After playing a critical Broadway role in “A Chorus Line,” he helped start the vibrant Off Broadway MCC Theater. TV watchers knew him from “The Sopranos” and “Law and Order.”Robert LuPone, an actor and dancer who originated the role of the driven director-choreographer in the musical “A Chorus Line” on Broadway and later helped run a vibrant Off Broadway theater company known for thought-provoking new works, died on Saturday in Albany, N.Y. He was 76.His wife, Virginia (Robinson) LuPone, confirmed the death, at a hospice near his home in Athens, N.Y. She said the cause was pancreatic cancer.Mr. LuPone was familiar to television audiences from his roles on “The Sopranos” and the “Law & Order” franchise. But his first love, like that of his sister, Patti LuPone, was the theater.By 1975, when Mr. LuPone auditioned for “A Chorus Line,” he had been dancing since childhood and had been in a few Broadway shows. Initially cast as Al, one of the dancers vying for a spot in the chorus line of a Broadway musical, Mr. LuPone persuaded Michael Bennett, who conceived and directed the show, that he could play the director, Zach, after Barry Bostwick, who had been cast in the part, left the show during the workshop phase.“Michael has trouble directing actors,” Mr. LuPone said in an interview on the website of the Muny, the musical theater in St. Louis, when it staged “A Chorus Line” in 2017. “No, let me put it this way: Michael has trouble directing egos. He has a tremendous ego. And I have a tremendous ego. Barry Bostwick obviously has a bigger ego than I do.”At the Public Theater, and then on Broadway, “A Chorus Line” was an enormous hit. When it opened at the Shubert Theater — where it would run for 15 years — Walter Kerr wrote in The New York Times that as Zach, Mr. LuPone “retires to a godlike perch at the rear of the auditorium and wheedles out of the brassy and the giggly, the pleading and the nonchalant, snippets of their pasts.”The show was nominated for 12 Tony Awards — Mr. LuPone received a nomination for best featured actor in a musical — and won nine, including best musical. That year, his sister was nominated for best featured actress in a musical, for “The Robber Bridegroom.”“A Chorus Line” proved pivotal for Mr. LuPone: His future was no longer in dancing.Ms. LuPone said that her brother had been an “extraordinary dancer,” and that his decision to give up dancing “haunts me.” In an email, she wrote, “I think he couldn’t take the dictatorial environment that choreographers at that time created.”Mr. LuPone said that dancing in musicals had become a “hollow experience.” In an oral history interview in 2018 with Primary Stages, an Off Broadway theater company, he said, “I wasn’t really able to speak, and the ideas were, for me, superficial.”That realization led him to study at the Actors Studio and perform with the Circle Repertory Company. He began teaching acting at New York University in 1981 and showed a very direct demeanor that his students at first found surprising.“Who was this guy from musical theater talking to us actors?” Bernie Telsey, one of those students, said in a phone interview. “He’d never taught before. But it became the best class ever.” Some students continued to study with him after they graduated.In 1986 Mr. LuPone and Mr. Telsey formed the Manhattan Class Company, which later became MCC Theater. Will Cantler soon joined them as associate artistic director and was named an artistic director in 2011.Over nearly 40 years, the company has sought to produce challenging, original plays and musicals, with a view to what Mr. LuPone called a “third act” — affecting audience members enough to keep them talking about the shows after they returned home.Three MCC productions transferred to Broadway and received Tony nominations for best play: “Frozen,” the story of the aftermath of a 10-year-old girl’s murder, which opened in 2004; “Reasons to Be Pretty” (2008), about people’s obsession with beauty; and “Hand to God” (2014), a dark comedy about a teenager and his profane, possibly demonic sock puppet. An Off Broadway MCC production of “Wit,” Margaret Edson’s play about a woman’s reflections on dying after she learns that she has ovarian cancer — which won the Pulitzer Prize for drama and the Drama Desk Award for outstanding play in 1999 — also moved to Broadway.Mr. LuPone in the 1998 Broadway production of Arthur Miller’s “A View From the Bridge.” He was also a familiar face on “The Sopranos” and “Law and Order.” Sara Krulwich/The New York TimesRobert Francis LuPone was born on July 29, 1946, in Brooklyn and grew up in Northport, N.Y., on Long Island. His father, Orlando Joseph LuPone, was an elementary school principal in Northport. His mother, Angela (Patti) LuPone, a homemaker, encouraged Robert and Patti’s show business ambitions, driving them to classes. Robert and Patti danced together as children, winning third prize at a Jones Beach talent contest.“I still have the trophy,” Ms. LuPone said. “It was a tango.”Robert took tap lessons after school before enrolling in the Martha Graham School, where as a teenager he studied modern dance with Graham, José Limón and Antony Tudor. He attended Adelphi University, on Long Island, but, spurred by meeting a dancer better than he was who had gone to the Juilliard School, he transferred there. He majored in ballet and minored in modern dance and graduated in 1968 with a Bachelor of Fine Arts Degree.By then he had been in the ensemble of a 1966 production of “The Pajama Game” at the Westbury Music Fair (now the NYCB Theater at Westbury) on Long Island. He made his Broadway debut as a dancer in 1968, in “Noël Coward’s Sweet Potato,” and danced in three more Broadway shows before his agent sent him to audition for “A Chorus Line.”Mr. LuPone worked steadily as an actor in theater, in movies and on television. He played the Apostle Paul in the film version of “Jesus Christ Superstar” (1973); was in six daytime soap operas (earning a Daytime Emmy Award nomination for his role on “All My Children”);was seen on series like “Gossip Girl,” “Ally McBeal” and “Billions”; and, between 1997 and 2001, was in Broadway productions of Arthur Miller’s “A View From the Bridge,” Sam Shepard’s “True West” and Herb Gardener’s “A Thousand Clowns.”In six episodes of “The Sopranos,” he played Bruce Cusamano, Tony Soprano’s neighbor and physician, who recommends that Tony see a psychiatrist.In addition to his wife and sister, Mr. LuPone is survived by his son, Orlando, and his twin brother, William.Mr. LuPone’s acting career was secondary to his work at MCC, where he not only developed, oversaw and produced four or five shows a year but also raised money for the theater’s permanent home, the Robert W. Wilson MCC Theater Space, on West 52nd Street in Manhattan, which opened in 2019.“Bob was fearless,” Mr. Telsey said, adding that playwrights often found it hard to accept the candid notes that Mr. LuPone would write them during previews. “They’d be so stressed, but three days later realized that Bobby was right. He pulled no punches.” More