Now that the gang is back in Storybrooke and Peter Pan will, presumably, be defeated once and for all soon, Once Upon a Time needs a new Big Bad for the spring half of Season 3 (because let's be real: neither Regina nor Rumple even comes close to being a main villain anymore). And guess what — the town's newest baddie has already been cast!

The new villain will be be played by the show's nth Lost alum, Rebecca Mader, and we hear it's a meaty role. The problem? The exact identity of Rebecca's baddie is being kept under lock and key. We'll find out the truth for sure in the promo for the second half of the season, which will air after Sunday's midseason finale. Until then, we have to stick to speculating. Good thing that's our favorite pastime!

Here are three guesses for who the baddie will be.

The Wicked Witch. The show has been teasing the existence of an Oz universe for awhile now, so maybe that will finally pay off in the second half of the season. While showrunner Eddy Kitsis has said the second half of the season will mostly focus on Storybrooke and the Enchanted forest, that doesn't mean the Wicked Witch (of the East or West) couldn't find her way into one or both of those realms.  

Cruella De Vil. Fans have been chomping at the bits to see this iconic Disney baddie in action, and while, at 36, Rebecca is younger than Cruella is normally portrayed, we can see her pulling off a younger version of the fashion-obsessed villainess. And people have been wondering if the existence of the adorable Pongo is a hint that we'd one day run into Cruella...

Rapunzel's evil captor. Of course, the E! spoiler says that Rebecca is going to be playing an iconic fairy tale villain, and 101 Dalmatians and The Wizard of Oz aren't strictly fairy tales. Since the show has cast a Rapunzel, perhaps Rebecca will play the witch who locks  Rapunzel away. Sure, that's not the most famous of fairy tale villains, but that could be a good thing — it would give the writers lots of room to create a unique character.

Who do you think Rebecca will play? Sound off in the comments below!

Rebecca Martin is an Associate Editor at Wetpaint Entertainment and our resident Game of Thrones, Breaking Bad, and genre TV expert. Follow her on Twitter and Google+!

Credit: Celebified Photo: Once Upon a Time Casts Lost Alum Rebecca Mader as a New Season 3 Villain!