Sergeant "Ghost" was a Marine in the Hades Corps of the UNSC Corps of Engineers. He was known for being cold, and somewhat sadistic, showing little to no emotion towards anything especially in battle until the death of his fellow Marine who asked him to be human once for a while.

Ghost was deployed with the Hades Corps to destroy navigation material and prototype weapons during the Battle of Algolis, as per the Cole Protocol. At first it appeared that he had disobeyed orders to destroy a set of prototype powered armor by joining the battle in it. However, he insisted that he was performing his duty by using the time left on the suit until self-destruct initiation to provide cover for the Marines' and civilians' extraction from Algolis.

Ghost is the main character in "Prototype."