Raven Darkholme aka Mystique is a shapeshifting mutant who can mimic the the exact voice and appearance of anyone. Her natural appearance is her scaly blue skin, blood-red hair, and yellow eyes.

Raven Darkholme, for the upcoming X-Men: From The Ashes relaunch. As Declan says these are "thinly veiled codewords". Here is what he has said about that project in his newsletter since last year.