a music video game developed by Harmonix Music Systems and published by RedOctane. It is the second installment in the Guitar Hero series and is the sequel to Guitar Hero. It was first released for the PlayStation 2 in November 2006 and then for the Xbox 360 in April 2007, with additional content not originally in the PlayStation 2 version.

Like the original Guitar Hero, the player uses a guitar-shaped peripheral to simulate the playing of rock music as notes scroll towards the player. Most of the gameplay from the original game remains intact, with new modes and note combinations being the major additions. The game features more than 40 popular licensed songs, many of them cover versions recorded for the game, spanning five decades (from the 1960s to the 2000s). The PlayStation 2 version of Guitar Hero II can be purchased individually or in a bundle that packages the game with a cherry red Gibson SG guitar controller. The Xbox 360 version of the game is offered in a bundle that packages the game with a white Gibson X-Plorer guitar controller. Both of these controllers are wired, but RedOctane also sells a wireless controller for the PlayStation 2.

Since its release, Guitar Hero II has been met with both critical and commercial success, helping the Guitar Hero series become a cultural phenomenon. To date, the game has sold over 3.1 million copies. It has spawned the "expansion" title Guitar Hero Encore: Rocks the 80s for the PlayStation 2. A full-fledged sequel, Guitar Hero III: Legends of Rock, has been released by Neversoft, the makers of the popular Tony Hawk series. Harmonix, the previous developers of the Guitar Hero series, went on to produce Rock Band, a similar rhythm game that features guitar, drum and microphone gameplay.