James McAvoy, Michael Fassbender, Ian McKellen and Patrick Stewart to Star in New 'X-Men'

Bryan Singer is uniting the X-Men.

Singer is combining James McAvoy, Michael Fassbender, Jennifer Lawrence and Nicholas Hoult with Ian McKellan and Patrick Stewart in X-Men: Days of Future Past, the sequel to X:Men: First Class.

Stewart and McKellen portrayed X-Men founder Prof. Charles Xavier and renegade mutant leader Magneto in the original X-Men movies, the first two of which Singer directed and produced. 

McAvoy and Fassbender played Xavier and Magneto in First Class, the 2011 reboot of the franchise which was set in the early 1960s. 

Days of Future Past is a classic storyline that unfolded in two-issues of Uncanny X-Men in 1981, from writer Chris Claremont and artists John Byrne and Terry Austin. The story was partially set in an alternate future where surviving mutants have been penned in concentration camps, giant robots named Sentinels patrol America, and most of the X-Men have been hunted and killed. In the present day, the X-Men were forced to stop a key event from unfolding in order to keep that future from occurring.

With First Class using different X-Men than the 1980s comics, fan speculation how the storylines will translate and combine is sure to run wild.

Also up as a question is whether Hugh Jackman, who starred as Wolverine in the first trilogy and made a cameo in First Class, will come back for Days of Future Past. 

Tweets below:

I'd like to officially welcome back James McAvoy, Jennifer Lawrence, Michael Fassbender, & Nicholas Hoult to #XMEN for #DaysOfFuturePast

— Bryan Singer (@BryanSinger) November 27, 2012

Thrilled to announce @ianmckellen118 & @sirpatstew are joining the cast of #XMEN #DaysOfFuturePast #magneto #professorX More to come...

— Bryan Singer (@BryanSinger) November 27, 2012