It has been hinted many times that Elizabeth Mitchell will join the cast of "Once Upon A Time"  for season four. However, her role is still unknown. This makes the fans curious.

Show runner Adam Horowitz is excited about the "Lost" star appearing in the series. "She's awesome, we love her, we're so happy to have her and we can't wait for the audience to discover who she is playing," he told TV Line.

Rumors claim that Elizabeth Mitchell will play the role of a villain as there is no antagonist in the series. Elsa is reported to be a villain in the small screen adaptation of "Frozen". However, it is not confirmed whether or not her character will be sinister.

Meanwhile, the fourth season of Once will feature the story of the movie "Frozen". Once spoilers claim that Queen Elsa will be back in her original state as a villain in the story of the "Snow Queen". The TV series is known for twisting the original version of our beloved childhood fairy tales and turning the main characters into villains. However, show runners have confirmed that the TV version will follow the Disney movie.

The first episode is titled "A Tale of Two Sisters". The first episode will most likely feature the two sisters – Elsa and Anna. It could happen that the episode will show a back story of the sisters just like in the opening of the movie "Frozen". There were speculations that the first episode will expand on the reason the sisters end up in Storybrooke and what the other characters plan to do.

The fourth season will air September 28 featuring beloved characters from "Frozen". The show's creators and executive producers Edward Kitsis and Adam Horowitz confirmed that Elsa, Anna and Kristoff will definitely appear in show next season.