Hank McCoy is the Beast. Probably the most prominent character from the books to appear in the film – after Prof X and Magneto) and present in X-Men: Last Stand (played by Kelsey Grammar (Frasier) and introduced as an old friend of Professor X). He presents difficulties in that his CGI / Make up is intensive stuff but is a welcome addition to what is a unnecesarily attractive cast for mutated misfits. However will always be the most difficult character of the X-Men to bring fully to life on the big screen. This trailer suggests that Matthew Vaughn might’ve puled it off but without a full reveal who can say.
Emma Frost is / was one of the most challenging characters in the X-Men canon (unprecedented student death toll under her tutelage, unofficial psychic sex therapist to the team, former enemy and the only girl who could take Scott Summers way from Jean Grey – before she died – again) but looks like she’s been reduced to that of a bit player in this trailer. Emma Frost is in alliance with Shinobi Shaw as White Queen to his Black King of the Hellfire Club in the books. Simplified here, Frost looks like she’s a minion. Though to waste a character like Frost seems unlikely – particularly given her introduction in Origins: Wolverine.
This still leaves the familiar Professor X, Magneto, Shinobi Shaw, Angel and (below) Azazel. Plenty more to take a look at then if you haven’t managed to see the film yet.
Banshee: Sean Cassidy in X-Men (introduced as part of the second gen X-Men in Giant Size X-Men 1 along with Wolverine, Colossus, Nightcrawler, Warpath and Storm). Banshee lived on in the comic books for some time, a stable, reliable side character and came into his own as leader of Generation X (alongside Emma Frost) in which he, Frost and Sabretooth kept the next generation of kids out of the way of the Phalanx. In X-Men: New Class he’s almost the only character placed pretty much in line with continuity in the books as his age in the sixties reflects the age he’d be now (relative to Prof X). A mainstay of the books for some time Banshee was killed trying to stop a plane crash.
Havok has occupied most of the theories surrounding the decision to start at the beginning. Havok’s most notable feature in X-Men is that he is brother to Scott Summers (Cyclops) and has always lived slightly in the shadow of his brother. That clearly isn’t the case here as Cyclops is part of the modern day canon of the previous movies. At the X-Men: First Class panel at MCM it was a question aimed squarely at the writers. All they could say was that Havok is related in someway to Scott. Hard to figure out where they’re going with this but if a franchise is built hopefully all will be revealed.
The inclusion of Mystique is an interesting choice. Most viewers of previous X-Movies’d be aware that Mystique has a very clear resolution to her plot line. Her association with Erik Lensherr in this adds a neat reference point to both sets of movies (with the Wolverine Origins franchise sandwiched in the middle).