
Adan Canto who played Paul Torres in
The Following was cast, according to his own Twitter, in
X-Men: Days of Future Past. His tweets are collected here:
link. There's also a picture of him with the cast, Ian McKellen and Patrick Stewart, among others. In one of his tweets he mentioned he "might turn into a ball of fire" if someone pissed him off. So, fans now speculate he might be playing Sunspot:

If he is, then I think it's a pretty accurate casting. Sunspot should've appeared in XMFC already but was written out. Now it looks like he's back in the game. I'm glad for Canto, he's a really good actor and deserves to become famous!
Also, funny thing: XM:DOFP also stars Shawn Ashmore who was with Adan Canto in
The Following this year! Ha :) And Kevin Bacon was in XMFC. Funny.