Warren Casey (April 20, 1935 – November 8, 1988) was an influential American theater composer, lyricist, writer, and actor, best known for co-creating the iconic musical "Grease" with Jim Jacobs. Born in Yonkers, New York, to Peter L. Casey, a steamfitter, and Signe (née Ginman) Casey, a nurse, he graduated from Gorton High School in 1952 and earned a Fine Arts Degree from Syracuse University in 1957.

Casey met Jim Jacobs in the mid-1960s while acting with the Chicago Stage Guild. Their collaboration led to the creation of "Grease," a musical that captures the essence of 1950s high school life and rock 'n' roll culture. The show premiered in 1971 at the Kingston Mines Theater in Chicago and later moved to New York City, where it became a Broadway hit, earning Casey a Tony Award nomination for Best Book of a Musical. "Grease" went on to become a global phenomenon, inspiring a successful film adaptation and numerous stage productions worldwide.

Beyond "Grease," Casey's acting credits include the original production of David Mamet's "Sexual Perversity in Chicago" in 1974. He was also involved in founding the Victory Gardens Theater in Chicago and contributed to various other theatrical works, including "Mudgett" and "Island of Lost Coeds."

Warren Casey passed away from AIDS-related complications in Chicago at the age of 53. At the time of his death, he was working on a new musical with Brazilian performer Valucha deCastro. His legacy endures through the enduring popularity of "Grease" and his contributions to American theater.