After Once Upon a Time‘s midseason finale Sunday night, ABC’s preview for the second half of the season revealed that the green-skinned villain (aka Elphaba — if the show uses the character’s Wicked name*) is coming aboard. She’s played by Rebecca Mader (Lost), who was previously announced to be joining the fantasy series in a top-secret role. The move intriguingly adds the merry old land of Oz to the show’s wealthy tapestry of literary and cinematic universes. Who else from Oz might show up next?