Several shows have musical episodes: Buffy, Scrubs (kind of), Lexx, and I think Alley McVeal. But not Cheers, I don’t think Friends did, and certainly not Seinfeld (not that there’s anything wrong with that). Which show was the first to have a mostly-musical episode, one that was out of character with the show as a whole (i.e., Lawence Welk or Fame were musical shows, not shows with musical episodes)?
Happy Days had a musical episode in 1981. I’m sure there was one before that but it takes it back to at least 30 years ago.
This list might be useful, though it doesn’t include dates or shows with the links:
Wow, The Producer is a 1966 Gilligan’s Island episode. There is a 1955 episode of Producers’ Showcase, but the show’s format is a bit varied to be an anomaly (though I wonder if the GI writers were aware of/making a nod to the show).
For the modern wave (it seems like there are a lot more of them now than in the earlier, happier days), Xena’s The Bitter Suite aired in February 1998. Lexx’s Brigadoom aired in April 1999. Buffy’s Once More with Feeling aired in September 2001, but is ostensibly better known and likelier the trend setter.
The first one that came to mind for me was the Gilligan’s Island episode where they stage a musical version of Hamlet. I wasn’t sure that would count, but it is included in the above list (“The Producer”).
ETA: Whoops, beaten to the punch by Rhythmdvl!
I know that South Park did several musical episodes, including It’s Christmas in Canada and Elementary School Musical.
The Simpsons had one in the late 90s. I don’t recall exactly what happens, just that it starts out with the family watching “Paint Your Wagon,” expecting it to be your standard shoot-em-up western, then becoming horrified when they find out it’s a musical.
Dick van Dyke did several shows with musical numbers, and I’m pretty sure some episodes were essentially musicals.
Apu: Who needs the Quickie Mart? I doooooooooooooooooooooooooooooooo!
Homer: Hey, he’s not happy at all! He lied to us through song! I HATE when people do that!
That’s a clip show, though, not an original musical episode.
I Love Lucy had an episode where they were in Europe, Scotland specifically and Lucy falls asleep and has a dream in the beginning and the rest of the episode is basically a musical.
Back in the 50’s, both *I Love Lucy *and The Danny Thomas Show both had characters with nightclub acts, so they frequently dropped musical numbers into episodes, had guest stars who were pretty much there to sing, etc. Particularly in the early seasons, Andy Griffith found a lot of opportunities to sing along with the Darling family (who were played by The Dillards, an actual bluegrass group.) *The Adventures of Ozzie and Harriet * had several episodes that managed to point out that Ozzie had been a bandleader, Harriet a singer – and of course, managing to shoehorn a song by Ricky in there, as well. I even recall an episode of *I Dream of Jeannie *that managed, somehow, to include a number by the singer-songwriter duo of Boyce and Hart.
And, of course, there were shows like The Monkees, The Partridge Family and some less successful efforts.
It’s not really as rare as you might think.
They even did a whole musical movie.
The Goodies (a BBC program) had a music episode where they did silly comedy songs. That would have been in the mid seventies.
Head of the Class did a musical episode every season in the mid 80’s. The show was a about a group of High School students so it was framed as them doing a musical for the school.
The Drew Carey Show did a musical episode, or at least one with a musical production in it (Time Warp vs Priscilla) in the late 90’s.
Happy Days did a Valentine musical episodein 1978. While it’s not rare to have a lot of music in an episode, I mention the Happy Days eps because, like Buffy and Scrubs, it was an actual musical-episode, i.e. characters bursting into song and choreographed numbers like a Broadway musical and not just “more live music than usual”.
Love Boat did at least one of these also. Like Happy Days it was spectacularly bad.