Lost is an American science fiction adventure drama television series created by Jeffrey Lieber, J. J. Abrams, and Damon Lindelof that aired on ABC from September 22, 2004, to May 23, 2010, over six seasons and 121 episodes. It contains elements of supernatural fiction, and follows the survivors of a commercial jet airliner flying between Sydney and Los Angeles, after the plane crashes on a mysterious island somewhere in the South Pacific Ocean. Episodes typically feature a primary storyline set on the island, augmented by flashback or flashforward sequences which provide additional insight into the involved characters.

Lindelof and Carlton Cuse served as showrunners and are executive producers along with Abrams and Bryan Burk. Inspired by the 2000 Tom Hanks film Cast Away, the show is told in a heavily serialized manner. Due to its large ensemble cast and the cost of filming primarily on location in Oahu, Hawaii, the series was one of the most expensive on television, with the pilot alone costing over $14 million. The fictional universe and mythology of Lost were expanded upon by a number of related media—most importantly a series of mini-episodes called Missing Pieces; and a 12-minute epilogue, "The New Man in Charge".

Lost has regularly been ranked by critics as one of the greatest television series of all time. The first season had an estimated average of 16 million viewers per episode on ABC. During its sixth and final season, the show averaged over 11 million U.S. viewers per episode. Lost was the recipient of hundreds of industry award nominations throughout its run and won numerous of these awards, including the Primetime Emmy Award for Outstanding Drama Series in 2005, Best American Import at the British Academy Television Awards in 2005, the Golden Globe Award for Best Television Series – Drama in 2006, and the Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series.