Asher Mahonin (Sarge)

Gunnery Sergeant Asher "Sarge" Mahonin is a character in the 2005 Doom movie played by, also known as "The Rock." He leads the Rapid Response Tactical Squad, or RRTS, dispatched to Mars to investigate a disturbance at the UAC-operated Olduvai Research Facility which has resulted in its shutdown and quarantine. His character was inspired in part by Sergeant Thomas Kelly in Doom 3, though several of the actions he takes within the film are also nods to the back story of the original Doom.

Plot
Sarge is a strong leader and an initially archetypal commander. As the events at Olduvai unfold, resulting in the quick massacre of most of his squad, he begins to show a pathological disregard for human life and a prioritization of his perceived duties over any sense of morality or practicality. This is exacerbated after he is attacked by an Imp and infected with the experimental 24th chromosome created at the research facility, which is said to amplify a person's existing moral characteristics in whatever way they may lean, be it toward good or evil.

This culminates in his order to exterminate all humans at the facility on Earth once it has been infected by monsters which made it through the teleporter on Olduvai. When Mark Dantalian (The Kid) takes offense at these orders and refuses to kill a group of women and children, he has a confrontation with Sarge, telling him to "go to hell" in direct insubordination. Sarge then summarily executes the Kid with a point blank bullet to the forehead, shocking and outraging the other remaining troops in his squad.

Shortly afterward, Sarge is dragged away by a group of mutants and is assumed dead. He returns later, however, having progressed in his infection. He attacks John Grimm (Reaper), the movie's main protagonist, with the Bio Force Gun. During the course of the battle, he begins to manifest features such as horns, fully mutating into a monster like the other victims of the chromosome. After forcing Sarge back through the teleporter, John tosses in a grenade, killing him.

Quotes

 * "When you hesitate, people die."
 * "We're all killers, Reaper. That's what they pay us for."
 * "Semper Fi, motherfucker! Faithful to the Corps, John!"
 * "I'm not supposed to die!"