This article's content is marked as Mature
The page Mature contains mature content that may include coarse language, sexual references, and/or graphic violent images which may be disturbing to some. Mature pages are recommended for those who are 18 years of age and older.

If you are 18 years or older or are comfortable with graphic material, you are free to view this page. Otherwise, you should close this page and view another page.

Your duty has always been to die, soldier!
~ Sabaoth

Thomas Kelly, better known as Sabaoth, is a major antagonist in Doom 3. Formerly a human, Sabaoth is a result of the demon's corruption.

In both forms, Sergeant Kelly/Sabaoth is voiced by Neil Ross.


As a human, Sergeant Kelly has green eyes and a short patch of brown hair on his otherwise crew-cut hairstyle. For clothing, he wears a suit of green armor covering his chest and legs with boots, exposing his arms.

As Sabaoth, Sergeant Kelly's body changes into a nightmarish mixture of human and technological parts. On Kelly's head, right arm, and part of his torso is left unchanged, with a large mechanical claw serving as his left arm, a BFG 9000 strapped above his right shoulder, and his entire bottom portion being swapped for a tank-like frame serving as additional mechanical pieces.


Sabaoth is really Sergeant Kelly after his demonic transformation. He was at the top of the enlisted chain of command on the Mars Base (Marine HQ). Though stoic and cold, he is very well respected for his dedication. A career military man, he only expects the best from his men. He has a large pet peeve with lazy soldiers or slackers, often giving them awful tasks to due as penance.

Soon after finding Dr. Ishii, the demonic horde consumes the base, with Sergeant Kelly ordering his men to head to their HQ. Surprised at the player's survival, Sergeant Kelly asks you to link up with the Bravo Team to call for help. The player has the choice whenever to do so or not for this, be it obeying their commander or listening to Swann's concerns and not activating it. Although he asks for the player's presence at Service Tunnel 1, the transmission from the Service Tunnel 1 is the last we see of the sergeant uncorrupted.

How did Kelly become an abominable fusion of flesh and machine still remains unknown. While some believe Kelly was always in cahoots with the demons (as he wanted rescue to come to the Mars base, and him saying the hero's duty was to be slain), others suggest he was a heroic man only corrupted by Dr. Malcolm Betruger, and his attempts to summon the fleet were him innocently trying to get help.

Regardless, Kelly, not Sabaoth, attacks Swain and Campbell, eventually killing them both. The latter also warns of Sabaoth having the BFG 9000 on it.

The hero later comes face-to-face with Sabaoth, and with this form, the player is forced to kill Thomas Kelly, gaining the BFG 9000 after the fight.


  • Despite his absence in Doom 3: Resurrection of Evil due to his demise, the player can find his office. In it, the player can find the super shotgun and the arcade machine for Sarge's Big Game Hunt/Super Turbo Turkey Puncher 3, the latter depending on the version of the game.


           78-782068 doom-logo.png Villains

Cyberdemon | Former Humans | Icon of Sin | Kronos | Monsters | Mother Demon | Spider Mastermind | VIOS

Doom 3
Cyberdemon | Dr. Malcolm Betruger | Former Humans | Guardian of Hell and Seekers | Hell Hunters (Hell Time Hunter, Berserk Hunter & Invulnerability Hunter) | Monsters | Sabaoth | Vagary

Cyberdemon | Dark Lord | Doom Hunters | Former Humans | Gladiator | Hell Guards | Hell Priests (Deag Grav, Deag Ranak, Deag Nilox) | Icon of Sin | Khan Maykr | Marauders | Maykrs | Monsters | Night Sentinels | Olivia Pierce | Order of the Deag | Samuel Hayden | Spider Mastermind

Doom: Dr. Todd Carmack | The Infected | Sarge
Doom: Annihilation: Demons | Demon Overlord | Dr. Malcolm Betruger

Community content is available under CC-BY-SA unless otherwise noted.