Marvin Flumm was born in Watford City, North Dakota. As a mutant telepath of moderate ability, Mentallo was recruited by the original S.H.I.E.L.D. as a candidate for their ESP Division. Having been fired for cause after attempting a covert takeover of that organization, he has since operated as both a freelance criminal and a high-ranking agent of S.H.I.E.L.D.'s enemy HYDRA. Flumm is usually depicted as using technology to increase his power. He once had a longterm partnership with the Fixer. This partnership effectively ended when the Fixer was invited to join the Thunderbolts.
Mentallo once worked for the Red Skull and partnered with the Juggernaut in a successful attempt to get the Hulk to attack the Avengers. Mentallo managed to mentally impersonate the Hulk's wife-killing father and bully him into submission.
Under the name Think Tank, Flumm was a member of the Resistants, originally an incarnation of the Brotherhood of Evil Mutants. The Resistants opposed the Mutant Registration Act.
His most recent major role in the Marvel Comics Universe was using his telepathy as part of a conspiracy to break out of prison and acquire a device that would allow his employer to control all the supervillains who ever worked for Justin Hammer. Controlling the body of the villain Headlok, while Mentallo himself remained in prison, he freed several prisoners who came to be informally known as the Chain Gang. Hawkeye was included in the breakout, and led to the plan failing, following it up by forming a new team of Thunderbolts. He is one of the few mutants who retained their powers after the Decimation.
Mentallo is currently "working together" with MODOK and several other villains.
Powers and Abilities
Mentallo is a mutant with limited telepathic abilities, allowing him to read minds, control the bodies and minds of other humans, communicate telepathically and create illusions. He often uses scientific means (often provided by the Fixer) to enhance his telepathic abilities. He usually wears a special helmet to protect him against telepathic feedback, background noise and other telepaths. Mentallo also has the ability to send out mental probes to identify the shape and size of objects in his near vicinity, effectively creating some type of radar-sense. He can even locate invisible and intangible objects this way. As the Resistants member Think Tank, he used a small tread-propelled vehicle in which he sat, with his upper body and head still exposed. This tank unit was armed with a wide range of weapons - machine guns, grappler arms etc. - which Mentallo directly controlled with his telepathic ability and a special interface helmet.