Thanos

"If you fail, if the Tesseract is kept from us, there will be no realm, no barren moon, no crevice where he can not find you. You think you know pain? He will make you long for something as sweet as pain."

- The Other describing Thanos Thanos is a supervillain from Marvel Comics. He debuts in a brief appearance during the closing credits of the 2012 Marvel action film The Avengers and is formally introduced as a long–term background villain in Guardians of the Galaxy.

Thanos is portrayed by actor Damion Poitier in The Avengers, and is voiced by Josh Brolin in Guardians of the Galaxy and in Avengers: Age of Ultron.

The Avengers
The Other tells Thanos that the Tesseract is in a small world, a human world. It also informs him that Loki is ready to lead the Chitauri. In a post-credits scene, Thanos is revealed to have been Loki's benefactor, having provided the Chitauri army used by Loki in his attempted invasion of Earth. When advised by his intermediary (known simply as the "Other" ) that opposing the Avengers would be "to court death," Thanos glances at the camera and flashes an evil grin.

Guardians of the Galaxy
Thanos plays a more active role in the film, where he has enlisted the help of Ronan, Korath, and his daughters, Gamora and Nebula, to retrieve the Orb for him. As it turns out, Gamora is not actually Thanos' daughter, since Thanos killed Gamora's family and snatched her as an infant to train her into the perfect assassin, having abused and tormented her in the process of doing so. This causes Gamora to betray Thanos, which leads to a chain of events that leads to Gamora finding her true calling as a protector of the universe and a member of the Guardians of the Galaxy.

When Ronan and Nebula are called to discuss Gamora's betrayal, Ronan kills The Other, who was speaking for Thanos. Thanos does not react to this but is angry at Ronan for not obtaining the Orb (and for apparently alienating Gamora). He says he will destroy Xandar for Ronan if he brings him the Orb, and will kill him if he does not.

Thanos promised Ronan that he will help Ronan destroy Xandar in exchange for Ronan's services. However, once Ronan gets ahold of the Orb, he feels he no longer needs Thanos help and also decides to betray him. Nebula also decides to betray Thanos out of jealousy over Thanos showing preference for Gamora over her. Ronan and Nebula take Korath with them. In the end, Ronan and Korath are killed by the Guardians of the Galaxy (including Gamora), Nebula escapes and becomes a renegade villain independent of Thanos, and the Guardians give the Orb to the Nova Corps for safekeeping.

Thanos, however, is still determined to find the six Infinity Stones and the Infinity Gauntlet so he can use them to conquer the universe.

Avengers: Age of Ultron
In the mid-credits scene, Thanos retrieves the Infinity Gauntlet from a vault and heads off in search of the Infinity Stones himself after the failings of Loki and Ronan the Accuser.

Avengers Assemble
At the end of the episode "The Final Showdown", Thanos is revealed to be Red Skull's master as Red Skull gives him the Tesseract. In the final moments of the episode "The Arsenal", Thanos comes to Earth in search of the Power Stone.

In the episode "Thanos Rising", after attacking the headquarters of Uatu, Thanos shoots down an Avengers Quinjet. After falling into a trap of the Avengers, Thanos confronts the Avengers, Thanos wins easily but Arsenal hits him with the power of the Power Stone. However, Thanos reveals that is in possession of the Infinity Gauntlet and takes the stone from Arsenal.

After Thanos is hit to the other side of the galaxy when Arsenal unleashes the power absorbed by the stone.

Quotes

 * "The only matter I do not take seriously, boy, is you. Your politics bore me! Your demeanor is that of a pouty child. And apparently you alienated my favorite daughter, Gamora. I shall honor our agreement, Kree, if you bring me the orb. But return to me again empty handed and I will bathe the star-ways with your blood." (to Ronan)
 * "Boy! I would reconsider your current course."
 * "Fine. I'll do it myself."