The ABC fantasy drama will introduce a version of The Little Mermaid’s Ariel, as well as both the title character and the villainous Jafar from Aladdin, according to TV Guide.
Horowitz and Kitsis also confirmed that they are eager to cast Lost actor Jorge Garcia on the show.
Garcia previously starred in Fox sci-fi drama Alcatraz, but the series was axed following a single season in May.
Once Upon a Time will return this fall on Sundays at 8/7c on ABC. In the UK, the series airs on Channel 5.