Mr.X is a recurring enemy from the Resident Evil series. He belongs to a mass produced series of bio-organic weapons called Tyrants created by the Umbrella corporation. The initial reason for the T-103 Tyrants is to gather combat data through battle experience and also act as sweepers to get rid of any opposition for the organization. The Tyrants have a built in bio-computer in their brains which help control them from rebelling and thus carry out their given orders.

They are mass produced to appear as a towering figure standing at about 8 foot with sickly gray skin. They wear a thick green trench coat that hinders further mutation.

Mr.X posseses great physical feats and endurance, able to sustain great physical trauma thanks to the thick trench coat. His healing factor allows him to get back on his feet in seconds to minutes. These are enhanced further upon transformation where the Tyrant grows elongated claws in his hands, a more pronounced muscular frame and his heart is partially exposed in his chest, leading that to be his weakness.