and boy, is everyone included!
X-Men: Wolverine (duh), Kitty Pryde, Emma Frost, Cyclops, the Beast, Angel, Iceman, Rogue, Nightcrawler, Thunderbird/Forge (?goateed guy), Cannonball (?)
Villains: Polaris, Mystique, Blob, Magneto, Avalanche, Spiral, Mojo, Scarlet Witch, Quicksilver, Juggernaut, Shadow King, the Hulk (?!?), Vertigo, Senator Kelly, the Sentinels
Satellite Characters: Dust, Maverick, Gambit, Domino, Wolfsbahne, Xavier (dead?), Jean (dead?), Storm, Pyro, Multiple Man
I'm not much crazy for the animation style, but it's good news that they're focusing on a specific storyline and picking up from an established storypoint instead of rebooting the franchise.