James Gandolfini

Hollywood was stunned by the sudden loss of James Gandolfini on Wednesday. The Sopranos star — whose other man credits include The Mexican, True Romance, Zero Dark Thirty and Not Fade Away — died of an apparent heart attack while vacationing in Italy. Here's what his co-stars and fellow celebrities had to say about his sudden passing:

The Sopranos' James Gandolfini dies at 51

Terence Winter: "I'm truly crushed at the passing of my friend Jim Gandolfini. He was a gifted, fearless actor, respectful of everyone he met, and extraordinarily generous in every possible way. My heart goes out to his wife and children."

Aida Turturro: "I've not only lost a great friend, but a true brother, on screen and off. James was the most generous actor to work with, but more so, a man with a heart of gold. I love him and my heart goes out to his family."

Jamie-Lynn Sigler: "This news has left me heartbroken. I can only imagine the pain his family feels at this time, and my heart goes out to them, especially Deborah, Michael, and Liliana. I spent 10 years of my life studying and admiring one of the most brilliant actors, yes, but more importantly, one of the greatest men. Jim had the ability, unbeknownst to him, to make you feel like everything would be alright if he was around. I treasure my memories with him and feel so honored that I was an up close witness to his greatness."

Michael Imperioli: "Jimmy treated us all like family with a generosity, loyalty and compassion that is rare in this world. Working with him was a pleasure and a privilege. I will be forever grateful having had a friend the likes of Jimmy."

Edie Falco: "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."

Lorraine Bracco: "We lost a giant today. I am utterly heartbroken."

Steven Van Zandt: "I have lost a brother and a best friend. The world has lost one of the greatest actors of all time. Maureen and I send our deepest sympathy and love to Deborah, Michael, Lily, and all of Jimmy's family."

Jeff Daniels: "If Broadway has a version of a guy you want in your foxhole, Jim Gandolfini was mine. During our time together in God of Carnage, we played 320 performances together. He didn't miss one. Sadly, I now miss him like a brother."

Bryan Cranston: "I'm saddened by James Gandolfini's passing. He was a great talent & I owe him. Quite simply, without Tony Soprano there is no Walter White."

VIDEO: Remembering James Gandolfini

Steven Zaillian: "I worked with Jim before The Sopranos and after it, and throughout these many years he has always been the same man. A real man, like they don't make anymore. Honest, humble, loyal, complicated, as grateful for his success as he was unaffected by it, as respectful as he was respected, as generous as he was gifted. He was big, but even bigger-hearted. I'm so saddened to lose my friend, and sadder still for his family."

Susan Sarandon: "So sad to lose James Gandolfini. One of the sweetest, funniest, most generous actors I've ever worked with. Sending prayers to his family."

Mia Farrow: "Awful, awful news. James Gandolfini  will be missed.  He was a great actor.  Just great."

Christina Applegate: "I am so deeply saddened by the untimely passing of sweet James Gandolfini! My heart is broken for his family!! I'm in shock."

Rob Lowe: "James Gandoldini gave the greatest performance in the history of television. He was also a kind man. Condolences to his family."

Damon Lindelof: "James Gandolfini. You created an icon. And you cut to black way too abruptly. Thank you, and rest in peace."

Olivia Wilde: "James Gandolfini was a kind, funny, wonderful guy. I'm so lucky to have worked with him. Sending love to his family. Such a sad, sad day."

Steve Carell: "James Gandolfini. What a great loss."

Rainn Wilson: "Arrivederci, James Gandolfini. You were one of the great greats. We'll miss your dangerous, big heart. #RIPGandolfini"

Debi Mazar: "Husband informed me that #JamesGandolfini just passed in Italy. I'm devastated. My condolences to his family & friends. He passed in his motherland"

Remember other celebrities we lost this year

Bryan Fuller: "REST IN PEACE, MR. GANDOLFINI"

Greg Grunberg: "Terribly Sad News: R.I.P. James Gandolfini"

Carson Daly: "SO SAD! PRAYING FOR HIS FAMILY- wow- Shocked by this news today...."

Alyssa Milano: "Rest in peace, Mr. Gandolfini."

Jorge Garcia: "So sad. James Gandolfini you will be missed."

David Krumholtz: "R.I.P James Gandolfini. Devastating news. Profound talent gone too soon."

Jonah Hill: "I'm truly heartbroken to hear that James Gandolfini has passed away. He is one of my all-time favorite actors. Tragic loss."

Busy Philipps: "So sad to hear about James Gandolfini. He was such an amazing actor and by all accounts a wonderful person. RIP."

Patton Oswalt: "Bada BULLSH-- G'bye, Gandolfini. This sucks."

PHOTOS: Look back on the life of James Gandolfini

Martha Plimpton: "No. No no no. So awful."

Russell Simmons: "Not Tony Soprano! Damn. Such a good guy and a great actor. James, rest in peace."

Kristen Johnston: "James Gandolfini was one of the sweetest, loveliest men. He loved theater. I saw him @ Xmas & we laughed so hard. A great, great loss."

Joseph Morgan: "I just heard the sad news. James Gandolfini has died. His speech in True Romance defined the metamorphosis of cold-blooded killer for me."

Brian Baumgartner: "I am shattered by the news of the loss of my longtime hero and new friend, James Gandolfini. My thoughts and prayers go out to his family."

Michael Chiklis: "James Gandolfini. This is a tremendous loss. A brilliant actor and a wonderful man. Our deepest sympathies to his family. Devastating."

Katey Sagal: "Speechless. James Gandolfini. Really sad... Hug the kids."

Denis O'Hare: "So sad to hear about James Gandolfini - a lovely man I had the pleasure of working with once. So funny. So humble. So talented."

Watch John Travolta remember his frequent co-star Gandolfini on Good Morning America Thursday: