Lucas Till Returning as Havok in 'X-men: Days of Future Past'; Peter Dinklage's Role Revealed

Even as the cast of Bryan Singer's X-men: Days of Future Past has grown significantly, the only confirmed cast returning from X-men: First Class has been Michael Fassbender, James McAvoy, Jennifer Lawrence, and Nicholas Hoult. But today we've learned that at least one other is coming back, as Singer tweeted an image of Lucas Till, reprising his role as Alex "Havok" Summers.

The image seems to be of Havok in some sort of mutant army, and comes with the caption from Singer: "Mankind must put an end to war before war puts an end to mankind."  Havok's return poses some intriguing possibilities for the time-hopping film, as his brother Scott "Cyclops" Summers (James Marsden) will be in the story as well. And with the recent reveal that the militaristic X-force squad is soon to receive their own film, a mutant army could be the first step towards it.

Also, a couple of mystery roles have been revealed, but only one will come as a surprise. Vulture confirms that Peter Dinklage will be playing Bolivar Trask, the creator of the mutant-hunting sentinels that dominate the broken future the X-men are trying to prevent. We and others have had this one pegged for awhile, and Singer will likely confirm the news at Comic-Con. And Josh Helman, who joined the film in a "significant mystery role" a few weeks ago, is said to be playing a young William Stryker, the anti-mutant activist played by Brian Cox in X-2: X-men United.

X-men: Days of Future Past stars Ian McKellen, Hugh Jackman, Patrick Stewart, James McAvoy, Michael Fassbender, Jennifer Lawrence, Nicholas Hoult, Anna Paquin, Ellen Page, Shawn Ashmore, Peter Dinklage, Omar Sy, Halle Berry, Daniel Cudmore, Fan Bingbing, Evan Peters, Josh Helman, Boo Boo Stewart, and opens on May 23rd 2014.