After 20 years, several hundred episodes and appearances on more shows than any other character in American TV history, Detective John Munch is retiring.

On last night's episode of "Law & Order: Special Victims Unit," Munch — played for over two decades across "Homicide: Life on the Street" and "SVU" by comedian Richard Belzer — announced plans to retire from the NYPD. Belzer is leaving the regular "SVU" cast, though showrunner Warren Leight says the plan is to have Much work as an investigator for the district attorney's office, allowing him to make another one or two appearances this season. (This was the career approach the franchise tried to take with Jerry Orbach's Lennie Briscoe when he switched from the "Law & Order" mothership to the short-lived "Trial by Jury," but Orbach passed away after filming only a couple of episodes.)

"This is actually often what happens to respected detectives who hit the NYPD'ss mandatory retirement age," says Leight, noting that cops have to be out by their 63rd birthday. (Belzer is 69.)

Munch began life on "Homicide" as a comic relief character and foil to Ned Beatty's gruff Stan Bolander. (He has perhaps that pilot's most memorable scene, when he accuses a suspect of talking to him like he was Montel Williams.) Though he never moved to the series' forefront, he had some memorable episodes, and in particular hit it off beautifully with Orbach during the first "Homicide"/"Law & Order" crossover. This caught the eye of "L&O" czar Dick Wolf, who happened to be launching "SVU" right as "Homicide" was coming to an end, and decided to have Belzer play Munch on the new show. Again, Munch was a spice rather than the main dish, and his appearances have diminished the last few seasons, but he stuck around for the great majority of 13 seasons, commenting wryly on the case of the week.

At the same time, Munch has popped up in a surprising number of places. Some have involved past and present employers — Belzer guested on "Trial by Jury," and on "Homicide" producer Tom Fontana's short-lived UPN cop show "The Beat," and also let art meet life when he played a scene as Munch opposite retired Baltimore cop Jay Landsman (the inspiration for Munch) in one of the final episodes of "The Wire" — but he's also played the role on "The X-Files" in two episodes of "Arrested Development" and even an installment of "Jimmy Kimmel Live." He also played himself playing Munch in two different episodes of "30 Rock," and played very Munch-esque cops on "Mad About You" and in "A Very Brady Sequel." A Muppet version of Munch (played by puppeteer David Rudman) also appeared in a "Sesame Street" parody, "Law & Order: Special Letters Unit."

All in all, it's been a remarkable run for Belzer and Munch — not the length that James Arness played Matt Dillon on "Gunsmoke," but comparable to Kelsey Grammer's run across two series as Dr. Frasier Crane — and I'm glad to hear that "SVU" isn't entirely done with the character yet.

What does everybody else think? Do you have a favorite Munch moment, among his many appearances on many shows?