Says Digital Spy, "The 87-year-old actor reportedly died of natural causes at Juravinski Hospital in Hamilton, Ontario.... Frid also starred in 1973 television movie The Devil's Daughter and 1974 film horror Seizure. He filmed a cameo appearance - his final acting credit - in Tim Burton's forthcoming film remake of Dark Shadows, which stars Johnny Depp as Barnabas."
On a personal note, as a child in the 1960s, Jonathan's portrayal of Barnabas really struck a chord with me and inspired my imagination in such a way that it ultimately led me down the path to writing.
Just as importantly, in the 1980s I interviewed Jonathan in his New York apartment, and for a time was visiting him each Sunday to go through his archives to gather information on a book I was researching, and to reflect with him about those days. It was certainly surreal to know that one Sunday Jonathan Frid would be buying me breakfast or lunch, and on another Sunday I would return the favor.
Perhaps the greatest compliment I got from him was when I wrote my first profile on him and presented it to him when it came out in print. I read it over and commented, "It feels as though you truly got to know me.... I'm a little uncomfortable that you got to know me so well."
Here's an excerpt from that interview, which I always found interesting:
Jonathan Frid was never a fan of the fang aspect of Barnabas Collins and, in an interview with ye editor, admitted that he felt foolish doing that part of the show. The thing that did appeal to him, however, was the "lie" that served as the foundation of the character in (then) present day Collinwood. "It was Barnabas' lie, that he was pretending to be something that he wasn't, which motivated me more than any other aspect of the role. That pretense was something the actor playing Barnabas had to remember all the time. He got the lust for blood every once in a while, but always what preyed on his mind was the lie. And of course it played right into my lie as an actor. I was lying that I was calm and comfortable in the studio, just as Barnabas was lying that he was the calm, comfortable cousin from England. He wasn't at all. He was a sick, unbelievable creep that the world didn't know about."

MPI Home Video, which has played an integral role in keeping the Dark Shadows legacy alive via the video tape and then DVD release of the entire series, has issued an official statement regarding the passing of Jonathan Frid: “The death of Jonathan Frid today at age 87 has left all of us at MPI deeply saddened,” said Malik Ali, CEO of MPI Media Group, home of the Dark Shadows Series on DVD “As a gifted actor in the role of Barnabas Collins, Jonathan was the heart and soul of ‘Dark Shadows’ and, as recently as last week, was graciously taking part in activities surrounding the series. He never tired of meeting fans and was always excited to hear about new ‘Dark Shadows’ releases. Most recently, Frid filmed a cameo appearance for Tim Burton and Johnny Depp’s upcoming ‘Dark Shadows’ movie, along with fellow original cast members Kathryn Leigh Scott, David Selby and Lara Parker. MPI remains committed to preserving Jonathan’s legacy, and that of everyone who helped make ‘Dark Shadows’ an enduring and beloved phenomenon.”
Here's a tribute in photos to Jonathan Frid:
And now a classic Barnabas scene: