Fans of the much-awaited fourth season of "Once Upon a Time" are in a buzz as the show's premiere is just rounding the corner.

ABC's hit fantasy-drama series is set to return onscreen this September. As the premiere date is fast-approaching, rumors have been continually making rounds online.

It has been famously reported that some characters from the popular Disney animation "Frozen" will be appearing in the fourth season. This was after the finale of season 3 showed a mysterious character that formed from a blue liquid, apparently reminiscent with that of Queen Elsa from "Frozen".

Although it was not clear whether the new characters will be playing as protagonists or villains, "Once Upon a Time" co-creator Adam Horowitz gave hints as to the characters' roles in the show. 

"We want to tell a story that is uniquely ours but also honors those characters [in the 2013 animated movie "Frozen"] that everyone fell in love with," said Horowitz to TVLine according to a report by International Business Times.

He continued, "The thing we love about Elsa is she is perceived to be a villain but is clearly misunderstood, and that goes to the heart of our show." This raised speculations that Elsa would possibly be playing as the villain in the show.

Meanwhile, TV Line reported that the casting for the "Frozen" characters were already done. Georgina Haig, Elizabeth Lail, and Scott Foster will be playing the roles of Elsa, Anna, and Kristoff, respectively.

The site also reported that ABC Entertainment president Paul Lee considers having "Frozen" characters on the show as a wonderful asset. He even revealed that Disney's chief creative officer John Lasseter has visited the show's set in Vancouver.

"Once Upon a Time" Season 4 is set to be back on television screens this September 28, 2014.