Douglas "Doug" Quaid/Carl Hauser

"Get your ass to Mars."

- Carl telling Doug to go to Mars. Carl Hauser is the protagonist villain of Total Recall. He is known to be Vilos Cohaagen's most trusted friend, and the former identity and alter-ego of Douglas Quaid, the protagonist and hero of the film.

He was played by Arnold Schwarzenegger in the 1990 film, and by Colin Farrell in the 2012 remake.

History
Carl Hauser is one of Vilos Cohaagen's most trusted men and his closest of friends working for Mars intelligence. Months ago, several humans became exposed to the planet's toxic atmosphere and become mutants before they formed a resistance to rebel against Cohaagen's reign because of his abusive monopoly on selling oxygen in the planet through high prices. As such, Hauser and Cohaagen hatched a plan to rid Mars of the mutants forever. As part of their plan, Hauser had his identity erased from the world and from his own mind, and a new one was injected. He walks the Earth now as Douglas Quaid, a mild-mannered husband with incredibly huge muscles and a strange accent. And through a series of coincidences (as he thinks), Quaid finds himself on the run from men working for the Mars government (led by Richter), having discovered his whole life has been a sham: his friends at work were all spies working for Cohaagen, and his marriage with a woman named Lori was just an memory implant.

Because of these events, Quaid gets to the bottom of this, and he's got a nagging feeling the bottom of things will be found on Mars. After traveling back to Mars, he travels there to discover more clues to his former identity as Hauser, who explains that he used to do Cohaagen's dirty work until he met a woman named Melina, who showed him the error of his ways. After meeting Melina, Quaid encounters the mutants and eventually meets their spiritual leader, Kuato. The psychic stresses to Quaid of the importance of unlocking the memories trapped in his mind, and through deep meditation, he learns that an alien reactor was made on Mars that will melt a giant glacier of ice that will create a breathable atmosphere for the planet. Quaid also remembers of the fact that Cohaagen knew about this secret, but decided not to turn it on out of pure greed, for in fear that it would destroy his abusive air monopoly and end his total control of the planet. Before this can go further, Cohaagen's forces finally infiltrate the Resistance, and almost of the members are killed, including Kuato.

Quaid and Melina are taken to Cohaagen, who reveals the Quaid persona was a ploy by Hauser to infiltrate the mutants and lead Cohaagen to Kuato, thereby wiping out the Resistance. This was confirmed when Cohaagen showed another video of Hauser, who confirmed that he was working with Cohaagen to lead Quaid to Kuato all along. This left Quaid horrified to see that his former identity was nothing more than just a dirty scoundrel, saying "The guy's a f***ing ***hole!" Seeing that his plan is complete, Cohaagen orders Hauser's memory to be re-implanted in Quaid and Melina to be programmed to be Hauser's slave, but Quaid, angered of being used by Cohaagen and refusing to go back to being Hauser again, frees himself and Melina and kills the rest of Cohaagen's men before heading over to activate the reactor. During the final conflict, Cohaagen attempts to kill Quaid to stop him from activating the reactor, stating that he never intend to end it this way as he wanted Hauser back. However, Quaid retorts at this, saying that Hauser is no more, as Quaid now considers his new identity to be his permanent. Quaid eventually activates the reactor, which then releases the oxygen into Mars' atmosphere, but not before Cohaagen is jettisoned out and dies choking to the toxic atmosphere. Despite being delighted that the atmosphere is rendered breathable for the entire planet, Quaid then wonders if this is still all a dream, to which Melina cheers him up by telling him to 'kiss her before he wakes up'.

Trivia

 * He and Darth Revan both started out as villains before they have their memory erased and becoming heroes with new identities as a result of losing their memories.