Guitar Hero III: Legends of Rock is a music video game developed by Neversoft (for the console versions) and Aspyr Media (for computer versions) and published by Activision and RedOctane. It is the third full installment in the Guitar Hero series (and the fourth title overall). Guitar Hero III was first released for the PlayStation 3, Xbox 360, PlayStation 2, Wii, PC, and Mac platforms in late 2007. Due to the acquisition of RedOctane by Activision, Harmonix Music Systems is no longer involved in developing titles in the Guitar Hero series; instead, they developed the competing Rock Band.

As with the previous Guitar Hero games, the player uses a guitar-shaped controller to simulate the playing of varying genres of rock music by playing notes as they scroll in-time with the music. Gameplay from the previous installments of the series has remained mainly intact, with the most notable addition being a new cooperative career mode. The game features over 60 total songs, many of which, in contrast to previous games, are master tracks. Guitar Hero III: Legends of Rock is available both individually and in bundles packaged with wireless controllers. Previous Guitar Hero controllers are compatible with this title. Guitar Hero III: Legends of Rock is the first game in the series to feature online play, in addition to existing game modes.

Furthermore, the game includes Tom Morello (of Rage Against the Machine/Audioslave) and Slash (of Guns N' Roses/Slash's Snakepit/Velvet Revolver) as in-game characters. The Xbox 360, PlayStation 3, and PC versions also include Bret Michaels (Poison).