By Natalie Abrams
Updated September 05, 2014 at 10:37 PM EDT
David Livingston/Getty Images

Her face may no longer be green, but Rebecca Mader is sticking to her villainous side. The Lost alum has landed a guest-starring role on Blue Bloods, EW has learned exclusively.

Mader will play Tori, a sexy and brilliant attorney who is Erin’s old law school classmate—and her most bitter rival. Now the highly paid partner in a top law firm, Tori specializes in getting notorious criminals off for the crimes they have committed, and she mocks Erin’s “sanctimonious” disapproval.

Mader, who will appear in an episode slated for November, most recently starred as the green-with-envy Wicked Witch on Once Upon a Time. Her other TV credits include Fringe, White Collar and No Ordinary Family.

Blue Bloods returns Sept. 26 at 10 p.m. on CBS.