1. Cable
Nathan Christopher Charles Dayspring Summers is the time-traveling soldier known as Cable, who also happens to be the son of Cyclops and Madelyne Pryor. Pryor was a clone of Jean Grey, created by Mr. Sinister as he attempted to unite the Grey and Summers bloodlines to create a powerful mutant. Nathan as a baby was used as a pawn by Sinister and the evil Madelyne Pryor in the Inferno event, and was then lost to the future during the Fall of the Mutants storyline. Cable would then first appear in New Mutants #98, a time-traveler with a mission who would later be revealed as Nathan Summers. Cable would create and lead X-Force, join the X-Men, and play a crucial role in a number of X-events, especially those that involved Apocalypse. Cable was actually created by Mr. Sinister so he would have a powerful weapon against Apocalypse. Nathan was so powerful that his birth woke Apocalypse from his hibernation. He attacked X-Factor and infected Nathan with a techno-organic virus that started to ravage his body. Nathan was taken away to the future by a member of the futuristic Clan Askani, where the technology existed to save his life. Nathan, known as Dayspring and eventually Cable, was raised as a soldier and continued to fight against Apocalypse 2000 years in the future, until he returned to the X-Men's present to fight Apocalypse there. His incredible powers of telepathy and telekinesis are constantly hindered by the mental control it takes to restrain the T/O virus that continues to try and overake his body.
Cable's inclusion in X-Men: Apocalypse seems like it should be a guarantee, but there are a few clear hurdles to overcome. With such a rich backstory, only key elements of Cable's history may make it into the film, but all that matters is the militaristic mutant takes a stand against his greatest enemy alongside the X-Men. With time travel clearly playing a large part in X-Men: Days of Future Past, the groundwork is already being laid out to make Cable a reality for X-Men: Apocalypse. His appearance could easily lead into an X-Force movie featuring a number of the new mutants we hope to be introduced in X-Men: Apocalypse, further extending the X-Men's movie universe.
Like this list? Any other mutants you want to see in X-Men: Apocalypse? Let us know in the comments section!