Mitch Leigh, the theatre composer and jingle writer who had a single, but enduring, hit musical in Man of La Mancha, and who, with a handful of repeated, but dramatically escalating musical phrases, gave the world an aspirational anthem in "The Impossible Dream," died March 16, 2014. He was 86.

Man of La Mancha, a scrappy, straightforward musical telling of Cervantes' "Don Quixote," was based on playwright Dale Wasserman's teleplay "I, Don Quixote." The musical, which featured lyrics by Joe Darion, played five Broadway engagements. The first, in 1965 — which won the Tony Award for Best Musical, and made a star out of Richard Kiley as Don Quixote — ran 2,328 performances; revivals were seen in 1972, 1977, 1992 and 2002. The musical is also a staple at regional theatres around the country. Mr. Leigh also won a separate Tony for his score.

Aside from providing incidental music to a couple comedies in the 1960s, Man of La Mancha was Mr. Leigh's Broadway musical debut. The show would dominate his career. He would never have another hit remotely as big. Cry For Us All, based on the play Hogan's Goat, which he also produced, ran for nine performances in 1970. Home Sweet Homer, in 1976, ran for one. Saravá in 1979, written in collaboration with N. Richard Nash, fared better, playing for a half a year. Chu Chem, set in China in the 1400s, lasted for a couple months in 1989.

His last original Broadway show, Ain't Broadway Grand, based on the career of producer Mike Todd, played for less than a month in 1993. Despite his success with Darion on Man of La Mancha, Mr. Leigh never worked with him again. He used a different lyricist for each of his eight musicals.

He had better luck as a director, netted a Tony nomination for his staging of a 1985 revival of The King and I with Yul Brynner.

Mitch Leigh was born Irwin Michnick in Brooklyn on Jan. 30, 1928. He attended Yale, receiving a B.A. in Music in 1951 and a Masters the following year. He began his career as a jazz musician and writing radio and television commercials. His first commercial was for Revlon. In 1957, he founded Music Makers, Inc., a radio and TV commercial music publishing house. It became a multi-million-dollar business. Following the success of La Mancha, Mr. Leigh only wrote music for "high-budget commercials," according to a 1966 article in the New York Times.

In addition to "The Impossible Dream," Mr. Leigh composed one other tune known to millions: the "Nobody Doesn't Like Sara Lee" jingle.

Survivors include his wife of 42 years, Abby Kimmelman; their children, Rebecca and David; and a son from his first marriage, Andy.