While it's almost two years until "X-Men: Apocalypse" is shown, the X-Men canon is just too rich with characters and dramatic storylines that would translate well on film. A psionic evil entity borne out of the uncomfortable fusion of Professor X and Magneto's collective consciousness, it could be a fitting exit for the Charles Xavier and Erik Lehnsherr.

Apocalypse is the most powerful mutant and the movie that will be made with him as the villain will be similar to an 'extinction level' disaster movie, the only worthy villain that would top that would be Onslaught.

What Culture had a feature on the next set of villains that should follow Apocalypse-a rather daunting task:

"Onslaught would be the ultimate villain for the X-Men movie franchise, as he was created by the merging of the consciousnesses of Professor Charles Xavier and Magneto.

This violent clashing of Magneto and Xavier's minds resulted in all of the anger, grief and vengeful feelings in Magneto's head entering Xavier's consciousness and merging with all the suppressed negative feelings Xavier had stored away for the previous thirty years of his life. The consequence of this was the manifestation of a powerful psionic evil being who would go on to be known as Onslaught. When a being created from the minds of Magneto and Charles Xavier is evil, you know you're in trouble.

Onslaught would make a superb 'final' villain to finish the X-Men franchise, as they don't come much better than him in terms of origins, power and significance. Seeing Magneto and Xavier having to team up against something they inadvertently created would be fantastic."

It is presumed that Fox would eventually have to end the saga of Professor X and Magneto. They have already rebooted it in "First Class" and they rehashed it even more in "Days of Future Past." What better way than to see them in a Pyrrhic victory style exit to stop the nemesis that they created.

The end of Professor X and Magneto would be the end of an era but by no means the end of the mutants. Fox could then rebuild with the new generation of mutants, perhaps spearheaded by "X-Force" and feature characters that are 'grounded' (Memo to Marvel Phase 3: once you go cosmic, you can't go back) but popular like Gambit and Deadpool.

These are all speculations on the future of the mutant franchise. Onslaught was quite a mess in the comics in terms of execution (directly affected by Marvel's real world crisis) but the character and the storyline has much potential. The movie version could live up to it.