WARNING: The following article contains major spoilers for Avengers: Infinity War, in theaters now.
The Marvel Cinematic Universe was tossed on its axis with the shocking cliffhanger at the end of Avengers: Infinity War. The Mad Titan, Thanos (played by Josh Brolin), successfully puts together all of the Infinity Stones needed for his Infinity Gauntlet, and with the powerful cosmic item now at his command, Thanos makes good on his threat to eliminate half the population of the universe and Bucky, Black Panther, Groot, Scarlet Witch, Falcon, Star-Lord, Mantis, Drax, Spider-Man and Doctor Strange all vanish from existence.
This ties into a promo that Marvel had released recently featuring Thanos snapping his fingers (Thanos snaps his finger earlier in the film, but do note that we don't actually see him snap his fingers when he kills off half the universe).
This is obviously a shocking turn of events and throws the future of the sequels of many Marvel films into chaos ahead of the release of the next Avengers film (the post-credits sequence also sees Nick Fury similarly fade into non-existence as he calls Carol Danvers, Captain Marvel, for help). However, for longtime fans of Thanos, this is paying off something that has been part of Thanos' back story for most of his history and was a major moment taken directly from the iconic Thanos-starring crossover event, Infinity Gauntlet. We'll explain the history behind this move, as well as show you how the scene was done in Infinity Gauntlet.
After introducing Thanos in the pages of his extremely short-lived run on Iron Man, Jim Starlin found himself with the opportunity of taking over Captain Marvel, the series starring the Kree warrior Mar-Vell, who had broken from his people to become the defender of Earth. Starlin took over the series with Captain Marvel #25 (initially working with co-writer Mike Friedrich) and in the second issue, he brought Thanos over to the series from his brief Iron Man stint to become the new main villain in the series. Thanos showed up at the end of Captain Marvel #26 and he brought with him a mysterious entity - the personification of Death itself!
We would soon discover what Thanos' plan was, that he was going to take over the Cosmic Cube, one of the most powerful items in the universe, all part of his mad quest to take over power of the universe itself.
The fascinating thing was that in these early issue, we don't see precisely why Thanos is so obsessed with his task. It is not until Captain Marvel #31 that he reveals his secret. He is not doing all of this out of some mad idea of hatred for the universe. No, in reality, this is all about his twisted love for Death and his desire to impress her. You see, Thanos had outright fallen in love with Death.
The problem with Death, for Thanos, is that she is a truly fickle mistress and she quickly abandoned him as soon as his battle with the heroes who had formed an alliance to stop him (the alliance included Captain Marvel, Drax the Destroyer, a being built specifically to stop Thanos, Moondragon, Thanos' brother, Eros, and his father, Mentor, plus the might of the Avengers) looked like it was not going to go the way that he expected...
Soon after, Thanos decided to prove his love for Death in a different manner. His Cosmic Cube plot had failed, so now he collected the various Soul Gems (what the Infinity Stones were called back then) and used them to power a sort of Cosmic Egg that he would use to destroy the Milky Way Galaxy, as he explained to the Thing in Marvel Two-In-One Annual #2 (also by Jim Starlin)...
However, it was not meant to be and instead, Thanos is killed by a time-traveling Adam Warlock and Thanos is turned into a statue and ends the comic in tears over his failure to succeed in his task for his love...