In the Marvel Comics universe, Master Mold is the controlling artificial intelligence behind the Mark One Sentinels. Created by Dr. Bolivar Trask, Master Mold's purpose was to construct and command an army of Sentinels to surpress the mutant population of the USA. It would soon come to the conclusion that in order to eliminate mutants, it would have to subjugate humanity so as to prevent new mutant births. It was believed to have been destroyed after its first battle with the X-Men, but would survive and return on several occasions to threaten mutants and humans alike.
Master Mold was created, by Bolivar Trask, to build an army of Mk I Sentinels to control the mutant population. However, this version was damaged when the Sentinel Headquarters was destroyed by the X-Men.
After Trask's death, the government of the United States put the Sentinel operation under the command of a Stephen Lang, a mutant-hating bigot who began reconstructing Sentinels with Trask's notes for his own goals. The Inner Circle of the Hellfire Club provided him with funds, not knowing that he wanted to kill all the mutants. Lang rebuilt the Master Mold, but did not use it.
During a battle against the X-Men, they destroyed the space station where Lang and the Sentinels were. Lang was lobotomized, but his memory-engrams were printed in Master Mold's computers. Thus, Master Mold suddenly believed that it was Lang himself.
Surviving the explosion, Master Mold built a new base on a near asteroid and then went to Earth to capture Angel and Iceman. Master Mold also, accidentally, captured the Hulk. The three heroes managed to escape their prison and the Hulk severely damaged Master Mold. Master Mold tried to blow away the station to destroy the mutants, but the mutants and the Hulk managed to escape.
The damaged body of Master Mold fell into the sea, off the coast of Alaska. Using its reconstruction facilities, the wreckage from an oil platform, and sunken ships, Master Mold was again complete and detected X-Factor leader, Cyclops, in Anchorage, looking for his missing wife and son. Master Mold attacked him, but Cyclops tricked him into shooting gas storage tanks. The resulting explosion destroyed Master Mold's body, again, but its brain module survived.
Somehow, Master Mold reached Muir Island and mind controlled Dr. Moira MacTaggert. Master Mold then made her create the Retribution Virus, which stopped mutants from using their powers and then killed them. However, Dr. MacTaggert's lover, Banshee, noticed something wrong and called Cyclops for help. Cyclops went to Muir Island and Master Mold tried to kill him twice, but failed.
Master Mold infected Banshee and a mutant girl with the virus, and then captured them. Cyclops tried to stop Master Mold's robots from taking them away, but was then defeated. However, he managed to rescue Dr. MacTaggert from the mind control. Dr. MacTaggert then tried to research for a cure, but Muir Island was then invaded by Master Mold's robots, which were led by an special robot, Conscience, which was programmed with Lang's memory-engrams and a skill to feel emotions. Dr. MacTaggert, Cyclops, and his ally, Callisto, were defeated by the robots, infected with the virus (except for Dr. MacTaggert), and taken to Master Mold.
Master Mold and the Conscience discovered that the virus had mutated and also killed normal humans. Master Mold insisted on using it anyhow, assuming that a small number of normal humans would survive that could be controlled to avoid the birth of new mutants. However, Conscience, being emotional, decided that it would be unfair and apparently destroyed Master Mold, and later itself, to avoid the use of the virus.
Somehow Master Mold survived and then fought Power Pack and the X-Men, before merging with the advanced Sentinel Nimrod and being forced into the Siege Perilous.
- Superior Strength - The enormous Master Mold robot possesses tremendous strength. Its limits are unknown but variable between its different bodies.
- Sentinel Construction - Versions of Master Mold have shown to be capable of building new Sentinels within its own body.
- Mutant Detection - Like the Sentinels it commands, Master Mold can detect the X-gene within humans and recognise them as mutant.
- Weapons - Master Mold has been armed with lasers and other energy beams, as well as homing missiles and freeze blasts.
- Mind Control - Master Mold has demonstrated that it is capable of conditioning individuals into serving its own purposes.