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.

Once Upon a Time is an American fantasy adventure drama television series that aired for seven seasons on ABC from October 23, 2011, to May 18, 2018. The action alternates between two main settings: a fantastical world where fairy tales happen, and a fictional seaside town in Maine called Storybrooke. The "real-world" part of the story unfolds with the characters of Emma Swan and her 10-year-old son, Henry Mills. Henry discovers the other people of the town are fairy-tale characters. The audience is shown the backstory of the town's people as fairy-tale characters, in conjunction with their unfolding stories in the "real-world". In the seventh and final season, the "real-world" portion of the story takes place in Seattle, Washington, in the fictitious neighborhood of "Hyperion Heights", with a new main narrative led by adult Henry, and his wife and daughter.