Actor James Gandolfini, who rose to fame as mob boss Tony Soprano on the hit HBO drama "The Sopranos," died Wednesday of a possible heart attack while visiting Rome. He was 51.
Antonio D'amore, director of the Italian capital's Hotel Boscolo, said the actor collapsed around 10 p.m. local time (4 p.m. ET).
Gandolfini's son Michael was with him in the hotel room and called for help, according to D'amore. Staff rushed to the room and found him on the bathroom's floor. He was later pronounced dead at a nearby hospital, which is a three-minute drive from the hotel.
"We're all in shock and feeling immeasurable sadness at the loss of a beloved member of our family," HBO said in a statement. "He was a 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 was in Italy to appear as guest of honor at the Taormina Film Festival. The actor's sister was also staying at the Hotel Boscolo.
Gandolfini had appeared in numerous films before landing the role of Soprano, but it was the panic attack-stricken mob boss who would forever define him. He won critical acclaim, three Emmy Awards and three Screen Actors Guild awards for the role, which he played from 1999-2007 on the groundbreaking show.
“He was a genius," said "Sopranos" creator David Chase. "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. 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 (son) Michael and (baby daughter) 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.”
The actor's managers also released a statement. "It is with immense sorrow that we report our client James Gandolfini passed away today while on holiday in Rome, Italy," it read. "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."
Although a New Jersey native, Gandolfini didn't expect to land the role of the head of the New Jersey crime family. "I thought that they would hire some good-looking guy, not George Clooney but some Italian George Clooney, and that would be that," he told Vanity Fair in 2012.
But instead, it was Gandolfini who got the nod, and he made viewers care about a mob boss who could order the murder of a family member one minute and turn around and tenderly feed the ducks that swam in his estate's swimming pool the next.
"I think you cared about Tony because David was smart enough to write the Greek chorus, through (Soprano's psychiatrist) Dr. Melfi," Gandolfini said. "So you sat there and you got to see his motives, what he was thinking, what he was trying to do, what he was trying to fix, what he was trying to become. And then you saw it didn’t really work out the way he wanted it to."
Actress Lorraine Bracco, who played Melfi, said in a statement, "We lost a giant today. I am utterly heartbroken."
Six years ago this month, "The Sopranos" came to an end with a mystifying finale where Tony and family sit in a diner. As an unseen person enters, Tony looks up, and the screen goes blank, forever ending the show. Gandolfini too admitted to a confused reaction to the long-awaited wrapup episode.
"When I first saw the ending, I said, “What the (expletive)?” he told Vanity Fair. "I mean, after all I went through, all this death, and then it’s over like that? But after I had a day to sleep, I just sat there and said, 'That’s perfect.'"
Members of the band Journey, whose 1981 hit "Don't Stop Believin'" was playing in that final scene, mourned Gandolfini's loss Wednesday. "It's truly an honor to have been able to share one of the greatest moments ever in TV history with James Gandolfini," the band said in a statement. "He was an amazing actor -- taken way too young -- and he'll be missed. Our condolences go out to his family."
Fans and fellow actors quickly took to social media to mourn his death.
"I am heartbroken about James Gandolfini," wrote actress Rose McGowan, tweeting a photo of herself with Gandolfini. "He was a gentle giant and great man." The two were part of a group of actors who traveled to Afghanistan in 2010 to support American troops there.
Gandolfini also went on a USO tour to Kuwait and Iraq in 2004, and found himself unable to forget the soldiers and Marines he met there. The result was his 2008 HBO documentary, "Alive Day Memories," in which he spoke with 10 men and women who survived the war. The program was nominated for an Emmy Award for outstanding nonfiction special, and NBC Nightly News anchor Brian Williams called it a "powerful and nonpolitical hour of television."
It wasn't Gandolfini's only work to support the military. He also produced the 2010 HBO documentary "Wartorn: 1861-2010," which examined combat and post-traumatic stress, from the Civil War to modern day.
And Gandolfini was continuing to work busily in both film and television. Just last month, HBO ordered seven episodes of his new project, "Criminal Justice," according to The Hollywood Reporter. His most recent movie role was that of a clueless billionaire casino owner in Steve Carell's "The Incredible Burt Wonderstone," which opened in March, and he played a character based on former CIA director Leon Panetta in 2012's "Zero Dark Thirty."
In a 2009 appearance on "Inside the Actors Studio," host James Lipton asked Gandolfini, "if heaven exists, what would you like to hear God say when you arrive at the Pearly Gates?"
Gandolfini thought for a moment, and as a giant smile slowly broke across his face, cracked, "Take over for a while, I'll be right back!"
NBC News' Claudio Lavanga contributed to this report.