Wall Of X-Men excluding Cyclops and Jean Grey / Marvel Girl, with the above "original" image tweeted by director Bryan Singer. Here's some close-ups posted below, in case you folks are not too keen to make with the clicks:
Jennifer Lawrence as "Raven / Mystique"
Nicholas Hoult as "Hank McCoy / Beast"
Hugh Jackman as "Logan / Wolverine"
Michael Fassbender as "Erik Lehnsherr / Magneto"
James McAvoy as "Charles Xavier"
Peter Dinklage as "Unknown"
Ellen Page as "Kitty Pryde / Shadowcat"
Halle Berry as "Ororo Munroe / Storm"
Shawn Ashmore as "Bobby Drake / Iceman"
Ian McKellen as "Erik Lehnsherr / (Older) Magneto"
Anna Paquin as "Marie / Rogue"
Patrick Stewart as "(Older) Professor Charles Xavier"
Fan Bing Bing as "Blink"
Omar Sy as "Unknown"
James Marsden as "Scott Summers / Cyclops" (rumored)
Lucas Till as "Alex Summers / Havok" (rumored)
(Cast list via IMDb)