She-Hulk: Attorney at Law spoke for MCU fans everywhere when she asked K.E.V.I.N. when the X-Men will finally appear. Their MCU debut remains a mystery, but inevitable. Only one question remains at this point, and that is which members will make up the team. MCU fans looking for clues in the comics may be surprised to find several villains could fill out the roster.
Villains becoming heroes arguably serves as a major trope in X-Men comics, with thin lines separating heroes like Professor X and villains like Magneto. That line all but dissolved in the Krakoan era, with numerous former villains serving on the White Council alongside X-Men. No doubt some villains serve on the first MCU X-Men roster, including some iconic characters.
Rogue
Rogue counts among the best X-Men characters ever, but she started as a villain. She debuted in Avengers Annual #10, a monumental issue where she fights the Avengers alongside the Brotherhood of Evil Mutants. She steals Carol Danvers' powers and memories in the process, changing both their lives forever.
Rogue struggled with her newfound powers and ultimately turned to Professor X for help. Though the X-Men resisted her at first, she eventually became an integral member of the team.
Juggernaut
Juggernaut reliably serves as an X-Men villain going back to his iconic first appearance in The X-Men #12 in 1965. He plays that role in various media as well, including the best X-Men: The Animated Series episodes. He may work as a hero in the MCU as he fought alongside his former enemies in the 2000s and beyond.
Juggernaut joined New Excalibur and worked with the X-Men to expose the New Brotherhood of Evil Mutants during this period, complicating his legacy as a stalwart villain in the X-Universe.
Deadpool
Deadpool 3 likely serves as the X-Men's first major foray into the MCU thanks to Hugh Jackman returning as Wolverine. Deadpool also represents a major villain who became a hero. He began as a mercenary, debuting in The New Mutants #98, fighting that team and later X-Force before his character evolved considerably.
Deadpool gradually transformed into an antihero who fought alongside the X-Men and other Marvel Comics heroes to save the world and sometimes the universe, as he probably does in the MCU.
Sabretooth
Sabretooth makes a case for being the most evil X-Men villain in the comics. Vile, violent, and unstoppable, he numbers among the few villains without any redeeming qualities. But in Age of Apocalypse, a seminal storyline set in an alternate universe, Sabretooth became a heroic X-Man.
Sabretooth joined the X-Men and mentored Blink, a young mutant, proving that given the circumstances, he had the potential for good. This version seems unique in the comics, however.
Apocalypse
Apocalypse instigates the dystopian alternate timeline by killing most people on Earth. His ambition for only the strongest to survive always cast him opposite the X-Men and their extended family, but in recent years, the ancient mutant became a foundational member of the new order established on Krakoa.
Apocalypse served on the White Council and contributed to the establishment first of Arrako on Earth and then the Martian colony. His Darwinian ethos even seeped into the X-Men's logic, as he began holding combat trials on the island that sought to empower mutants through death and resurrection.
Mystique
The shapeshifting villain Mystique led the Brotherhood of Evil Mutants against the X-Men numerous times. She also fought other Marvel Comics heroes like Carol Danvers, as she did in her first appearance in Ms. Marvel #18. For many years though, Mystique walks a fine line between good and evil.
Mystique served as a secret agent for Professor X in the early 2000s and again on Krakoa, carrying out highly sensitive missions. She recently joined the White Council. engineering a coup to install her wife Destiny and out Xavier in the process.
Quicksilver
Quicksilver helped inaugurate the Brotherhood of Evil Mutants in The X-Men #4 in 1964 alongside Magneto, The Scarlet Witch, and The Toad. He fought the X-Men with his incredible speed, which makes him among the fastest X-Men in Marvel Comics. He quickly abandoned his evil ways, however, and joined the Avengers.
Like the rest of his complicated family, Quicksilver runs back and forth between hero and villain. His ego and pride tend to tilt him in the villain direction, but his history mostly aligns him with the X-Men and the Avengers.
Scarlet Witch
The Scarlet Witch debuted along with her brother in The X-Men #4 but challenged her role as a villain from the start. She also followed Quicksilver into superheroics in Avengers #16, joining the team she remained part of for decades. She later turned evil again, as fans know full well from her actions in House of M.
Wanda spent years making up for erasing most mutants from existence in that epic story and now serves as a powerful guardian for mutants and the world after magically creating a mutant afterlife.
Magneto
Comic book fans know Magneto began as the quintessential X-Men villain. In many respects, he serves as the quintessential X-Men character. His journey from villain to complicated antihero to outright superhero forms the backbone of nearly sixty years worth of comic book, movie, and television stories.
Magneto led the X-Men in various comic book storylines in and out of continuity and most recently served on the White Council. Though he and the X-Men started with differing views, their perspectives now mostly align.
White Queen
Emma Frost stormed onto the stage in Uncanny X-Men #129 as the White Queen. She and The Hellfire Club proved challenging villains for the X-Men and it might surprise casual fans she now effectively rules the White Council and by extension, Krakoa. Her journey from villain to hero ranks up there with Magneto.
Emma gradually drifted into heroism over several years. She helped run Xavier's School For Gifted Youngsters in the 1990s and then joined the X-Men in the 2000s. Since then, she consolidated power and influence, even winning over X-Men who always disliked her, like Kitty Pryde.