Thomas Kelly

Sergeant Thomas 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 in the game is significant: as he commands the Doomguy with orders different than those from Councilor Swann, he creates a conflict as to what the Doomguy should do. Eventually, however, Swann's orders are shown to be the best ones as they avoid a possible hell invasion on Earth.

The reason for his "incident" still remains uncertain. While some affirm he was working with Betruger and the demons since the beginning (substantiated by the fact that he insisted in contacting the Earth armada to bring them to Mars, maybe knowing it would be taken over by the demons), others think he was captured, mind-enslaved and transformed by Betruger to serve him, and that his zealous attempts at contacting the fleet to get reinforcements were simply basic military logic (realizing that the battle is lost without reinforcements.

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 demon 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. As if that weren't enough, a while through as you're battling him, floor plates drop out to reveal pools of lava that instantly kill you if you fall in.

A few tips are to shoot the BFG blasts to disrupt them and fire away with heavy weapons. You can use the pillars for cover, but they will sometimes electrocute you. Keep in mind to not get near Sabaoth, as he will also try to run you over or slash you with the mechanical claw. There are various items around the pillars, such as ammo and medikits of both sizes. When the floor plates start to drop out, watch your step as you keep battling Sabaoth. Once the battle is over, you can take the BFG.