James Gandolfini, who brought a balance of intensity and vulnerability to his portrayal of conflicted mob boss Tony Soprano that made him among the most respected actors of his generation, died Wednesday in Rome. He was 51 and was believed to have suffered a heart attack. According to the Taormina Film Festival, he was on his way to the film festival where he was expected Thursday. He had been expected to participate in an onstage conversation with Italian director Gabriele Muccino on Saturday at the Sicilian festival. Gandolfini’s commanding screen presence was the driving force in establishing “The Sopranos” as the most influential TV show of the past generation. The actor was praised for his deft juggling of the character’s violence and sensitivity, making the murderous crime lord a sympathetic figure that set the mold for the flawed anti-heroes that populate cable dramas today. Underscoring the show’s continuing influence, “Sopranos” was voted the best-written series of all time in a recent Writers Guild of America survey. Gandolfini had an active career in movies, TV and on stage before he inhabited Tony Soprano. But it was the role created by David Chase of the New Jersey mob boss who decides to see a psychiatrist to deal with his emotional issues that catapulted him into mega-stardom. Balding and beefy, Gandolfini was not conventionally handsome but became a sex symbol through the show’s immense popularity. “He was a genius. Anyone who saw him even in the smallest of his performances knows that. He is one of the greatest actors of this or any time,” Chase said in a statement. “A great deal of that genius resided in those sad eyes. I remember telling him many times, ‘You don’t get it. You’re like Mozart.’ There would be silence at the other end of the phone. For (wife) Deborah and (children) Michael and Liliana this is crushing. And it’s bad for the rest of the world. He wasn’t easy sometimes. But he was my partner, he was my brother in ways I can’t explain and never will be able to explain.” Gandolfini later acknowledged that he was surprised to have landed the lead role, given his history as a supporting player. Others considered for Tony Soprano include Anthony LaPaglia. But Chase responded to Gandolfini’s naturalistic style and the authenticity he brought as a native son of New Jersey. Like the character, Gandolfini was known to have a prodigious appetite for eating and drinking.