Rebecca Romijn has joined the cast of ABC's huge hit, Ugly Betty.

She'll play the mystery woman who's been conspiring with Vanessa Williams' Wilhelmina character to take over the publishing company at the heart of the show, according to Variety. Her character has already been seen on the show, but in profile and covered in the dark; a different actress has been supplying the voice of the mystery woman.

Romijn is expected to begin work on Ugly Betty on Monday; her first episode should air in time for the February sweeps.