James Gandolfini, the actor who most famously portrayed Tony Soprano on the series "The Sopranos," has died in Italy at age 51.
"It is with immense sorrow that we report our client James Gandolfini passed away today while on holiday in Rome, Italy," said his managers, Mark Armstrong and Nancy Sanders. "Our hearts are shattered and we will miss him deeply. He and his family were part of our family for many years and we are all grieving."
Gandolfini died while vacationing in Rome and a cause of death has not been given. Gandolfini was expected to attend the Taormina Film Festival in Sicily this weekend and receive the "Taormina City Prize." Instead, organizers of the festival said they're putting together a tribute to the actor.
Organizers Mario Sesti and Tiziana Rocca told The Associated Press they had spoken to Gandolfini hours before his death "and he was very happy to receive this prize and be able to travel to Italy."
Though he rose to his greatest fame playing a New Jersey mob boss on "The Sopranos," Gandolfini also had a long and diverse list of credits as a stage and film actor, including many character and supporting roles.
"He was a genius. Anyone who saw him even in the smallest of his performances knows that," "Sopranos" creator David Chase said in a prepared statement this evening. "He is one of the greatest actors of this or any time. 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. ... 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."
After "The Sopranos" ended its run in 2007, Gandolfini received a Tony nomination starring in the Broadway hit, "God of Carnage," described in a 2009 New York Times article as a "satiric comedy."
Gandolfini told The Times in 2009 that he had been looking for an acting change of pace.
"I love hearing people laugh," he told the interviewer. "Especially in New York, and especially now. To hear somebody out there just belly-laughing."
Recent film roles included his portrayal of CIA Director Leon Panetta in "Zero Dark Thirty" -- and he also appeared in "Killing Them Softly" and "The Incredible Burt Wonderstone," and reunited with Chase to play the father of an aspiring musician in the film, "Not Fade Away."
Matt Zoller Seitz, a TV critic for New York magazine who interviewed Gandolfini in the earliest days of "The Sopranos," told ABCNews.com of Gandolfini's body of work, "You will never catch him doing anything false, ever."
"His technique was impeccable and, like Spencer Tracy used to say: Never let them catch you acting," Seitz said. "James Gandolfini never let them catch him acting."
Beyond acting, Seitz said Gandolfini made an impression on him as "just a good man" who never forgot his roots.
"He wasn't one of them. He was one of us," Seitz said.
HBO, which broadcast "The Sopranos," said in a prepared statement, "We're all in shock and feeling immeasurable sadness at the loss of a beloved member of our family. He was special man, a great talent, but more importantly a gentle and loving person who treated everyone no matter their title or position with equal respect. He touched so many of us over the years with his humor, his warmth and his humility. Our hearts go out to his wife and children during this terrible time. He will be deeply missed by all of us."
Gandolfini told the Newark Star Ledger in a December 2012 interview that he was glad "The Sopranos" ended in 2007 after six seasons.
"You know, at no point, even at this point, have I ever said I wish I was still doing it. I've never missed it -- which makes me think it was definitely time for it to end," he said. "Obviously it was great, and the people we worked with were great, but we'd said everything we could, we'd done everything we could, it was time for everybody to move on. For us to go another year would have been a big mistake."
Born on Sept. 18, 1961 in Westwood, N.J., Gandolfini cultivated an interest in theater while he was still in high school, and then went on to study communications at Rutgers University.
There, he met celebrity chef Mario Batali, who became a lifelong friend.
"I am totally shocked and devastated by the passing of one of my oldest and dearest friends," Batali told ABC News. "I only hope to help his family any way I can in their grief and mourning."
Gandolfini is survived by his wife, Deborah Lin, his daughter Liliana, 8 months, and his son, Michael, from a previous marriage.
After getting his start in the 1987 film "Shock! Shock! Shock!" Gandolfini went on to play a Virgil, a mob-enforcer in "True Romance" in 1993 and a lovable bodyguard in "Get Shorty," before landing the role of a lifetime, Tony Soprano, a few years later.
"I have lost a brother and a best friend," tweeted Steven Van Zandt, who co-starred with Gandolfini on "The Sopranos." "The world has lost one of the greatest actors of all time."
"Jimmy was a dear friend and like a brother to me. He was a great actor and a great father," said another of his "Sopranos" co-stars, Steve Schirripa. "I will miss him terribly. I am very sad."
ABC News' Anthony Castellano contributed to this report.