Since the release of Avengers: Infinity War and it's epic conclusion Avengers: Endgame, Marvel's biggest bad guy has become just as universally synonymous with the word evil as Darth Vader or even the Devil, but to the fans of the comics from which he came, they known Thanos has a lot more to offer. While it may seem hard to believe, Thanos actually once teamed up with one of Marvel's best do-gooders, Professor Charles Xavier, to help save the universe in a mini series event known as The Infinity Crusade.
Starting with its first issue featuring a story titled Epiphany, published in June, 1993, the mini series event ran across a total of six issues. The mini series gathered together fan favorites across the entire Marvel Comic Universe and centered around a villain known as the Goddess.
When the Goddess gathers 30 Cosmic Containment Units, she is able to merge them into the Cosmic Egg and use it to form her own planet, Paradise Omega. This planet then becomes her home base as she sets out to eliminate all evil in the universe, and she calls upon heroes from across it to defend her as she charges inside of the egg. Unfortunately for the universe, good cannot exist without evil, so if she succeeds in wiping out all evil, she will in turn wipe out all of existence as a whole, something the heroes she manipulates into helping her are unaware of. As the remaining heroes of Earth begin to gather, they start to piece together what is going on. Iron Man, Vision, and Mister Fantastic attempt to go to Paradise Omega, only to be attacked by Moondragon and other brainwashed heroes. When Professor X attempts to use his telepathic abilities to contact Moondragon, he is met with a telepathic attack that leaves him in a coma.
Meanwhile, Adam Warlock realizes that much like the Magus had been his "evil" side, the Goddess is his "good" side. After rescuing Thanos from the Goddess's attack, the two make a deal with Mephisto, trading his knowledge about the Goddess in an exchange for a promised Cosmic containment unit. Thanos sets off to help the remaining heroes of Earth, and on his way is able to convert the Silver Surfer back from the grasp of the Goddess.
Charging his power beyond its limits, the Silver Surfer is able to focus massive energy into a charged attack on Paradise Omega, taking out its defenses and allowing the heroes of Earth to land. A massive battle breaks out between heroes on both sides, those fighting to take down the Goddess, and those brainwashed to defend her. Now this is where the Thanos and Professor X team up really kicks in. As the rest of the heroes duke it out, Thanos uses the comatose Professor to help boost his own telepathic powers. With their power combined, they are able to direct the Goddess directly. Unfortunately, it seems too late, and all life in the universe goes up in flames. Thankfully, it is quickly revealed that this is simply an illusion by Adam Warlock, an illusion that allows the Goddess to think she succeeded just long enough for Thanos, Professor X, and Warlock to deliver the final blow. Using their combined powers, they are able to capture her soul, and ultimately trap it within the Soul gem.