Sure, X-Men: Days of Future Past was a pretty massive movie with some new mutants to show off, but let's be real: the spotlight was totally on the established cast with the exception of Evan Peters as Quicksilver.
But that's probably about to change with X-Men: Apocalypse, which screenwriter Simon Kinberg claims will be a far bigger movie than DoFP. Kinberg has also stated that they want to stay away from "alternate timelines" in an attempt to make "Apocalypse" something new and different.
"Because it takes place years after Days of Future Past, there’s an opportunity to start to tell origin stories of other characters we haven’t told yet."
Well, even after seven movies, there are plenty of X-Men characters who still haven't made their big screen debut. Here's just a handful of them:
Yes, yes I know Jubilation Lee was technically in the first three X-Men films as a student. But her powers (shooting energy plasmoids) are never actually seen, save for a deleted scene in X2. For all intents and purposes, this new retcon set by DoFP warrants a true origin story for this character, who could be presented in "Apocalypse" as a very young girl.
Again, this is a character that was already introduced in X-Men: The Last Stand, but he was still "Angel" at that point. Warren Worthington III is destined to eventually become Archangel, and having him join the X-Men in "Apocalypse" makes perfect sense as he is one of the founding members in the comics.
Story-wise, all you have to say is that due to the retcon of DoFP, Warren's parents birthed him earlier to provide an heir to their fortune, believing that the world is ending due to mutants. By the 80s, Warren would be a teenager beginning to realize he has powers. Ultimately, this would give Fox the chance to present a "better" version of Angel: the arrogant playboy we know from the comics.
Later, after becoming a tool of Apocalypse, Angel becomes "Archangel," a colder, more brutal version of himself that we have yet to see in the movies.
#3 Scarlet Witch
Thanks to the popularity of Quicksilver in DoFP, the introduction to his twin sister, Wanda (AKA Scarlet Witch), is pretty much a given. A fantastic side story to the "Apocalypse" narrative would be to have Magneto recruit his kids to the Brotherhood, along with...
OK, introducing Peter and Wanda's half-sister might be too much, too soon, but Lorna Dane (Magneto's bastard daughter) is definitely a mutant we've been itching to see, green hair and all. I wouldn't be surprised, however, if Fox decided to just go with an X-Men spinoff that would center around the three kids.
#5 Mister Sinister
Technically, Sinister is kind of an "artificial" mutant. In the 1800s, he was genetically altered by Apocalypse to have a long lifespan and the ability to add the DNA of other mutants to his own, thus giving himself a wide array of powers. Therefore, having him show up in "Apocalypse" is a no-brainer, especially if Fox truly wants to make an X-Force movie. After all, you can't have the X-Force without...
You see, Cable (the future leader of X-Force) wouldn't exist if it wasn't for Sinister, who orchestrated the birth of Nate Summers, the child of Jean and Scott (it's actually way more complicated than that, but I doubt "Apocalypse" will include all of the cloning parts of the backstory). Sinister expected a powerful mutant to be born from Jean and Scott, and he was right, as Cable has immense psychic abilities.
My guess is that the birth of Cable will be alluded to in "Apocalypse" with the child being briefly shown in the post-credits to tease an "X-Force" movie.
It would be great to see Domino (AKA Neena Thurman) in her early days before eventually joining X-Force. A possible storyline would be for the government to devise Project: Armageddon in an attempt to combat the powerful Apocalypse. This would also mean, of course, that we would meet Beatrice, a precognitive mutant who was used to genetically engineer powerful mutants like Domino, who uses probability to create acts of both "good" luck and "bad" luck to defeat her enemies.
I'm probably getting greedy with potential X-Force characters, but Cannonball is also a mutant with ties to the X-Men and many other affiliations, including the Hellfire Club. In fact, his name shows up on Stryker's computer during X2, proving that Sam Guthrie is somewhere out there in the movie universe.
Sam is able to release thermochemical energy as a propulsion that gives him flight and makes him impossible to stop. He was originally part of the New Mutants back in the 80s (perfect for "Apocalypse"), but he was later added to the X-Force team and then eventually the X-Men.
