Harold Prince, 91, the musical theater producer and director whose Broadway portfolio included West Side Story, Fiddler on the Roof, Cabaret, Sweeney Todd, Evita, and The Phantom of the Opera, died Wednesday, July 31, in Reykjavik, Iceland, where he was traveling.

His death was confirmed by a publicist, Rick Miramontez. No other details were immediately available.

In addition to being a force on Broadway — with 21 Tony Awards during a career spanning seven decades — he was a noteworthy and generous University of Pennsylvania alumnus, and Philadelphia’s landmark Prince Theater was named in his honor.

Mr. Prince, known as “Hal,” graduated from Penn’s College of Arts and Sciences in 1948 at age 19. As a student, he won awards for acting and writing with the Pennsylvania Players, a student theatrical group. He also managed WXPN, the campus radio station that he helped found.

By granting the royalties from Cabaret to the university, he helped fund the construction of the Prince Theater in the Annenberg Center for the Performing Arts in 1968. At the time of its founding, the Prince Theater was meant to be an experimental theater with “movable seats and staging to permit free exploration of audience-performer relationships,” according to an Inquirer article published in 1968.

A second theater was named for the theater giant in 1999 — the Prince Music Theater at Broad and Chestnut Streets. It hosted the world premiere of The Sixth Sense as well as 92 world premieres of musicals before closing in 2014. In 2015, the Philadelphia Film Society acquired the building and renamed it the Prince Theater, and in October last year it became the Philadelphia Film Center.

Also in 2015, Mr. Prince won the Creative Spirit Award, which is given to a member of the Penn community who has demonstrated a lifelong commitment to the arts. At the award ceremony, Dan Kutner, theater director and assistant director for the Harold Prince Organization, called Prince a “force of nature.”

An important mentor to Broadway talent, Mr. Prince gave major early breaks to some of the towering songwriting teams on Broadway: Richard Adler and Jerry Ross (The Pajama Game, Damn Yankees); Jerry Bock and Sheldon Harnick (Fiddler on the Roof, Fiorello!, Tenderloin, She Loves Me); and Fred Ebb and John Kander (Cabaret, Kiss of the Spider Woman, Zorba). He also boosted the career of young composer-lyricist Jason Robert Brown, whose Parade (1998) — about a notorious anti-Semitic lynching in Georgia in 1915 — won two Tonys.

Mr. Prince was a recipient of the Kennedy Center Honors in 1994, the National Medal of Arts in 2000 and a lifetime achievement Tony in 2006. In 2017, a career retrospective called Prince of Broadway had a short run on Broadway to poor reviews.

In the new century, Mr. Prince’s lifelong interest in new material was clearly out of sync, as Broadway grew crowded with movie adaptations and pop-catalog shows.

“I’m a big believer — and sometimes I feel I’m almost alone in this — that you can and should do what you want to do and bring the audience with you rather than have them lead you,” he told the Hartford Courant in 2005. “I think that’s one of the problems with the commercial theater right now. Everyone’s dealing with surveys and demographics and what worked last year and all the rest of it — and it’s a very bad way to create a show. It’s art, for God’s sake. Yes, it’s commerce, too, but you can’t lose sight of the art. Who else [but an artist] would do Fiddler? Was the market there desperate to hear the Tevye stories?”

In 1963, Mr. Prince married Judy Chaplin, daughter of Oscar-winning songwriter, producer, and musical director Saul Chaplin. Besides his wife, survivors include children Charles and Daisy, and three grandchildren.

A champion of ‘new work’

The composer Stephen Sondheim — another beneficiary of Mr. Prince’s support — told the New York Times in 2000 that Mr. Prince was “one of the very few champions of new work in the commercial theater. New writers are interested in expanding the possibilities, and most musical theater producers are interested in shrinking them.”

Mr. Prince was 26 when he co-produced his first show on Broadway, The Pajama Game (1954). With songs including “Hey There” and “Steam Heat,” it brought an appealing song-and-dance style, as well as romance, to a plot line about a labor strike at a pajamas factory. The combination helped secure the Tony for best musical and presaged the social concern that would characterize much of Prince’s work.

The overnight Broadway wonder then hit another home run: the baseball-meets-Faust story Damn Yankees (1955). Two years later, he provided essential backing for West Side Story, which retold Shakespeare’s Romeo and Juliet against the backdrop of warring New York street gangs.

Even the risk-embracing Mr. Prince admitted to having had reservations about the potential commercial appeal of Fiddler on the Roof (1964), based on Sholem Aleichem’s Yiddish stories about a shtetl milkman, Tevye, and his willful wife and daughters in czarist Russia.

Mr. Prince presented the rise of fascism in Weimar Germany through the lens of a dingy, decadent nightclub with a sinister master of ceremonies in Cabaret (1966). He also mined rich political metaphors in Fiorello! (1959), about New York City Mayor Fiorello La Guardia, and Evita (1979), about Eva Perón, the scheming, image-conscious wife of an Argentinian dictator.

The Prince-Sondheim collaboration included the hit farce A Funny Thing Happened on the Way to the Forum (1962), starring Zero Mostel, before moving in daring new directions just a few years later. They largely created what many critics dubbed concept musicals — works in which the plot was constructed around themes or ideas. Narrative structure was often inventive. Merrily We Roll Along (1981), a tale of a broken friendship, was told in reverse to show how a bitter end can return to optimistic beginnings.

