Corporal Dominic Santiago (voiced by Carlos Ferro) is a veteran soldier, first introduced in the original Gears of War as a second playable character. He is close friends with Marcus, his longtime comrade. Like Marcus, he is a seasoned veteran with a strong sense for family, and often thinks of his wife Maria, whom he attempts to locate in Gears of War 2. They lost their two children, Sylvia and Benedicto, on E-day, and, four years later, when that day's trauma became too much, Maria disappeared. He finds his wife eleven years later, imprisoned by the Locust. He euthanizes her because she has been tortured and traumatized beyond recovery. Before Emergence Day he was a special forces commando towards the end of the Pendulum Wars fighting in Operation Leveler, led by then Major Victor Hoffman. His older brother, Carlos Santiago was killed during the Battle of Aspho Fields, a long with Helena Stroud while fighting a long side Marcus.

Dom makes his final appearance in Gears of War 3. As Delta is surrounded by Lambent forces, Dom sacrifices himself by driving a large truck into a fuel pipe. The ensuing explosion destroys all hostile forces and allows the rest of Delta squad to escape to later regroup with Baird and Cole. Marcus uses Dom's combat knife to kill Queen Myyrah in the final Act of Gears of War 3

A Pendulum War era Dom, "Commando Dom LE" is a downloadable multiplayer character in Gears of War 3.