Because of his shapeshifting abilities that are similar to Mystique's (though he can break apart like dough), it makes sense that Morph has never made it to the movies, but that could change if Mister Sinister is introduced. Morph is a complex character who has been portrayed as both good and bad. At one point, he was a mentor to Wolverine, but he is later a slave to Sinister.
We know very little of Charles Xavier's life in between "First Class" and DoFP, which sets up the introduction of his estranged son, David Haller. Due to his traumatic upbringing, David has severe mental illness, with different powers being manifested by his various personas (hence, his name is Legion).
Legion is instrumental to the continuity presented in "Age of Apocalypse" when he travels back in time to kill Magneto, but kills Charles Xavier by accident, thus creating an alternate timeline. Though this storyline relates to Apocalypse, I honestly doubt we'll be seeing more alternate timelines being presented.
OK, technically Warlock is an alien mutant, not a human one, but that doesn't mean we don't want to see him on the big screen. His character could signal the Phalanx Covenant story arc when humans use his power to mutate themselves, thus giving them an edge over mutants. Plus, how cool would it be to have an alien join the X-Men?
This one's a no brainer, as Forge is a popular X-Men member who has the power of genius invention. I'm guessing they didn't include him in "First Class" because they wanted to save him for when Xavier would build the actual school, along with the various technology and equipment we see by the first X-Men film.
It's kind of hilarious that we got Sunspot before Sunfire (seriously, where was he in [The Wolverine](movie:34674)?), but the wait will probably pay off in "Apocalypse." Sunfire is a Japanese mutant who can convert solar radiation into plasma.
Though he joins the X-Men, I think a good story-line for the movie would be to present him as one of the possessed mutants used by Apocalypse, thus making him a villain at first.
#14 Marrow (and any of the other Morlocks)
Marrow is a mutant whose bones can grow out of her body, thus making her a mutant that can't blend in with humans. This prompts her to eventually join the Morlocks, who are mutants that live underground due to their physical appearances.
For "Apocalypse," Marrow and the rest of the Morlocks could be called upon to help in the fight against Apocalypse and his Four Horsemen, though it would be understandable to hold off on introducing them. Instead, we could simply meet Marrow as a student and witness her joining the Morlocks later on due to her appearance.
Seriously, if we're going to tackle the 1980s, then we're going to need Dazzler! She's a mutant who uses her ability to transduce sound into light to become a singer/entertainer. With mutants now "outed," we could be introduced to her as an outspoken mutant who shows off her powers in concerts.
If Fox is smart, they'll reintroduce a younger Nightcrawler as the child between Mystique and Azazel (before the events of DoFP, obviously). This means that we could also meet Nightcrawler's half-brother, Abyss.
Abyss is able to unravel his body into tendrils that allow him to suck people into a void in his chest. This void opens up to the Brimstone Dimension, the world that Nightcrawler passes through when he teleports. A possible (maybe future) storyline would be when Abyss and Nightcrawler team up to stop Azazel from invading Earth with his other-dimensional army.
That would mean, of course, that Azazel was only presumed dead in DoFP and could have escaped into the Brimstone Dimension. Can you say spin-off?!
#17 Omega Red
Lest we forget the Cold War is going on during the 1980s, which means...Omega Red. Created as the Soviet Union's version of the Weapon X program, Omega Red is a cyborg with the same healing factor as Wolverine.
One of his deadliest powers is that he secrets a pheromone that weakens anyone who comes near him, but he has to drain the life-force of Mutants continuously in order to stay alive.
Though Omega Red is a big bad that will most likely be served as Wolverine's next solo-outing foe, "Apocalypse" could easily set him up through a cameo or teaser to get fans excited.
Nightcrawler: Though he isn't a "new" mutant to the films, we still want to see a younger Kurt Wagner back in action.
Deadpool: Need I say more? Thanks to the time-traveling of DoFP, Fox now has the chance to correct their butchering of this character.
Gambit: We already know that Fox is bringing the Ragin' Cajun back as a "recasted" Channing Tatum, but can we expect to see him in "Apocalypse?" My money is on yes.
Sabretooth: One of the few things I liked about X-Men Origins: Wolverine was Liev Schreiber's memorable portrayal of Sabretooth. I doubt we've seen the last of him.