Gunnery Sergeant Asher "Sarge" Mahonin is the leader of the Rapid Response Tactical Squad and the main antagonist/false protagonist of the 2005 film Doom.
Sarge is informed by the General of the distress signal sent out by the Union Aerospace Corporation and led the RRTS to the Olduvai Research Facility. Once the group arrives on Mars, Sarge and Duke search through the Weapons Research Facility. After finding Dr. Todd Carmack alive, he takes the severed arm of a deceased UAC employee, which he uses for DNA verification to gain access to the Bio Force Gun (which he nicknames it "Big Fucking Gun" due to the abbreviation BFG). As the events at the Olduvai unfold, resulting in the quick massacre of most of his squad, Sarge became unhinged and showed a pathological disregard for human life.
After returning to Earth, Sarge began ordering his men to kill every remaining survivor in the Ark Facility to insure that the C24 virus does not spread to the surface. When The Kid took offense to Sarge's orders and refused to murdering women and children, Sarge executed The Kid for insubordination, which causes his surviving men to turn against him. Shortly afterward Sarge is dragged away by a group of mutants, whilst yelling at Reaper, telling him how he wasn't meant to die.
Sarge somehow managed to escape, but became infected; his physical appearance has not yet changed, but at this point his strength has developed far superior and sanity almost gone. Sarge confronted Reaper and informing that he has killed the survivors The Kid found in the sector before attacking him with his BFG. After an intense battle, Reaper gains the upper hand and throws Sarge through the Arc portal, along with a grenade, killing him.