A new villain is coming to Storybrooke. According to E! News, Rebecca Mader has been cast to play a "major" villainous character but the identity is being kept under wraps. The source said Mader will appear in the second half of the show and could appear on "multiple episodes."

"We're told she will be a major character, with a major arc, and it's a meaty role," E! writes. "We can tell you that you will find out the twisted answer soon enough! Following the sure-to-be mesmerizing episode, Mader's fairytale identity will be revealed in an action-packed promo that will tease the long road of adventures our characters will face in the second half of the season."

During New York Comic Con, executive producer Adam Horowitz revealed that several new characters would be added to the season including Ursula, Rapunzel and Cruella de Vil. Since it was recently announced that "The Originals" star Alexandra Metz will play the long-haired Rapunzel, and Lana Parilla (who plays Regina Mills) will also play Ursula, fans are speculating that Mader is going to be the Dalmation-stealing Cruella.

Fans are also speculating that the "Lost" actress could be brought into the show as the "mother" of Rumpelstiltskin or the Wicked Witch of the West. Unfortunately, fans of the show will have to wait until Dec. 15 to get a glimpse of the new character during the winter finale and will be introduced to the new villain in March when Season 3 returns for their second half.

In other "Once Upon a Time" news, a source told TV Line that Metz's Rapunzel could be appearing for more than one episode but nothing is set in stone yet. Fans of "The Originals" may remember Metz as Katie, a witch who tried to kill Marcel but failed. She will make her debut appearance in the ABC fairytale show during episode 14.

"Once Upon a Time" airs Sundays at 8 p.m. on ABC. 

Which villain do you think Rebecca Mader will play?