A prequel is a work that portrays events which are set in the same "universe" as a previously completed narrative, but at an earlier time. The word is a neologism, dating to the early 1970s; it is a portmanteau formed from pre-, meaning before, and sequel, a work which takes place after a previous one. "The term has recently slipped into common usage with its popularization by the advent of Star Wars Episode I: The Phantom Menace" wrote Chris Deever in Truth in Cinema, May 28, 2001. The Star Wars prequel trilogy greatly popularized the term in American culture.

Like sequels, prequels may or may not conern the same plot as the work from which they are derived. Often, they explain the background which led to the events in the original, but sometimes the connections are not as explicit. Prequels often play on the fact that the audience knows what will happen next, using deliberate references to create dramatic irony.

The idea of a prequel is not new. Richard Wagner's opera Das Rheingold in his Ring Cycle was composed as a prequel to his earlier Siegfried. The Silmarillion contains prequels for The Lord of the Rings.

Another example of a prequel in C. S. Lewis' The Chronicles of Narnia, is The Magician's Nephew, a prequel to The Lion, the Witch, and the Wardrobe which was written first.

See also: sequel, back story, interquel, retcon