NEW YORK >> Harold Prince, a Broadway director and producer who pushed the boundaries of musical theater with such groundbreaking shows as “The Phantom of the Opera,” ”Cabaret,” ”Company” and “Sweeney Todd” and won a staggering 21 Tony Awards, has died. Prince was 91.

Prince’s publicist Rick Miramontez said Prince died today after a brief illness in Reykjavik, Iceland.

Prince was known for his fluid, cinematic director’s touch and was unpredictable and uncompromising in his choice of stage material. He often picked challenging, offbeat subjects to musicalize, such as a murderous, knife-wielding barber who baked his victims in pies or the 19th-century opening of Japan to the West.

Along the way, he helped create some of Broadway’s most enduring musical hits, first as a producer of such shows as “The Pajama Game,” ”Damn Yankees,” ”West Side Story,” ”A Funny Thing Happened on the Way to the Forum” and “Fiddler on the Roof.” He later became a director, overseeing such landmark musicals as “Cabaret,” ”Company,” ”Follies,” ”Sweeney Todd,” ”Evita” and “The Phantom of the Opera.”

Sir Andrew Lloyd Webber, reached by phone today, told The Associated Press that it was impossible to overestimate the importance of Prince to Broadway. “All of modern musical theater owes practically everything to him.”

In addition to Lloyd Webber, Prince, known by friends as Hal, worked with some of the best-known composers and lyricists, including Leonard Bernstein, Jerry Bock and Sheldon Harnick, John Kander and Fred Ebb, and, most notably, Stephen Sondheim.

“I don’t do a lot of analyzing of why I do something,” Prince once told the AP. “It’s all instinct.”

During his more than 50-year career, Prince received a record 21 Tony Awards, including two special Tonys. He also was a recipient of a Kennedy Center Honor.

He earned a reputation as a detail-heavy director. Barbara Cook in her memoir “Then & Now” wrote: “I admire him greatly, but he also did not always make things easy, for one basic reason: he wants to direct every detail of your performance down to the way you crook your pinky finger.”

It was with Sondheim, who was the lyricist for “West Side Story,” that Prince developed his most enduring creative relationship. He produced “A Funny Thing Happened on the Way to the Forum” (1962), the first Broadway show for which Sondheim wrote both music and lyrics.

They cemented their partnership in 1970 with “Company.” Prince produced and directed this innovative, revue-like musical that followed the travails of Bobby, a perpetual New York bachelor ever searching for the right woman.

“Company” was followed in quick succession by “Follies” (1971), which Prince co-directed with Michael Bennett; “A Little Night Music” (1973); “Pacific Overtures” (1976); and “Sweeney Todd” (1979).

Their work together stopped in 1981 after the short-lived “Merrily We Roll Along,” which lasted only 16 performances. It wasn’t to resume until 2003 when Prince and Sondheim collaborated on “Bounce,” a musical about the adventure-seeking Mizner brothers that had a troubled birth and finally made it to Broadway as “Road Show.”

Born in New York on Jan. 30, 1928, Prince was the son of affluent parents, for whom Saturday matinees in the theater with their children were a regular occurrence. A production of “Julius Caesar” starring Orson Welles when he was 8 taught him there was something special about theater.

“I’ve had theater ambitions all of my life,” he said in his memoir. “I cannot go back so far that I don’t remember where I wanted to work.”

Some of his first stabs at producing included “The Pajama Game,” starring John Raitt and Janis Paige, and another musical smash, “Damn Yankees,” featuring Gwen Verdon as the seductive Lola.

In 1957, Prince did “West Side Story,” a modern-day version of “Romeo and Juliet” told against the backdrop of New York gang warfare. Directed and choreographed by Jerome Robbins and with a score by Bernstein and Sondheim, it, too, was acclaimed.

Yet even its success was dwarfed by “Fiddler on the Roof” (1964), which Prince produced and Robbins directed and choreographed. Set in Czarist Russia, the Bock-Harnick musical starred Zero Mostel as the Jewish milkman forced to confront challenges to his way of life.

Prince had gotten his first opportunity to direct on Broadway in 1962. The musical was “A Family Affair” and its Broadway run was short — only 65 performances — but it gave Prince a chance to work with composer John Kander.

Four years later, Kander would provide the music for one of Prince’s biggest successes, “Cabaret,” based on Christopher Isherwood’s “Berlin Stories.”

And it was “Cabaret” that established Prince as a director of first rank. With its use of a sleazy master of ceremonies (portrayed by Joel Grey), the musical juxtaposed its raunchy nightclub numbers with the stories of people living in Berlin as the Nazis rose to power in the 1930s.

As he became more interested in directing, he withdrew from producing altogether.

Among his more notable achievements: “On the Twentieth Century” (1978) and two of Lloyd Webber’s biggest hits, “Evita” (1979), starring Patti LuPone as the charismatic Argentinian, and “The Phantom of the Opera,” in London (1986), New York (1988) and around the world.

Prince is survived by his wife of 56 years, Judy; his daughter, Daisy; his son, Charles; and his grandchildren, Phoebe, Lucy, and Felix.