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Doctor Mobius is a think tank operating in the Big MT in 2281. He is the leader of the robo-scorpion army and nemesis of Dr. Klein and the team to which he belonged.


Doctor Mobius was one of the Big MT "Think Tank" executives before the Great War. Sometime after the War, he became a think tank in order to continue his work at Big MT. Like the others, he forgot a part of his personality and his real name, due to the recursion loop in their new perception programming.

After the escape of the cazadores and night stalkers, Mobius became disillusioned with the methods of the other think tanks. He grew tired of the endless and horrible experimentation and was deeply afraid of the damage the amoral and psychosis-ridden think tanks would wreak upon the fragile, post-apocalyptic world in the name of science. He erected a radar fence, a kind of radar-guided repulsive field, around the perimeter of Big MT to prevent the disembodied brains from escaping into the wasteland.

After a severe dispute with Klein, Mobius removed all the chips of all personalities of The Sink; his room and personal laboratory, and against their will, hacked the data banks of his colleagues, reprogramming their chronometers, geometers and cartography programs, making them lose their sense of history, time and the world beyond Big MT to the point that they now believe Big MT is the world and nothing exists beyond its mountainous boundary. He also actively fostered the false notions that robo-scorpions are somehow able to consume intelligence from brains, fueling the Think Tanks' fear of leaving Big MT's central dome. In the process of making these alterations, though, he also damaged some of their memories and knowledge, leaving only mangled, disjointed versions behind. Disgusted to have done this to his friends, he also erased some sections of his own memory, like this event and his pre-War creation, the robo-scorpion, before exiling himself.

Afterward, Mobius moved to the X-42 robo-warfare facility (which he renamed the "Forbidden Zone") and began to "recreate" the robo-scorpion, inspired by radscorpions that had wandered into Big MT. These new versions included all features of the pre-War model, such as an energy bolt blaster in the tail, highly sensitive robotic eyes, and communication systems connected directly to his stronghold. Now in possession of a proper army, Mobius decided that without something to distract the other think tanks, the radar fence would eventually become insufficient to contain them. He began to send repetitive, threatening broadcasts, designed to instill fear and prompt the think tanks to focus on retrieving technologies with which to defend themselves. With the remaining think tanks trapped in the central dome by their exaggerated fear of Mobius, the Big MT fell mostly silent.

Although not originally aggressive in his intentions, Mobius' own behavior seems to have degraded over the years, likely in part due to an increasingly serious addiction to Mentats and Psycho. By 2281, he had not only lost the functionality of his right "eye" monitor but also began to suffer from short term memory loss, hallucinations and obsessive-compulsive behavior. Although his plan had been mostly successful, the recent arrival of Father Elijah, Christine and Ulysses from the Mojave has caused the curiosity of the think tanks to begin pushing beyond the boundaries he had set for them.

The arrival of the Courier, and the subsequent survival of their lobotomy proved to be the last straw. Mobius unleashed a fresh wave of robo-scorpions and announced his false intention to finish the other think tanks off once and for all, while subliminally suggesting to them that various technologies around the Big MT would help them against him. These technologies, a sonic emitter, an X-2 antenna, and a Stealth suit Mk II are actually all the components required to rehouse a brain inside a body. Eventually, the Courier defeats the X-42 giant robo-scorpion, enters the Forbidden Dome and confronts Mobius.

Interactions with the player character

Interactions overview

FO76 ui icon quest.png
This character is involved in quests.


  • Old World Blues: The player character is to go to Mobius' lair and either kill him or reason with him.

Other interactions

  • If the player character has a repair skill of 75, this allows them to repair the "ghosting" in Mobius optical sensors. This will open up the conversation to leave him be without having to kill Mobius.
    • If the player character cannot perform the 75 repair check, they will be forced to kill Mobius, as the conversation can only end with "enough, I came here to kill you."
  • He will offer the Courier a tin of Mentats upon interacting with him through dialogue, once per 24 hours.
    • If one has consumed alcohol and Mobius asks them if they would like a Mentat, they may turn it down saying that they would rather avoid mixing it with alcohol.
    • If one is already addicted to a drug when he asks them if they want some Mentats, they can refuse, stating that they are tripping as it is already.

