Stephen Sondheim, one of Broadway history’s songwriting titans, whose music and lyrics reset the artistic standard for the American stage musical, died Nov. 26 at his home in Roxbury, CT. He was 91.

An intellectually rigorous artist who perpetually sought new creative paths, Mr. Sondheim was the theater’s most revered and influential composer-lyricist of the last half of the 20th century. His work melded words and music in a way that enhanced them both, The New York Times said. From his earliest successes in the late 1950s, when he wrote the lyrics for “West Side Story” and “Gypsy,” through the 1990s, when he wrote the music and lyrics for “Assassins” and “Passion,” he was a relentlessly innovative theatrical force.

The first Broadway show for which Mr. Sondheim wrote both the words and music, “A Funny Thing Happened on the Way to the Forum,” won a Tony Award for best musical and ran for more than two years. In the 1970s and ‘80s, his most productive period, he turned out a series of strikingly original and varied works, including “Company” (1970), “Follies” (1971), “A Little Night Music” (1973), Pacific Overtures” (1976), “Sweeney Todd” (1979), “Merrily We Roll Along” (1981), “Sunday in the Park With George” (1984), and “Into the Woods” (1987).

He wrote soliloquies, conversational duets and chatty trios and quartets. For “Night Music,” he wrote two sarabands, two mazurkas, a polonaise, an etude and a gigue. Overall he wrote both the music and the lyrics for a dozen Broadway shows, plus compendium revues like “Side by Side by Sondheim,” “Putting It Together,” and the autobiographical “Sondheim on Sondheim.” Five of them won Tony Awards for best musical, and six won for best original score.

In addition to his theater work, Mr. Sondheim wrote occasional music for films. Six cast albums from his shows won Grammy Awards, and “Send In the Clowns” won the Grammy for song of the year in 1975