New details have been released about the mysterious Once Upon a Time villain role set to debut in the second half of season 3.

Enstars reported Thursday that Rebecca Mader (Lost) had been cast as an iconic fairy tale villain for Once Upon a Time. However, the identity of which villain she would be playing was a mystery.

However, a new report by E!Online suggests that the villain can only be one person: Cruella de Vil. The report states that Mader is playing a Disney villain with her own theme song, which Cruella de Vil famously has in the 101 Dalmatians movie from the 1960s.

She will be facing off against Regina (Lana Parrilla) in the second half of season 3 and serve as the major villain for the rest of the season. The identity of the villain will officially be revealed after the midseason finale on Sunday, Dec. 15.

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

In other Once Upon a Time spoiler news, executive producers Edward Kitsis and Adam Horowitz recently discussed the relationship between Mr. Gold/Rumple (Robert Carlyle) and Belle (Emilie de Ravin), assuring fans that they will be together for the second half of season 3.

"In the second half of the season, they are going to be in the same world for an extended period of time," Horowitz said. However, Kitsis added, "If you're a fan of Rumbelle, the second half of the season will further explore their relationship - in whatever state that is."

Once Upon a Time Spoilers: Will Henry & Peter Pan Switching Bodies Be Revealed? 

Once Upon a Time season 3 airs Sundays at 8 p.m. 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