'Once Upon a Time': Rebecca Mader says 'you'll find out why I'm wicked'

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Rebecca Mader will take center stage on this week’s Once Upon a Time when the show finally takes a deep-dive into Zelena’s backstory in an episode aptly titled “It’s Not Easy Being Green.” EW spoke with OUAT’s resident wicked witch to talk about how Mader found out she’d scored the coveted role as one of this season’s baddies, what fans can expect from this Sunday’s episode, and more:

Mader remembers the day her agent called her and told her Once Upon a Time creators Eddy Kitsis and Adam Horowitz wanted her to be on the show. Despite her agent staying tight-lipped on the role Kitsis and Horowitz wanted her for, Mader says she had a feeling she’d be playing for the evil side.

“I knew I was going to be a villain — I just knew it!” says the English actress. “I feel like I should have been a bit more offended, but I was just excited to be a part of the show.”

That being said, Mader says she never would have imagined she’d be stepping into the shoes of one of the most iconic literary villains to ever grace the pages of a children’s book.

“I was thrilled when they finally told me I was going to be the wicked witch — I loved that film, but I was probably way too young the first time I watched it as a child,” recalls Mader. “I found the wicked witch so upsetting! I used to have nightmares about her coming to my house on her bike and kidnapping me in the middle of the night. Now I’m the one giving children nightmares, so it’s kind of come full-circle!”

But despite the notorious nature of her character, there’s still a lot of mystery that surrounds the wicked witch who plagues the citizens of Storybrooke. And if you’re one of the many Once-ers who’ve been itching for more info about Zelena, you’ll be getting a lot more insight into her character this Sunday.

“Things are building in terms of why I’ve come,” Mader says cryptically of her character’s motives. “But viewers will definitely find out more about Zelena this Sunday. You’ll find out why I’m green and why I’m wicked.”

As for whether Zelena’s origin story will pull from other infamous incarnations of the Wicked Witch — like that of MGM’s big-screen adaption starring Judy Garland, or Broadway’s hit musical Wicked — or if the showrunners will opt to create a brand-new backstory, the actress says she thinks it will be a mixture of both.

“They want to be original with it,” Mader said. “You’ll definitely see. Eddy and Adam will do what they do best and put their own spin on the classic.”

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