Fighting Mobius

  • If the player character says that they think they're going to kill him, Mobius claims he's never been killed before (obviously true), and that he's eager to see how it goes. He will still fight back and summon his robo-scorpion army, though.
  • Once combat is entered, Mobius will activate a Stealth Boy, this making it impossible to target him in V.A.T.S.
  • Dr. Mobius has significantly more health than the other Think Tank members, and along with Doctor Klein is the only Think Tank that levels with the player character.
  • The player character cannot yield to Mobius. The decision to assault him is final.


Apparel Weapon Other items On death
Brain beam
Brain mesmetron
Electron charge pack
Stealth Boy
Fission battery
Scrap electronics
Scrap metal
Sensor module


  • Mobius has a tendency for malapropisms. For example, instead of saying "reason," "quite" and "desert," he'll say "raisin," "quiet" and "dessert." He also struggles to differentiate between other words and names, such as "custard" and "mustard".
  • Mobius programmed the Sink Central Intelligence Unit to accept bottle caps. Dr. 0 believed they were added in as debug code, though Dr. Dala states that Mobius was obsessed with what the post-nuclear war economy would be like, and correctly predicted that bottle caps would become valued currency post-war.
  • Mobius refers to tripping on Psycho and Mentats. This can be seen in the upper rooms of the Forbidden Zone dome, which contains both samples of Psycho, and an extremely large supply of Mentats.
  • He appears to be a fan of Nuka-Cola, as many empty Nuka-Cola bottles and paraphernalia can be found in his old room in both the Think Tank and Higgs Village.
  • He was responsible for the creation of all of The Sink intelligences, except for Muggy, who was created by Dr. 0.
  • He has the most damaged and rusted body, compared with other Think Tank members.

Notable quotes


Mobius appears only in the Fallout: New Vegas add-on Old World Blues.

Behind the scenes

  • Mobius was inspired by Dr. Edward Morbius, the antagonist in the 1956 science fiction film Forbidden Planet, as well as the name of his base.[Non-canon 1]
  • His name is also a direct reference to the Möbius strip or Möbius band, a 3D object which topologically has only one side.
  • If the player character has taken the Wild Wasteland trait, Mobius will mention keeping several "Plan 9s in place."[1] This is a reference to the cult-classic, 1959 science fiction/horror film Plan 9 From Outer Space.
  • Frank L. Baum's book, The Wizard of Oz, is referenced by both a line of dialogue and a script note in Mobius' dialogue.[2]
  • The spiritual song "Dem Bones" is referenced by both a line of dialogue and a script note in Mobius' dialogue.[3]
  • His farewell dialogue "Please mind the equations on the floor"[4] is a nod to a Greek scientist and engineer Archimedes, who was killed by a Roman legionary during the Second Punic War, purportedly because he angrily shouted to the legionary who unintentionally stepped over his mathematical writings on the ground, "Do not disturb my circles!"
  • If asked about a non-violent way to deal with the Think Tank, Mobius will suggest appealing to their humanity, mentioning how "A wise man once said that the eyes do more than see".[5] This alludes to the short story Eyes Do More Than See by Isaac Asimov.



  1. The Courier: "Why did you trap them?"
    Doctor Mobius: "I suspect I have Plan 9s in place, but I may have coded myself to forget them, just in case... they're probably very dangerous, lethal, or worse. So I had to do something else to keep them occupied here. Or as you like to say "trapped." I prefer to have several Plan 9s in case the 7s fail."
    (Dr. Mobius' dialogue)
  2. Doctor Mobius: "In short: Brains, a heart, and courage... spine. I think there was a story once where a band of murderous thugs sought these things."
    (Dr. Mobius' dialogue)
  3. Doctor Mobius: "Electron's attached to the... neutron. The neutron's attached to the... meson. Meson's connected to the... proton.
    (Dr. Mobius' dialogue)
  4. The Courier: "Time for me to go. Goodbye."
    Doctor Mobius: "Indeed, the uh... goodbye part of our little chat, then. Uh... Goodbye. Please mind the equations on the floor."
    (Dr. Mobius' dialogue)
  5. Doctor Mobius: "...a wise man once said, the eyes do more than see. Make them see, if you can."
    (Dr. Mobius' dialogue)