The partnership resulted in many shows that, while not always fully appreciated at first, are today regarded as landmarks in modern musical theater. They included Company (1970), a meditation on marriage; Follies (1971), about a reunion of aging chorus girls (an expensive flop at the time); and A Little Night Music (1973), based on the filmmaker Ingmar Bergman’s romantic roundelay, Smiles of a Summer Night.

Sondheim’s idea for the genre-pushing, near-operatic Sweeney Todd: The Demon Barber of Fleet Street (1979), about a barber and a baker who engage in murder and cannibalism, was initially too small and darkly conceived for Mr. Prince’s taste. “It wasn’t until he thought of doing it in that epic way that he got interested,” Sondheim said. “The whole point is not to be bored.”

‘The show that freed me’

Harold Smith Prince was born in New York City on Jan. 30, 1928, the only child of what he called a “privileged, upper-middle, lower-rich class Jewish family.” His father was a Wall Street stockbroker, and his mother was an avid theatergoer. Mr. Prince was captivated by the stage when he saw Orson Welles’ 1937 Broadway staging of Julius Caesar.

Mr. Prince entered Penn with the intention of becoming a playwright. After graduating in 1948, he hustled his way into a low-level job with George Abbott, the writer-producer-director whose Broadway credits spanned the 20th century and who remained a trusted adviser until his death at 107 in 1995.

Mr. Prince’s rapid advance to Abbott’s assistant stage manager was interrupted by two years of Army service in West Germany, but he returned eager to make his mark in theater. When the Times gave a rave review to Richard Bissell’s novel 7½ Cents, he optioned it the next day.

With two partners, Mr. Prince produced a musical based on the book. They recruited Abbott to write the show with Bissell and co-direct it with Jerome Robbins, and they gave a young Bob Fosse his first job as a choreographer. They also hired themselves as stage managers. “We needed the money,” Mr. Prince joked.

The producers lined up 164 investors because “none of the smart money would support us,” Prince recalled. The Pajama Game, starring John Raitt and Janis Paige as the romantic leads, ran for more than two years. Mr. Prince also shared his first Tony Award for best musical.

The next several years resulted in smashes (Damn Yankees, in 1955, harvested seven Tonys) and flops (New Girl in Town, 1957, a musical based on Eugene O’Neill’s waterfront melodrama Anna Christie). Through it all, Mr. Prince was a dervish of creative impatience.

From Abbott, he adopted the trick of moving quickly from one project to the next, setting up meetings to discuss a new show the day after an opening. "No matter what happens," he explained to Time magazine, "you feel you are still working."

West Side Story — about rival white and Puerto Rican gangs — had been germinating for years among the playwright Arthur Laurents, director-choreographer Robbins, the composer Leonard Bernstein, and lyricist Sondheim.

In 1957, weeks before rehearsals began, a key producer withdrew amid financial concerns. Other backers, doubting the appeal of a show in which most of the lead characters die, failed to materialize. Robbins, already a marquee name, wanted out.

Sondheim called on his friend Mr. Prince, who immediately agreed to step in. He persuaded Robbins to stay and complete the show’s signature gangland ballets.

Despite solid reviews, the show lost most of the Tony Awards that year. Only after the 1961 film version, which dominated the Oscars, did West Side Story become one of the all-time champs of musical theater.

Mr. Prince began directing shows in the early 1960s and had mixed luck — a combination of pedestrian material and sometimes-tense relations with veteran actors who liked to test his knowledge of stagecraft. But he spoke of Cabaret as a turning point in his confidence — a show where he knew everything he wanted from the performers. He also created the musical’s atmosphere, its visceral sense of cheap debauchery.

"That's the show that freed me," he later told Playbill. "I remembered when I was in the Army in 1951, I went to a sleazy nightclub in Stuttgart in the basement of a bombed-out church, and there was this emcee all made up. We put that character into the show, making him represent Germany, and made him a metaphor for National Socialism."

In a career-defining part, Joel Grey played the master of ceremonies. But Mr. Prince — who won a Tony for directing — had a strong distaste for “star vehicles.” He emphasized the ensemble over any particular actor, creating a show unlike Fosse’s 1972 film version that put Liza Minnelli, as a complicated American dancer, squarely at its center.

The biggest box-office draw of all time

As a producer, Mr. Prince endured a long succession of high-profile flops in the late 1970s and 1980s. The songwriters Andrew Lloyd Webber and Charles Hart then almost single-handedly revived Mr. Prince’s reputation when they asked him to direct The Phantom of the Opera, which opened in London in 1986 and on Broadway in 1988. He had earlier directed the Lloyd Webber-Tim Rice Evita, a rock-filled hit featuring Patti LuPone.

In Phantom, Mr. Prince was credited with emphasizing the title character’s sensuality and intelligence instead of slushy melodrama, as well as giving the show what he called a “mysterious, perfumy atmosphere.”

"I wanted the show to have some depth," he told New York magazine. "I wasn't looking to do Dracula with music."

His romantically dark, cinematic staging featured the spectacle of a chandelier crashing to the stage and a chase to a lake beneath the opera house. The show, still running on both sides of the Atlantic, has become the biggest box-office draw of all time.

As a director, Mr. Prince also took a rare stab at a revival with a major reconsideration in 1994 of Jerome Kern and Oscar Hammerstein II’s 1927 Show Boat. Mr. Prince’s version, with a cast of more than 70 and a budget of $8.5 million, ran for three years and garnered a Tony for best musical revival.

Staff writer Bethany Ao contributed to this article.