Destiny is a major anti-hero we have yet to see come to the big screen! She's actually an incredibly old mutant with a pretty incredible tie many characters, but especially to Mystique! When she was a child Destiny recorded thirteen diaries of prophecies regarding future events, mostly in the 20th and 21st centuries. When she finished the diaries she realized she was blind, and the horrific images she'd seen haunted her so she enlisted Mystique's help to understand the recordings, and to stop several of the events from happening, however the two fell in love and become one of the highest profiled gay couples in all of Marvel history. Destiny was eventually killed by the villain Legion, who is Xavier's estranged son.
I think it would be incredible to see Destiny come to life on screen. I don't even care if we see her relationship with Mystique as romantic. I love the idea of having a mutant who can see the future and is trying to stop specific events from happening. What could it even more interesting is if we bounced between the present and the past with the older cast and the younger cast. As the young cast is interacting with Destiny, the older cast could be trying to decipher her journals after her death. Both teams could be attempting to stop separate incidents from occurring.
Nori was originally born in Japan but when her mutant powers manifested and she couldn't control the electricity her body was naturally creating she ran away from home. She became homeless and without any training her body would absorb nearby electricity until the buildup was dangerous for anyone within miles, but after an altercation with a bar tender a fellow mutant took her to the Xavier Institute where Beast designed armored gauntlets for her hands to help control her electricity, much like Cyclops' visor could control and contain his optic energy.
Surge eventually becomes the leader of the Young X-Men, and one of only 27 students who remained with their powers after M-Day (a dark era for the X-Men when 99% of the world's mutant population was de-powered making mutants an endangered species). The Young X-Men have fought alongside the regular X-Men during times of desperation, and the Young X-Men would make such an awesome movie! We could still have it set at the Xavier Institute, but with more of a High School feel to it as we focus on the students, with a possible cameo from Patrick Stewart or Famke Janssen.
Sam grew up in a large family whom he had to begin providing for after his father's sudden death in the local mine, which for irony's sake is where Sam started working. One day he was trapped in the mine just as his father was but he unconsciously unlocked his mutant ability and escaped. Cannonball is able to create a jet stream, and an impenetrable force around his body as he flies that allows him to blast through any object.
Xavier takes a liking to Sam and invites him to join his team the New Mutants as his first "new" team since the other X-Men had grown to adulthood. The New Mutants eventually leave Xavier for Cable's team X-Force and train under him as more of a Dark Ops team. It is revealed that Sam is an "External", which is explained by Cable as a mutant who is basically immortal, and he begins to train Cannonball with his original mission: Defeat Apocalypse (who's also an External,) who in Cable's future had conquered the world.
Sam later goes back to help out his family, where a few of his other siblings have become to manifest mutations too. Sam again gains from his leadership experience by aiding his brothers and sister, and eventually back to the X-Men as a full member of their team. Later he even becomes an Avenger hoping to help bridge the gap between mutants and humans.
With so much history and comic book connections it's surprising we haven't seen Cannonball in a film yet! I think our best bet to see him join the Universe would be in the New Mutants television show that Fox is probably developing, or in the X-Force movie that has also been highly rumored.
Victor grew up in a small town in Illinois where his reptilian features became prominent at a very early age, however the town accepted him and loved his family. However once anti-mutant propaganda started spreading through the country after a few incidents his parents got nervous and sent him to Xavier's for his safety. He might be one of the only few X-Men who had a positive upbringing and I think that would play very well into the "acceptance" theme that is at the heart of the X-Men stories.
Victor has reptilian skin and scales and can also climb walls, he has camouflage, and a prehensile tongue BUT his coolest ability is to be able to grow back his own limbs like a lizard losing it's tail to a predator.
Anole is also in a unique position as an out and proud homosexual mutant, and although this hasn't been developed in a romantic way in the comics his character has sought out after teacher Northstar to help guide him.
He become one of the Young X-Men after M-Day and watched several of his fellow students murdered at the hands of Stryker and other fanatics who used that time to attempt to assassinate the mutant population. Since M-Day he has finished school at Xavier's and become a member of the board of Worthington Industries under fellow X-Men Angel.
Megan was raised as a Welsh teenager, but later found out that villains Mastermind and Lady Mastermind are her half-siblings. Her powers include: rainbow wings that allow flight and create pixie dust which causes harmful hallucinations, strong teleportation she also has limited magical abilities (although they continue to develop).
After M-Day she was used to help teleport mutants to the Institute as a whole "safety in numbers" thing, and after Nightcrawler's death she was promoted to full X-Men status as the team needed someone to fill his teleporting shoes.
Pixie would be a hardcore member of any future X-Men movie, she's a young and hot, but badass, chick!
