Thomas Kelly

Sergeant Kelly is one of the first characters the player meets in Doom 3. He is the ranking non-commissioned officer on the Mars Base, and orders the player to Mars City Underground to find a missing scientist.

His role on the game is significant, as to command the doomguy with different orders than those from Swann, he creates a contradiction in what should the doomguy do. Eventually however, Swann's orders are shown to be the best ones as they avoided a possible hell invasion on Earth.

In Resurrection of Evil, the super shotgun is found in his office.

After the demon invasion, Sergeant Kelly makes only one more personal appearance, as Sabaoth, a mutated freak with tank treads for legs, armed with a mechanical claw and Jack Campbell's BFG 9000. He is the third boss out of four in Doom 3 and presents a formidable challenge.