Gandolfini's cause of death has not been determined, though there are conflicting reports that the actor may have had a heart attack or a stroke [UPDATE: New details emerge]. He was 51 and leaves behind a wife, Deborah, and a daughter, Liliana, born in 2012. He also had a son, Michael, with his former wife Marcella Wudarski.
Van Zandt appeared on HBO's "The Sopranos" during its entire six-season run as the consigliere to Gandolfini's Tony Soprano. His character, strip-club owner Silvio Dante, was routinely the most loyal member of the Soprano crime family. But that isn't to say that Sil never confronted Tony on his flaws (see below).
Gandolfini and Van Zandt, who both grew up in New Jersey, joined up with "Sopranos" creator David Chase earlier this year on the coming-of-age film, "Not Fade Away." Gandolfini starred while Van Zandt acted as musical director.
"The Sopranos" ran from 1999 to 2007 and co-starred Edie Falco, Michael Imperioli and Lorraine Bracco. In the show's final minutes, during which Soprano and his family gather at a local diner, the mob boss puts the Journey song "Don't Stop Believin" on the jukebox. The tension-filled scene, which ends abruptly while singer Steve Perry belts the song's soaring chorus, has gone down as one of the most memorable series endings in TV history.
Following news of Gandolfini's death, the classic rock group passed on their condolences.
"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."