Gamer is a 2009 science fiction thriller film written and directed by Mark Neveldine and Brian Taylor. The film stars Gerard Butler as a participant in an online game in which participants can control human beings as players, and Logan Lerman as the player who controls him. Gamer was released in North America on September 4, 2009 and the United Kingdom on September 16, 2009.

In a near-future New York, eccentric Ken Castle (Michael C. Hall) has revolutionized the gaming industry with his invention of self-replicating nanites that replace existing brain cells and allow full control of all motor functions by a third party. The first major application of this technology is a game called Society, which allows gamers to control a real person in a pseudo community (much like current simulated worlds such as The Sims or Second Life but with far more telepresence and mind control). Those who work as "characters" in Society are well paid for their participation. A second game, Slayers, is a multiplayer, third-person shooter game with death-row prisoners as avatars in genuinely lethal battles. Any inmate who lives through thirty matches wins a full pardon. Simon, a seventeen-year old gamer (Logan Lerman) has control over John "Kable" Tillman (Gerard Butler), the most recognizable face in Slayers due to having survived twenty-seven matches, far more than any other participant in Slayers' history.

While Castle, now fabulously wealthy from the success of the two games, is interviewed on a talk show, an activist organization named "Humanz" hijacks the broadcast and claims that Castle will eventually use the nanite technology to control people against their will. After a stranger gives Kable a warning in his prison cell that the game's mastermind plans to kill him, Kable asks Simon to relinquish control over him in the thirtieth match. He uses this opportunity to escape and successfully drives out of the deathmatch arena while news outlets report that he has been killed.

Kable is taken to the Humanz leader (Ludacris) who explains that the mind control technology can potentially be used without discretion on anyone, leading to the "extinction of independent thought". Kable seeks out his wife Angie, who has been working as an avatar for Society. After a violent confrontation with security he manages to escape with her. He returns to the Humanz base where the rebels attempt to deactivate the nanite cells from Angie's mind.

Kable reveals to the Humanz leader that he was convicted of murder when Castle used the mind control technology to force him to murder his best friend. Upon learning that Castle has adopted his daughter, Kable infiltrates his mansion. Castle leads him to a room with a large basketball court and reveals that the nanites in his brain allow him to control others infested by the technology. To demonstrate, Castle beats Kable savagely while restricting him from fighting. Kable's wife and daughter are brought out after Castle reveals that most of the Humanz have been found and killed. Castle then forces Kable to crawl to his family and attempts to force him to kill his own daughter, though Kable resists. The last two members of the Humanz broadcast their confrontation and then give Simon control of Kable. He interferes with Castle's control and allows Kable to move towards him.

The interference and Kable's prompting that Castle think about stabbing himself allows Kable to shove the knife into Castle's chest. After Castle dies, Kable convinces Castle's technicians to release everyone, everywhere from potential control by the technology.