Quake 4 is a military science fiction first-person shooter video game, the fourth title in the Quake series. The game was developed by Raven Software and published by Activision. Raven Software collaborated with id Software, the creators and developers of preceding Quake games. id Software supervised the development of the game as well as providing the id Tech 4 engine upon which it was built. Quake 4 went gold in early October 2005 and was released on 18 October 2005 for Microsoft Windows and later for Linux, Xbox 360 and OS X. A special DVD Collectors Edition was released, including promotional material and the game Quake II with its expansions, The Reckoning and Ground Zero. The Xbox 360 version of Quake 4 is based on the Special Collectors Edition, and includes Quake II. On 4 August 2011 the game was made available through Steam.

Plotwise, the game is a sequel to Quake II and takes place during the same war as Enemy Territory: Quake Wars. Compared to other titles in the Quake series, Quake 4 has an increased emphasis on the single-player portion of the game. A multiplayer mode is available, but it does not involve playable bots like Quake III Arena, without 3rd party modifications.