CATS is a musical composed by Andrew Lloyd Webber, based on Old Possum's Book of Practical Cats by T. S. Eliot, and produced by Cameron Mackintosh. The musical tells the story of a tribe of cats called the Jellicles and the night they make what is known as "the Jellicle choice" and decide which cat will ascend to the Heaviside Layer and come back to a new life. Cats also introduced the song standard "Memory".

Directed by Trevor Nunn and choreographed by Gillian Lynne, Cats first opened in the West End in 1981 and then with the same creative team on Broadway in 1982. It won numerous awards, including Best Musical at both the Laurence Olivier Awards and the Tony Awards. The London production ran for twenty-one years and the Broadway production ran for eighteen years, both setting new records. Actresses Elaine Paige and Betty Buckley became particularly associated with the musical. One actress, Marlene Danielle, performed in the Broadway production for its entire run (from 1982 until 2000).

As of 2014, Cats is the second longest-running show in Broadway history, and was the longest running Broadway show in history from 1997-2006, surpassed by The Phantom of the Opera. Cats is the fourth longest-running West End musical. It has been performed around the world many times and has been translated into more than 20 languages. In 1998, Cats was turned into a made-for-television film. mposed by Andrew Lloyd Webber, the production of Cats is based on T. S. Eliot's Old Possum's Book of Practical Cats (1939), which the composer recalled as having been a childhood favourite. The songs of the musical comprise Eliot's verse set to music by the composer, the principal exception being the most famous song from the musical, "Memory", for which the lyrics were written by Trevor Nunn after an Eliot poem entitled "Rhapsody on a Windy Night". Also, a brief song entitled "The Moments of Happiness" was taken from a passage in Eliot's Four Quartets. Andrew Lloyd Webber began composing the songs in late 1977 and premiered the compositions at the Sydmonton Festival in 1980. The concert was attended by T.S. Eliot's wife, Valerie Eliot and she loved the songs that Webber had composed. She gave her blessing for the songs to be adapted into a musical stage play. Rehearsals for the musical began in early 1981 at the New London Theatre. Due to the Eliot estate asserting that they write no script and only use the original poems as the text, the musical had no identified plot during the rehearsal process, causing many actors to be confused about what they were actually doing. An unusual musical in terms of its construction, the overture incorporates a fugue