Richard Belzer, stand-up comedian, best-selling author, and Law & Order veteran, has died, his literary agent David Vigliano confirms to ABC News. A cause of death is not yet known.
Belzer was one of the few actors to play the same character across several television shows: His cynical, conspiracy theory-loving Detective John Munch began on the NBC cop drama Homicide: Life on the Street from 1993 to 1999 before being spun off to Law & Order: Special Victims Unit, in which he appeared from 1999 to 2013.
The character, however, popped up in shows ranging from The X-Files to Arrested Development.
Belzer got his start in comedy, working alongside Saturday Night Live legends like John Belushi, Gilda Radner and Bill Murray in the National Lampoon Radio Hour in from 1973 to 1975, and appeared on camera in shows from Sesame Street to Saturday Night Live, for which he served as a warm-up comedian in the show's early days.
Belzer also appeared in movies including Fame, Scarface, and Night Shift, as well as music videos for Mike + The Mechanics and Pat Benatar, and over the years often returned to the radio mic, at one point hosting a show for the liberal network Air America.
The actor also wrote four books regarding conspiracies, from the JFK Assassination to the 2014 disappearance of Malaysia Airlines Flight 370 and the novels I Am Not a Cop! and I Am Not a Psychic!.
Belzer was memorialized on Twitter by original Saturday Night Live cast member Laraine Newman, who noted, "...I loved this guy so much. He was one of my first friends when I got to New York to do SNL. We used to go out to dinner every week at Sheepshead Bay for lobster. One of the funniest people ever. A master at crowd work. RIP dearest."
His SVU co-star Mariska Hargitay wrote on Instagram, "Goodbye my dear, dear friend. I will miss you, your unique light, and your singular take on this strange world. I feel blessed to have known you and adored you and worked with you, side by side, for so many years."