Actors/characters that left TV shows too soon

It can be due to failing health, conflict on set (which in turn can lead to the actor getting fired) or just feeling fatigued with the character... Whatever the reason is, are there instances where you wish you got to see more before the character and/or actor suddenly were out of the picture?

Im watching Night Court right now. Really funny show, but has some of the most frequent cast changes you'll see in a sitcom. I'm only 5 episodes in, but I'm gonna miss Karen Austin as Lana Wagner. She has a very nice natural chemistry with Harry Anderson, and Lana is a little authoritarian, yet also has a sweetness to her. She is neither a tough cookie nor a cute little pixie.
And yet, she didn't even last for the entire season. Why?

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I remember late nights In Florida watching Night Court stretched out on the couch while everyone else was asleep.
Loved that show.

You just made me imagine Judge Harry Stone kicking back and stretching himself out over the couch right now.

Harry Anderson was a very gifted performer.

I wish Suzanne Somers had stayed with Three's Company. She left the show during the 5th season.

According to some Google sleuthing she developed Bell's Palsy from stress and was let go from the series because of that.

I was sad to see Denise Crosby leave Star Trek so soon, because having a female security officer (and also a female character not in a catsuit) was pretty cool. I love Worf, but losing Tasha Yar was a real shame.

I was also sorry to see the main actress from Sleepy Hollow leave. She had a great presence and good chemistry with all of the other actors. The show was going downhill and she bailed and I can't blame her, but her absence is like a black hole. I've been struggling to get through the episodes without her. I'm a completist, so I do want to finish the series, but MAN! Without her banter it's just not the same.

I wasn't upset when Tasha Yar left Star Trek: TNG, but I was sad to see Dr. Beverly Crusher (Gates McFadden) leave after the first season. I hated her replacement, Dr. Pulaski (Diana Muldaur), so I was very happy when Dr. Crusher returned in season 3.

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If I answer a game thread correctly, just skip my turn and continue with the game.
OPEN FLOOR.

Happy Days fell apart with the departure of Ron Howard...he was the heart of that show and it didn't work without him.

Also, David Caruso's swelled head caused him to leave NYPD Blue prematurely.