What The Avengers: Infinity War Cast Look Like In The Comics

In the Comics:

A megalomaniacal figure literally in love with Death, Thanos was born with a condition that gave him hard, purple skin where his siblings looked human-like, and beautiful. Mistress Death convinced him to lose his fear of killing in childhood, and he eventually he became a supreme destroyer of all things, using the Infinity Gauntlet and its Gems to kill half the universe to please her.

In the Film:

More motivated by personal loss, Thanos in Infinity War wishes to wipe out half the universe in order to save those left from extinction - a fate which befell his home planet, Titan.

In Infinity War, Thanos retrieves three Infinity Stones (wiping out Xandar and killing Loki in the process), before sacrificing Gamora for the Soul Stone. He faces off with the heroes on Titan, nearly killing Tony Stark, before Doctor Strange exchanges the Time Stone for his life. With five Stones, he goes to Earth, taking the Mind Stone by force. With a snap of his fingers, he wipes out half of all life in the universe, for the first time finding peace after his crusade.

He's portrayed by Josh Brolin in Infinity War. Though his motivations differ, he still strongly resembles his comics counterpart.