Comedian Garry Shandling, a familiar presence on television who received acclaim for his HBO series “The Larry Sanders Show” and other projects, has died. TMZ.com reports that Shandling, 66, died today at a hospital in the Los Angeles area after suffering a massive heart attack.

The report cites sources who are familiar with the situation, who say Shandling’s heart attack struck without any prior warning.

“A source connected to Shandling says he was healthy and speaking to people on Thursday morning,” TMZ reports, noting that he was taken to the hospital following a 911 call from his home. “We’re told Shandling was alive when he arrived at the hospital,” the report adds.

Shandling had a long career in television, highlighted by his series “The Larry Sanders Show.” The series ran from 1992-1998, chalking up a whopping 56 Primetime Emmy nominations along with many nods for Golden Globes, Directors Guild Awards, Writers Guild Awards, American Comedy Awards and other honors.

Shandling’s own awards included an Emmy for his writing on “Larry Sanders,” awarded in 1998.

Shandling was also known for “It’s Garry Shandling’s Show,” which aired on Showtime from 1986-1990 and received four Primetime Emmy nominations.

He began his TV career as a writer for sitcoms, including “Sanford and Son” and “Welcome Back, Kotter.” Like many comedians of his generation, his break came on “The Tonight Show Starring Johnny Carson,” where he successfully showcased his stand-up act and eventually moved into a gig as a frequent guest host. He was once considered to be among the front-runners to replace Carson.

Here’s Shandling’s first performance on “The Tonight Show,” from 1981 …

Click here to see a video of Conan O’Brien’s tribute to Shandling as O’Brien opened his TBS late-night show “Conan” just hours after news broke of Shandling’s death.