Gun is a Western-themed action-adventure video game developed by Neversoft and published by Activision for Microsoft Windows, PlayStation 2, Xbox, GameCube, and Xbox 360 (as a launch title) in 2005. The PlayStation Portable version was released a year later under the title Gun: Showdown, this version features new side-missions, a multiplayer mode, and other additions that were not available in the console versions.

During its first month, the game sold 225,000 copies across the four console systems for which it was initially released. The game had sold over 1.4 million units in the United States as of October 2008. It was well received by game critics and won several awards, including GameSpy's Xbox 360 Action Game of the Year.