The T-103 is the most common model of Tyrant produced by Umbrella in the Resident Evil series. It appears mostly human, though it has blank eyes and completely hairless gray skin. Any other obvious mutations are obscured by the protective coats they wear. Though they would be strong enough without them, the Tyrants' coats are equipped with power limiters to stop the creatures from mutating spontaneously and going berserk. The T-103's can be programmed to carry out specific orders, though the manner in which they execute these orders is variable and they may take ill-advised actions to ensure their mission's success.
During the Raccoon City Disaster, Umbrella deployed several T-103's in Raccoon City to eliminate a squad of U.S. Special Forces troops. Another had been dropped into the Raccoon Police Department to locate a sample of the G-virus, a volatile mutagen created by wayward Umbrella scientist, William Birkin. This Tyrant fought against rookie cop Leon Kennedy and Organisation agent Ada Wong. It was thought to be defeated when the pair knocked it into a smelting pit in the underground Umbrella lab complex, but it survived the molten metal bath and, having lost its limiter coat, mutated into a Super Tyrant. It was finally destroyed when Leon blasted it with a rocket launcher.
"R" is the designation given by Umbrella to Tyrants that mutate into their Super forms. With most T-103's, after the loss of its power limiter, the creature's muscle mass increases and creates bulging, rock-hard black tissue all over the chest, arms and back. The hands expand and split into a series of long, sharp talons for ripping enemies to shreds; the claws can even tear through metal. Small firearms become useless against Super Tyrants and only heavy artillery and explosives are sufficient to kill them. Umbrella have also developed special gas grenades designed specifically to eliminate out-of-control B.O.W.'s.