At this point, I'm not even sure what Matthew Vaughn's "X-Men: First Class" (aka "X-Men 4: Sorry About X-Men 3") is supposed to be - everyone knows it's a "young Xavier & Magneto" story with mostly new characters and younger versions of the familiar ones, but no one yet seems willing to say whether this is a prequel like "Origins: Wolverine" (though casting new actors for Xavier and Cyclops when "O:W" had different ones would seem to negate that) or a reboot.
What everyone has been more-concretely wondering has been just what the "bad guy" is, since this is supposedly the pre-villain Magneto. The government? Other mutants? Mr. Sinister? Well, a dig through the various bits of casting-news turns up a fairly intriguing possibility.
Firstly, today we learn via io9/XMF that January Jones is apparently playing Emma Frost, aka "The White Queen," (another role someone else already had in "Origins") generally-speaking a role most fans begin and end caring about to the degree that she might wear "the costume." But then again, remember that blip awhile back that Kevin Bacon was playing "a bad guy" in this, too? Well, did anyone bother to go look and see if his "bad guy" had a name? Well, he does...
If you're an X-Men fan, that name alone ought to send something up your spine - especially coupled with the constant refrain of Frost being a "major" character in the film. In the comics, they were two parts of a bad-guy collective called "The Hellfire Club" - a bunch of Euro-flavored mutant aristocrats who's organization had more than a hint of S&M/instutionalized-decadence hovering about it (re: corsets, whips and lots of anachronistic Victorian fashion) and who's actions more or less kicked-off the infamous "Dark Phoenix" storyline (the Club and the story are both generously-"borrowed" references from an old "Avengers" storyline - the British spy show, not the comic.)
So is some version of THIS the "big threat" for "First Class?" On the one hand, it fits nicely into Vaughn's ever-expanding wheelhouse. On the other hand, an even remotely-faithful version would be pretty far outside "typical" for the series or Fox superhero movies in general: In their original incarnation, the Club seduces Jean Grey into joining their ranks by using illusions to let her live out her "darkest fantasies." Among those fantasies? Morphing into a female plantation mistress in the antebellum American South and taking fetishistic pleasure in personally whipping a disobedient slave girl - "played" in the fantasy by lone black X-Person Storm.