Hope's birth is still surrounded in mystery, but she was the first mutant born after M-Day and her birth caused a huge amount of problems for the X-Men as they were one of three factions hoping to find the baby along with the Purifiers led by Stryker and the Marauders lead by Mystique who found Hope because of Destiny's journals. In the end though Cable takes the baby with the X-Men's permission and goes into the far future to hide her from those wishing her harm. There he raises her as his own daughter and returns a few years later now with a teenage Hope.
Even though her powers of mimicry are more like Rogue's (just without the touch of death) and aren't anything like Jean's Hope is till considered an Omega Level Mutant and there have been plenty of teases of her being in control of the legendary Phoenix force.
I hope that after we see Hugh Jackman retire as Wolverine we'll get another mutant badass Cable to become a consistent character in the X-Men films, and some of his best character moments are him raising Hope, it really balances out the character's reckless and wild side.
At age ten Sammy began experiencing changes in his physical appearance, he started to look like a fish, and gained the ability to breathe underwater. With his classmates ridiculing him constantly he decided to take a gun to school, but before he carried out his plan Xavier visited him and recruited him to the Institute. At the Institute Squidboy and the newly reformed Juggernaut became unlikely friends, and after he left the Institute for a time Juggernaut rescued him from his abusive, drunk father and brought him back to Xavier's. The two bonded over their similar experiences with their own fathers.
Later Juggernaut was working with the X-Men as a double agent and infiltrated the New Brotherhood of Mutants led by Black Tom Cassidy. When they were in the woods outside Xavier's Sammy stumbled upon them and Cassidy killed Squidboy in front of his friend. Sammy died believing Juggernaut had betrayed his young friend and the X-Men and because of this Cain left the X-Men distraught.
Squidboy also appeared in the short lived cartoon series "Wolverine and the X-Men" on a boat heading for the mutant island Genosha where he befriended Nightcrawler and helped him rescue the mutants who were being abused by several crew members.
Sammy would make such a great addition to a movie! Even his death would be emotionally heartbreaking, what could be worse than seeing a ten year old we're already emotionally invested in be murdered senselessly by the bad guy?
Raised in Afghanistan Soorya is sold into slavery at a very young age, and permanently separated from her family, when her new owners attempt to remove her niqab (her cloth face covering) she instinctively fights back, and unknowingly turns into her dust form for the first time, creating a wind storm so great that it tears the skin off her aggressors, killing them. Soon after she is found by Wolverine who brings her to the Institute.
Another of the few students left after M-Day, Soorya joins Surge, Anole and others as the Young X-Men. They go after Stryker's Purifiers without permission from the teachers, the X-Men, and in the end get Jay Guthrie killed.
Dust would help with some much needed diversity among superhero movies, not just because she's a woman but because she's Islamic and always is seen wearing her traditional burqa, PLUS she's got a rich history and so many connections to other characters. We could even see her in the initial action sequence in Wolverine 3 with her rescuing her and taking her to America!
The Stepford Cuckoos have a pretty messed up backstory - even as far as comic book characters go! Originally they were believed to be quintuplets all born with exceptional telepathic abilities. They joined the Institute and spent a lot of time with teacher Emma Frost, and the five became rivals with student Quentin Quire, and even though it seemed all five Cuckoos were so psychically linked that they basically shared a mind, one of them stood out to Quire - Sophie - and he fell in love with her. Unfortunately for him she was the one who stopped him from destroying the school at the cost of her own life. This caused the other four "sisters" to despise Frost, believing she should have seen Quire's mind and prevented their sisters death.
Soon after another of the Cuckoos, Esme, decided to betray the X-Men for the teacher she believed to be Xorn, but was actually Magneto in disguise and his new Brotherhood of Mutants killed her and she died in Frost's arms.
A little later the Phoenix Force resumed it's search for a host, eventually settling on Emma and with the help of the three Cuckoos they expelled it from their teacher, but a fragment of it hosted itself inside the Cuckoos "leader" Celeste.
It is later revealed that the Cuckoos are actually not quintuplets but they were grown in a lab from ova harvested from then villain Emma Frost by the Hellfire Club. The remaining hundreds of clones remain hidden in an underground lab of which only a few X-Men, including Frost, know it's location.
Emma Frost is dead in our X-Men continuity, at least according to Magneto in DOFP. A fact I'm disappointed with as she plays such a huge part in the last two decades of X-Men comics. One such story includes a time where her diamond form is shattered and then kinetically re-attached by Jean Grey. I suppose we could still see this play out in the movies if someone somewhere has kept Emma's pieces and Magneto only thinks she's dead, or maybe the Cuckoos would be a really unique way to resurrect Frost as her clones.
Well there are plenty, PLENTY more X-Men that deserve to be depicted in upcoming films. We have so many opportunities coming up, it seems like the X-Men universe is largely expanding. We're getting three movies in 2016, Wolverine 3 coming in 2017, a rumored television show and several rumored/announced-but-not-announced movies. With so many rich characters the opportunities are endless and I get really excited!