The one man army villain

Thanos, a warlord from Titan who aim at bringing peace and stability to the whole universe as he believed that it would be impossible for his massive population to drain all the universe's supply of resources and condemn it.
To complete this goal, Thanos tracked down all the Infinity Stones which would result ineliminating half of the universe population.
Thanos had a great vision and he forged alliances with Loki and Ronan the Accuser in order to complete his mission in tracking down some of the Stones but turns out to be a bad idea and he had to pay the consequences including the Mind Stone and the loyalty of his daughters, Gamora and Nebula.

As Thanos was fed up with all his continuous failures, he forced Eitri to create the Infinity Gauntlet for him, while Thanos then opted to seek out the location of the six Infinity Stones himself.

Thanos engaged in an intensive mission of finding all the infinity stone by himself in all corners of the universe. During his mission, Thanos togerther with his Black Order invaded multiple planets and slaughtered thousands to gain the stones, including Loki and the Asgardians. He even sacrificed his beloved Gamora to take the Soul Stone.

Thanos soon found himself challenged by an alliance comprising the universes greatest teams, The Avengers and Guardians of the Galaxy. However, despite facing off against the powerfully combined opposition and the wrath of Thor, Thanos still ultimately triumphed and completed the Infinity Gauntlet, using it to finally complete his goal and had caused the Decimation, resulting in half of all life in the universe being wiped out at the snap of his fingers.

Three weeks after the Decimation, Thanos was ambushed on his farm on Titan II, where he revealed that he had destroyed the Infinity Stones to ensure the Decimation's success. At this revelation, he was promptly decapitated by Thor.