TV series with full cast turnover (any sitcoms?)

The occasional long-lived TV series undergoes a complete turnover in the starring cast over the course of its run. A prominent example that springs to mind is Law & Order, which, with the departure of Steven Hill in its 11th season, no longer had any of the main first-season cast members.

Can anyone think of any further examples? I’d be particularly interested to know if this phenomenon has ever occurred with sitcoms, as opposed to dramas.

For the purposes of this question, let’s consider only fully scripted works of fiction (i.e., no documentary series, educational programs, game shows, reality TV, news programs, etc.), and only those which are intended to have a steady cast playing recurring characters (so no anthology series or movie-of-the-week shows).

Also, have any such shows had a turnover faster than Law & Order’s 11 years?

The nationally broadcast version of Mystery Science Theatre 3000 lost its last original cast member (out of 4) in the middle of season 8 when Jim Mallon stopped voicing Gypsy.

ER lost its last original major character, Dr. Carter, at the end of season 11. (He did come back a few times in seasons 12 and 15.) Of the 83 characters listed on Wikipedia’s timeline of Cook County General staff, only two appeared in all 15 seasons: nurses Haleh Adams and Malik McGrath.

Doctor Who probably shouldn’t count, but it looks like all the original companions were gone by the time the First Doctor regenerated in season 4. (I don’t know if there are other characters that lasted longer.)

I’d guess a lot of the super-long-running soap operas would qualify as well, but I don’t know them well enough to say which ones do.

Law and Order Criminal Intent sort-of had a full cast turnover. But Vincent D’Onofrio and Kathryn Erbe came back for the last (short) season.

NCIS comes pretty darn close. The only original full time cast member left, I believe, is Mark Harmon. McCallum is kind of part time these days because of age. “McGee” came on the scene 16 episodes in, I believe.

Saturday Night Live, although that’s arguably a special case.

I think most sketch comedy shows fall short of the “only those which are intended to have a steady cast playing recurring characters” rule. Maybe something like Little Britain would be acceptable, since it relies on a fixed stock of characters for pretty much all the sketches. (Though of course it fails the main rule, since it never had a full turnover.) I haven’t seen Saturday Night Live myself, though I understand it’s a mix of sketches with recurring characters and self-contained sketches with one-off characters (not to mention segments that aren’t fictional at all, such as musical guests).

I’d still count Law & Order: Criminal Intent; as long as there’s at least one season with no main cast members from the first season, it meets the rule.

What about Law & Order: Special Victims Unit? I see that’s still on the air after more than 20 years. Is anyone from the first season still left?

“The Avengers” is a near-case. John Steed was not a regular in the first season of the series (he missed a couple of episodes entirely) - but by the end of the series he was the only first-season character left.

Not quite fitting the OP for this one, but a very odd case. The sitcom Duet made a rapid and ungainly transition into a new show called Open House. The new show had mostly the same actors and characters initially, but over the course of it’s short life only Alison La Placa and Ellen Degeneres remained. And Ellen had only been in one episode of Duet, her first TV credit. Duet was a romantic comedy while Open House was about a realtor’s office. So a complete name change, plot change, and by the end of it’s first and only season a near complete cast change based on the same TV universe of characters.

I can’t think of any sitcoms that completely replaced the cast without also rebooting the show so substantially that it isn’t the same show anymore. But I can think of at least three that came close.

The Doris Day Show changed format and setting pretty much every season, and the star was the only cast member from beginning to end.

Tea Leoni must have had a very specific clause in her contract that she would only act in a show titled The Naked Truth, which also changed the setting and supporting cast.

Cleavon Little (pre-Blazing Saddles) failed to gel with James Whitmore in a hospital sitcom called
Temperatures Rising, so the producers replaced Whitmore with Paul Lynde, and got rid of the original supporting cast (although some of them returned in the third season.)

If you call Mayberry R.F.D. as a continuation of The Andy Griffith show then it would have a full cast turnover. But, I consider it a spin-off so it wouldn’t count.

It definitely was a spin-off. A lot of the Andy Griffith show characters continued on RFD. Andy himself was only in a handful of episodes. Jack Dodson and Paul Hartman (Howard Sprague and Emmet Clark) were on frequently and had most of their appearances on Andy Griffith in the latter seasons. Many other Mayberry denizens appeared on both shows.

Law & Order nearly had two full turnovers, depending on how you look at it. For example, the ADA role went from Michael Moriarty to Sam Waterston to Linus Roache. The part of the ranking police officer only changed once, from Dann Florek to S. Epatha Merkerson.

Sam Waterston stayed through the final season, playing the same character, but moved from ADA to District Attorney, so there was a shift in where he fit within the procedural nature of the show.

Mariska Hargitay is still hanging in there.

If you’re counting UK series, then Midsomer Murders fits. It’s up to 21 seasons; the last original cast menber left in season 14.

Death in Paradise a BBC detective dramedy has 2 recurring characters still there, (the commissioner and the original DS’s mother) but they are pretty minor compared to the main cast and don’t appear in most episodes.

The main cast are the DI (replaced 3 times)
The DS, the diligent offcer and the lazy officer (all replaced once)


Coronation Street?

-delete- already mentioned above!

Robotech had 2 different full cast turn overs IIRC but that was because Robotech was a 70 episode American series made by taking 3 seperate Japanese animes and stitching them together and pretending the new characters were part of the same organization as the original ones. I’m fairly certain this has also been done as well in other American series, taking two different foreign shows and combining them pretending theres an actual connection between the two.