Who she is: Emma Frost
Her power: Emma Frost is a telepath, meaning she can read and control minds, project her voice directly into the minds of others, and create psychic illusions. She can also turn her entire body into diamond, which gives her superstrength and physical resilience while also protecting her from any psychic attacks.
Her story: Emma Frost has a power set that makes her valuable for both espionage and action, but she’s mostly eye candy in X-Men: First Class, introduced wearing lingerie and literally turning herself into a sparkling diamond woman. She’s something pretty to look at, and the movie doesn’t spend any time delving into why she’s part of Sebastian Shaw’s Hellfire Club. She helps Shaw deal with both U.S. and Russian military officials, and Charles Xavier and Erik Lehnsherr capture Frost in the midst of her psychic seduction of a Russian general. Magneto breaks Frost out of her CIA prison after he defeats Shaw at the end of the film, but X-Men: Days Of Future Past reveals that she dies in the decade that follows. (In X-Men Origins: Wolverine, Kayla Silverfox’s sister, Emma, has a similar ability to turn her body to diamond, but she is not Emma Frost.)
Played by: January Jones
Currently, Emma Frost is: Presumably dead, though we didn’t see a body and she can turn her body to diamond, so maybe she’s somehow survived.
Where will we see her next? Most likely nowhere given the unfavorable response to her character in First Class.