Actors and filmmakers have been paying tribute to James Gandolfini, who died suddenly at the age of 51, in Rome.

The star of the HBO hit “The Sopranos” died while on vacation with his teenage son Michael when the tragedy struck. It is believed that Gandolfini suffered from a heart attack, however a medical examination is underway.

The New Jersey native has a nine-month-old daughter Liliana, with his wife Deborah Lin. His first wife Marcy Wudarski immediately travelled to Rome to be with her son.

David Chase, the creator of “The Sopranos” called Gandolfini a “genius” and compared him to “Mozart”.

He said, "James 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. 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.”

Chase continued, "For [wife] Deborah and [son] Michael and [daughter] Liliana his death 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."

Edie Falco, who played Gandolfini’s wife Carmela in “The Sopranos” said, “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."

Carlow native and Oscar-nominated starlet Saoirse Ronan filmed “Violet & Daisy” with Gandolfini in 2011. Ronan described the larger than life actor as “the best”.

She said, “He's so cool and I think when he came on set everyone was aware that Tony Soprano was there, just because of the kind of force Jim is.”

"He's the nicest guy and he was so protective over me and really looked after me."

"I loved the scenes that I had with him—these scenes with long dialogue we had together. It was just a great experience getting to work with an actor like that who really doesn't take any of the bull at all, he's very much about work and that's the main thing for him."

The Governor of Gandolfini’s home state New Jersey, Chris Christie, said, “It's an awful shock. James Gandolfini was a fine actor, a Rutgers alum and a true Jersey guy. I was a huge fan of his and the character he played so authentically, Tony Soprano. I have gotten to know Jimmy and many of the other actors in the Sopranos cast and I can say that each of them are an individual New Jersey treasure. Mary Pat and I express our deepest sympathies to Mr. Gandolfini's wife and children, and our prayers are with them at this terrible time."

Steve Carell, who recently appeared alongside Gandolfini in the comedy “The Incredible Burt Wonderstone” tweeted that the news was "unbelievably sad news".

He told the BBC, “If you watch his work in anything, he is so specific in his characterisations - I think he was a genius.

"When I had a chance to work with him, everyone I know was jealous because this guy was the real deal - he was a consummate actor but apart from that, an incredibly generous good man."

Russell Crowe tweeted: “Sad to hear about James Gandolfini. First met Jimmy back in ‘94. He was roommates in NY with Lennie Loftin. Lovely man. RIP Jimmy.”

Susan Sarandon, who starred opposite Gandolfini in 2005 film Romance & Cigarettes, wrote, “So sad to lose James Gandolfini. One of the sweetest, funniest, most generous actors I’ve ever worked with. Sending prayers to his family.”

The world has been shocked by Gandolfini’s sudden death as he was in good spirits, the Sun reports. Gandolfini was planning a new tattoo as well as a new TV series on HBO.

However the 300lbs actor was forced to admit he had big appetites during his divorce from Marcy Wudarski in 2002 when it was revealed he was a sex-loving cocaine addict. At the time he was forced to enter rehab but said it was a “problem that existed in the past”.