Thanos is a member of the Eternals, a race of genetically advanced human offshoots, born on the moon of Titan. He was born with Deviant Syndrome, causing his grotesque, massive appearance, which led to his mother trying to kill him and him becoming an outcast.
His world was destroyed by overpopulation and resource depletion. After his solution—randomly killing half the population—was rejected by his people, he watched his world collapse. His cosmic quest is fueled by a belief that overpopulation is destroying the universe and his mission is to save it by wiping out half of all life. With the Infinity Gauntlet he possessees.
