"Sopranos" creator David Chase: "He was a genius. He's one of the greatest actors of this or any time . . . 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."
"Sopranos" star and E Street Band guitarist Steven Van Zandt: "I have lost a brother and a best friend. The world has lost one of the greatest actors of all time." Steven played Silvio Dante on the show . . . the owner of the Bada Bing strip club.
"Sopranos" star Lorraine Bracco: "We lost a giant today. I am utterly heartbroken." Lorraine played Tony Soprano's shrink, Jennifer Melfi, on the show.
"Sopranos" star Joe Gannascoli: "Fifty-one and leaves a kid. He was newly married. His son is fatherless now . . . It's way too young." You know Joe as Vito Spatafore, who was secretly gay, on the show. .
"Sopranos" star Steve Schirripa, who was at a Yankees game when he heard the news: "I had to get up and leave. It was like being told a brother had died. He was as great a friend as he was an actor and a human being . . .
"The phone hasn't stopped. I spoke to a lot of the guys from 'The Sopranos'. We were crying. People joke about us being a family. But we ARE a family."
Jeff Daniels . . . who co-starred with James in the 2009 Broadway production of "God of Carnage": "If Broadway has a version of a guy you want in your foxhole, [he] 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."
Gilles Marini: "R.I.P James Gandolfini. Was an honor to teach your son soccer and to have known you. You were such a great man and father. #Heartbroken." And on Facebook, Gilles added, quote, "Last Saturday, he told me at our kids' graduation that he was so happy to go with his son to Italy. A boy trip! It was an honor to have met this man, such a great Dad!"
New Jersey Governor Chris Christie: "James Gandolfini's passing is an awful shock. He was a fine actor, a Rutgers alum and a true Jersey guy."
Kevin Smith: "Your iconic portrayal of mob boss Tony Soprano gave soul to a monster and fostered perverse pride in the Garden State!"
Ricky Gervais: "Damn. RIP James Gandofini. An amazing actor that made arguably the greatest drama of all time, & a funny, sweet, gentle giant off screen."
Ewan McGregor: "Jesus. The world just lost one of its great actors. James Gandolfini has passed away. Thoughts to his family. Such a talent. I'm saddened."
B.J. Novak: "James Gandolfini on 'Inside the Actors Studio' [is] one of the most inspiring interviews about acting I have ever seen."
Kathy Griffin: "RIP Mr. Gandolfini. If you have [a few minutes, please] enjoy this story about my run-in with this GREAT talent." (She linked to this video from her stand-up routine, where she talks about meeting James. WARNING: It contains UNCENSORED PROFANITY, but you'll be glad you watched it.)
Rose McGowan: "I'm heartbroken about James Gandolfini. He was a gentle giant and great man. I love this picture, I loved him." (And she included this picture of her and James.)
Nancy Sinatra: "James Gandolfini. My favorite picture from my Sopranos shoot, hugged by a big teddy bear. Shocking, brutally sad loss. (She included a picture of her and James, but you can't really see either of their faces.)
And JOURNEY!: "It's truly an honor to have been able to share one of the greatest moments ever in TV history with James Gandolfini. He was an amazing actor . . . taken way too young . . . and he'll be missed. Our condolences go out to his family."