Rebecca Mader will be playing the iconic Wicked Witch of the West when season 3 of Once Upon a Time returns in March.

The identity of who Mader would be playing was kept secret until Sunday night's midseason finale of Once Upon a Time. The trailer for the midseason premiere featured the reveal of Mader as the villainous Wicked Witch.

The Wicked Witch of the West, who is also known as Elphaba from the Broadway production Wicked, will be the primary villain for the remainder of season 3.

Robbie Kay, who plays Peter Pan on the ABC series, said that he was excited for Mader to appear as the Wicked Witch.

"It's certainly an exciting prospect for the show, so it will be interesting to see how they put a twist on [her character]," Kay told E! News recently. "To be honest, it would be fantastic for them to sort of delve into that whole Wizard of Oz land and to see whether they can implement more characters into the story."

Mader seems excited to be playing the iconic role as well, tweeting immediately after the episode ended. The actress tweeted, "The witches cat is FINALLY out of the bag!!!!!"

Mader also tweeted "#Wickediscoming," a nod to both her character and the Broadway show. She will likely be appearing in the midseason premiere and will be featured until the end of season 3.

Once Upon a Time Spoilers: 'The Originals' Actress Cast as Rapunzel 

Once Upon a Time season 3 returns on Sunday, March 9 on ABC.

Watch a trailer for the next episode of Once Upon a Time here:

Tags: Once Upon A Time Once Upon A Time Season 3 Spoilers