Grease is a 1971 musical by Jim Jacobs and Warren Casey. The musical is named for the 1950s United States working-class youth subculture known as the greasers. The musical, set in 1959 at fictional Rydell High School (loosely based on William Howard Taft School), follows ten working-class teenagers as they navigate the complexities of love, cars, and drive-ins. The score attempts to recreate the sounds of early rock and roll. In its record-breaking original Broadway production, Grease was a raunchy, raw, aggressive, vulgar show. Subsequent productions sanitized it and tamed it down. The show tackles such social issues as teenage pregnancy and gang violence; its themes include love, friendship, teenage rebellion, sexual exploration during adolescence, and, to some extent, class consciousness/class conflict.

Grease was first performed in 1971 in the original Kingston Mines Theatre in Chicago, located in an old trolley barn (now the site of a hospital parking garage). From there, it has been successful on both stage and screen, but the content has changed drastically and its teenage characters have become less Chicago habitués and more generic. At the time that it closed in 1980, Grease's 3,388-performance run was the longest yet in Broadway history, although it was surpassed by A Chorus Line a few years later. It went on to become a West End hit, a hugely successful film, two popular Broadway revivals in 1994 and 2007, and a staple of regional theatre, summer stock, community theatre, and high school and middle school drama groups. It remains Broadway's fourteenth longest-running show.

Grease may refer to:

Musical is the adjective form of music. It may also refer to: