Although "X-Men: Apocalypse" is still in theaters, speculation has already turned to who Fox's mutants will face in the sequel. Whether they head to space or remain grounded, Marvel's Children of the Atom have a deep bench of villains from which to pull.
"Apocalypse" director Bryan Singer and screenwriter Simon Kinberg want to make good on their promise to redeem the "Dark Phoenix Saga" storyline on film, but even if they choose to head down a more original path, the X-Men will need some mythic villains to test their mettle. With the timeline reset following "Days of Future Past", and classic mutants reintroduced to the cinematic universe, the stage is set for old villains to be reimagined as well. While we wait for new details to emerge about the future of the X-Men franchise, these are the villains we could envision wreaking havoc on the big screen.
7 Mister Sinister
After watching "X-Men: Apocalypse's" post-credits sequence, the X-Men's movie universe looks a great deal more ... Sinister. Essex is the name belonging to Mister Sinister, an immortal scientist born in the Victorian era who became a geneticist obsessed with mutants and cloning. He has deep ties to both Apocalypse and Scott Summers, meaning there's plenty to build on if Nathaniel Essex arrives in the next film. The mad scientist could bring an element of horror to Fox's superhero universe, giving the X-Men an iconic and modern movie monster. Where Sinister goes in the comics, huge storylines often follow, and there's always a chance they could land "Breaking Bad's" Bryan Cranston after the actor expressed interest in bringing this Machiavellian X-foe to life.
Nothing stops the Juggernaut, and even the mishandled version of the character played by Vinnie Jones in 2006's "X-Men: The Last Stand." But there's a lot more to Cain Marko than bad one-liners and a suspect costume. In addition to becoming an unstoppably powerful force thanks to the Crimson Gem of Cyttorak, Marko is also Charles Xavier's stepbrother (a fact completely ignored by his previous film appearance). Juggernaut could act as the X-Men's version of the Hulk, with power and fury rivaling Bruce Banner's alter ego -- only he's a villain. Despite his often criminal ways, Juggernaut has always been depicted with shades of grey, a complex powerhouse of both immense power and fascinating personal vulnerabilities.
With characters like Toad, the Blob, Lady Deathstrike and Viper, Fox has found great side roles for some of Marvel's more esoteric mutant villains. With multiple sequels and solo films still planned, there's always room for at least one more, and Mesmero is one of the most colorful villains in mutantdom. Don't let his gaudy appearance fool you, Mesmero has the power to control other mutants' minds and has been a deadly foe since the Silver Age. His signature green skin and frightening are somewhat reminiscent of Kilgrave, the Purple Man, who haunted viewers and the protagonist in "Marvel's Jessica Jones." Mesmero has been used as a pawn of Magneto in the past, providing another potential entry point for Fox needs to make this criminally underutilized villain into the X-Men's next big screen threat.
If you stuck around for "Deadpool's" post-credits scene, you know Cable is on his way to the big screen in the sequel. There's a good chance the actor who takes on the iconic role could be playing "Orphan Black"-style double duty as both the time-displaced mutant and his evil clone raised from birth by Apocalypse. Fans were stunned when this X-baddie took off his helmet and had a face that looked exactly like Cable, and that same shocker could be in store (for the uninitiated) on an even bigger scale on film. Clones, time travel, and some serious evil could be just the ticket for the next X-Men movie, and there's always the chance he could arrive in "Deadpool 2" or the long-gestating "X-Force" movie where Cable is also expected to play a pivotal role.
3 The Marauders
With the criminal cyborg squad the Reavers reportedly appearing in "Wolverine 3," there's always the opportunity to introduce a whole team of villains to battle the X-Men. The Marauders are a mercenary team of mutant assassins charged by Mister Sinister with wiping out genetic imperfections in mutantkind. They took center stage in the "Mutant Massacre" crossover, planning and executing an attack on the sewer-dwelling Morlocks resulting in the genocide of a group of mutant outcasts. With villains as dangerous as Sabretooth, Wolverine's hated arch-rival, a member of this kill crazy merc squad, the Marauders could create a serious threat for the X-Men and perhaps strike up some brand new rivalries for the newly assembled X-Men.
2 Black Tom Cassidy
Black Tom Cassidy has the power to channel heat blasts through wood (usually a shillelagh), but it isn't his powers alone that make him fit for the big screen. His best pal is Cain Marko, AKA Juggernaut, and they've enjoyed one of the longest running villainous friendships in comics. Most bad guy partnerships end in betrayal because, well, bad guys. But Juggernaut and Black Tom are the exception that proves the rule. They're incredibly loyal and stuck out their own necks to safeguard the other time and again. This dynamic isn't something that's been seen in the recent wave of superhero films, and Tom might have an added reason to attack the X-Men -- his brother Banshee was killed (offscreen) after joing of Xavier's team.
While his powers of illusion were borrowed by Jason Stryker in "X2: X-Men United," the resetting of the timeline following "Days of Future Past" mean the stage is set for Mastermind to show up on screen in earnest. Mutant mentalist Jason Wyngarde was one of the earliest evil mutants introduced by Stan Lee and Jack Kirby, an original member of Magneto's Brotherhood and one of the X-Men's slimiest and most immoral foes. In fact, it was Mastermind who manipulated Jean Grey into believing that she was his lover and it was this perverseact that pushed her into becoming the Dark Phoenix as she took revenge against him. With producer/screenwriter Simon Kinberg saying he wants another shot at Dark Phoenix following "The Last Stand," following the comics' lead and using Mastermind to push Jean down a dark path could be exactly what's called for.