Once Upon a Time season 5

The fifth season of the American ABC fantasy-drama series Once Upon a Time was ordered on May 7, 2015. Like the previous two seasons, it was also split into two volumes, with the first airing from September 27 to December 6, 2015, and the second from March 6 to May 15, 2016. The season also saw the series reach its 100th episode, which aired on March 6, 2016 as the mid-season premiere. 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 Rebecca Mader and Sean Maguire. This season is the only one to feature Maguire in a regular capacity.

Existing fictional characters introduced to the series during the season include the main antagonists for the two volumes, King Arthur, Nimue and Hades, alongside Guinevere, Merlin, Merida, Percival, Hercules, Megara, Zeus, Poole, Jekyll and Hyde. The season also saw the return of numerous deceased characters from previous seasons, including the Blind Witch, Cora Mills / the Queen of Hearts, Peter Pan, Cruella de Vil, Baelfire / Neal Cassidy, Milah, Prince Henry, Liam Jones, Prince James, Gaston, Claude, and Stealthy.