Emma Frost.
Emma Frost is fictional character from Marvel comics. She is a psychic type mutant with the ability to harden into her crystal form. The only downside is that while in her crystalized form, she is unable to utilize her psionic abilities. She was known to be a member of the X-Men and The Hellfire Club.
She was suppose to be a mentor of the Fearless slayers, but She was somehow caught by HYDRA and was replaced by Mystique.
In Fearles Slayer Movie: Viral Grid, after Mystique and Chameleon arrested, she took her position as mentor once again.