Once Upon a Time in Wonderland is an American fantasy-drama series that aired on ABC from October 10, 2013, to April 3, 2014. It was created by Edward Kitsis, Adam Horowitz, Zack Estrin, and Jane Espenson for ABC Studios. The program is a spin-off of the ABC series Once Upon a Time and aired on ABC at 8:00 pm Eastern/7:00 pm Central on Thursday nights in the 2013–14 television season beginning October 10, 2013.

The series is based on the Lewis Carroll novels Alice's Adventures in Wonderland (1865) and Through the Looking-Glass (1871) but with a different twist from the other adaptations, and takes place in the same universe as Once Upon a Time in present-day Wonderland, with flashbacks to Wonderland before it fell prey to a dark curse. It follows the same setting as the parent series, including the use of Disney and Lost allusions. In addition, the series features occasional crossover events with Once Upon a Time that involve connections with the characters that are trapped in Storybrooke, Maine.

The series received mixed to positive reviews from critics, who praised its cast, visuals, and narrative, but criticized the muddled plot. On March 27, 2014, it was revealed that the series would be ending after one season, with the series finale airing on April 3, 2014. Actor Michael Socha, in his Wonderland role as Will Scarlet / Knave of Hearts, joined Once Upon a Time as a series regular for its fourth season.