When his race had engaged the Gigantians in a war about to lead to mutual absolute destruction, Grom was chosen for his physical prowess as the receptacle for their entire population of several hundred million minds.
The Overmind mentally enslaved both the Squadron and that Earth's leaders while posing as the U.S. president Kyle Richmond, and began construction of an interstellar armada to invade other worlds.
Meanwhile, Null had leeched away the Overmind's mental energies, but yet another psychic composite entity of seven human telepaths empowered by the assembled heroes, defeated him and inhabited the weakened Grom.
He tried to find a purpose by attempting to help Millwood, New Hampshire, a town of 800 people dying of chemical poisoning, by controlling their minds to foster the illusion that they were well.
[10] The Overmind's future counterpart travels back in time to present-day Squadron-Earth to aid the Scarlet Centurion in repelling the expanding Nth Man.
He was eventually located by Baron Zemo and his Thunderbolts, during the Civil War event, and coerced to join the group or face jail time.
The Overmind possesses vast psychic powers derived from the synthesized intellects of the billion Eternals of Eyung composing his essence, including telepathy, telekinesis, or illusion-casting, and can use them over great distances.
As a result of his alien physiology and metabolism, he possesses great superhuman physical strength, magnified sevenfold through psionic augmentation; and even more impressive speed, stamina, and durability.