This pretty much concerns guest characters who would show up for multiple episodes but were never officially written out or brought back. So this isn't exactly about characters like Chuck Cunningham (https://tvtropes.org/pmwiki/pmwiki.php/ChuckCunninghamSyndrome/LiveActionTV) or Judy Winslow.

Darren from the middle.

Axel’s buddy than Sue’s ex fiancé. After Sue & Darren broke up.

Darren appeared in 1 more episode where Frankie was telling another mom that her older Son Axel was more sociable and they showed Axel, Sean, Darren leaving a football game. Then Darren was never seen again.

Although a year later Frankie mentioned Darren’s name to Sue. Than never talked or seen again.


Even out of the middle I couldn’t find any information on Jon Gammon who portrayed Darren on the middle. (HMM)…



I haven’t gotten to see the show in a long time but Barbra Montgomery who played Sister Cassiestta wasn’t in the last season of Amen.

Lex Luthor and Cat Grant disappeared from Lois & Clark after a season or two.

Alex's best friend Bo (Beau?) and nosy neighbor Mrs. Wilgas (and husband) and snooty rival Lydia disappeared from The Donna Reed Show after season 1 or 2.

All three casts of the various Doris Days Shows (and her kids).

Cousin Pearl and Jethrene.

Darrin's best drinking buddy Dave.

Etta Candy, General Blankenship and Wonder Girl (Drusilla) after season 1 of Wonder Woman.

Yeoman Janice Rand on Star Trek.

Andy Taylor's GF Ellie.

Larry Mondello.

Dick Martin's character on The Lucy Show (and her kids).

Milton Armitage and Thalia Menninger on Dobie Gillis.

Cindy Lee on Isis.

Gordy on MTM.

John on Taxi.

Chuck on Happy Days (maybe it really IS about him).

Lex Luthor and Cat Grant disappeared from Lois & Clark after a season or two.

Alex's best friend Bo (Beau?) and nosy neighbor Mrs. Wilgas (and husband) and snooty rival Lydia disappeared from The Donna Reed Show after season 1 or 2.

All three casts of the various Doris Days Shows (and her kids).

Cousin Pearl and Jethrene.

Darrin's best drinking buddy Dave.

Etta Candy, General Blankenship and Wonder Girl (Drusilla) after season 1 of Wonder Woman.

Yeoman Janice Rand on Star Trek.

Andy Taylor's GF Ellie.

Larry Mondello.

Dick Martin's character on The Lucy Show (and her kids).

Milton Armitage and Thalia Menninger on Dobie Gillis.

Cindy Lee on Isis.

Gordy on MTM.

John on Taxi.

Chuck on Happy Days (maybe it really IS about him).

That's some list.

For the Doris Day Show every season characters are dropped. Everyone from the first season are pretty much gone by season 4. After that, bosses change, side kicks change, apartment neighbors change. The only constant was Doris herself.

My Favorite Martian lost Mrs. Brown's daughters quickly in the first season.

On one of the early seasons of The Big Bang Theory, Leonard's girlfriend Stephanie. At that point, before Leonard and Penny became seriously involved Leonard was dating a young woman named Stephanie for a few episodes. She starts talking about wanting to move in and live together with Leonard, but Leonard is nervous and uncomfortable about the idea though. He tells her he doesn't want to live together and they have an argument about it. Which has Leonard later telling Howard and Sheldon I'm never dating or having sex again. At which point he gets a message on his cellphone from Stephanie, and he looks at it and then basically says Oh I guess I am, see you later at the end of the episode. One can assume they broke up though (but it's never said on camera) because after that Stephanie's never seen or even mentioned again.

Ed.

Saved by the Bell was notorious for this.

I think Roseanne/The Conners is also. Where's Crystal/Nancy?

Actually, pretty much any sitcom. It's more unusual for there to be any proper closure or sense.

ginny...on one day at a time.she was fun.......great personality....played by great actress !!!