Once Upon a Time season 4

The fourth season of the American ABC fantasy-drama series Once Upon a Time was announced on May 8, 2014. Like the previous season, it was also split into two volumes, with the first airing from September 28 to December 14, 2014, and the second from March 2 to May 10, 2015. Ginnifer Goodwin, Jennifer Morrison, Lana Parrilla, Josh Dallas, Emilie de Ravin, Colin O'Donoghue, Jared S. Gilmore, and Robert Carlyle return as principal cast members from the previous season, and are joined by Michael Socha, reprising his role from the spin-off series Once Upon a Time in Wonderland, in his only season as a regular.

Existing fictional characters introduced to the series during the season include the main antagonists for the two volumes, the Snow Queen and the Queens of Darkness (a triad of villains including returning character Maleficent, and new characters Cruella de Vil and Ursula), alongside Elsa, Anna, Kristoff, the Apprentice, Little Bo Peep and Poseidon.