James Gandolfini, most known for his portrayal of an emotionally complex crime boss in HBO's hit series "The Sopranos," has died of a heart attack. The actor was 51.

Gandolfini was universally praised for his work on "The Sopranos." For six seasons, viewers lived vicariously through the chaotic and corrupt life of mobster and "waste management" executive Tony Soprano in suburban New Jersey, along with his wife and two kids, and a few shady associates along the way. Gandolfini executed his role seamlessly. His character was brutal yet gentle, impatient yet stoic, a complicated and tortured soul that drew millions of viewers to the show each week. Many attribute Gandolfini to setting the precedent for other emotionally disturbed characters such as "Mad Men's" Don Draper and "Breaking Bad's" Walter White.

Gandolfini died while on vacation in Rome, Italy. His managers commented, "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." He was expected to attend the Taormina Film Festival in Sicily this weekend to receive the Taormina City Prize. Organizers of the event say they are putting together a tribute to commemorate the actor.

Gandolfini leaves behind many friends and colleagues who had much to say about his personal character as well as his skills as an actor. "He was a genius. Anyone who saw him even in the smallest of his performances knows that," said "Sopranos" creator David Chase in a prepared statement. "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." Gandolfini's "Sopranos" co-star, Joe Gannascoli - who played Vito Spatafore on the HBO drama - expressed his sorrow over his death. "Fifty-one and leaves a kid - he was newly married. His son is fatherless now. ... It's way too young," he said. Chris Albrecht, the former chairman and CEO of HBO who helped developed "The Sopranos," said, "He was a great talent but an even better man. My thoughts are with his family."   Edie Falco, Gandolfini's wife on the show, said in a statement, "I am shocked and devastated by Jim's passing. He was a man of tremendous depth and sensitivity, with a kindness and generosity beyond words. I consider myself very lucky to have spent 10 years as his close colleague. My heart goes out to his family. As those of us in his pretend one hold on to the memories of our intense and beautiful time together. The love between Tony and Carmela was one of the greatest I've ever known."

Gandolfini achieved many accolades in his short life. He garnered enormous praise for his acting, winning both the Primetime Emmy Award for Outstanding Lead Actor in a Drama Series and Screen Actors Guild Award for Outstanding Performance by a Male Actor in a Drama Series three times, among numerous other awards. After "The Sopranos" ended its run, he received a Tony nomination for his role in the Broadway hit, "God of Carnage."

He is survived by his wife, Deborah Lin, his daughter Liliana, and his son, Michael, from a previous marriage.