Superherohype says it has confirmed that Nicholas Hoult (pictured, CLASH OF THE TITANS) has been cast as Hank McCoy (the Beast) and Caleb Landry Jones (THE LAST EXORCISM) will play Sean Cassidy (Banshee) in X-MEN: FIRST CLASS.
Entertainment Weekly says that Lucas Till (THE SPY NEXT DOOR) has also been cast in the film, possibly as Alexander Summers, brother of Scott Summers (Cyclops). 
In the comics, Alex would resent his brother’s leadership and by the book attitude, eventually rebelling as the pisionic-powered Havok.
The article warns this might be disinformation from 20th Century Fox, in an attempt not to reveal all the roles too early.
At first glance, Nicholas Hoult looks a little slight to play Hank McCoy, depicted in the early comics as a brainy, brawny, broad-faced and usually barefoot and cheerful character. (A nice change from the generally angst-filled teens at Professor Xaviers School for Gifted Students.)
It remains to been seen what path the Matthew Vaugn-directed film version will follow, and if McCoy will assume his later hirsute beastly form