Yeah, and they moved in next to the Left-Handed Man.
How about Kerry Weaver on e.r.? At first she was a raging bitch. Then she was a raging bitch some more. And then she was still a bitch. Then, suddenly human, though gruff. Then human with the occasional gruff or bitchy moment.
Didn’t she become a vagitarian somewhere in there, too?
While discussing the trendy “secret lesbian” (or newly bisexual) plotline that runs through so many series lately, my mom claims that Kerry dated men first too, so maybe she did become a lesbian. I don’t recall her seeming to prefer men, though, so I’ll leave the debate about if that was a tranformation to people with better memories.
The was a quick scene in one of her early episodes where an African man showed up and it seemed that had been or still were lovers. Probably her first scene where she wasn’t a raging bitch. I don’t think that guy showed up again. The writers were probably still trying to figure out which characters should have an interracial romance.
In the first episode of ‘Green Acres’, Lisa Douglas (Eva Gabor) was a sneering, sharp-tongued bitch, who made no secret of how much she hated being shanghai-ed from Manhattan luxury to the sticks. But she soon softened up into sweet, goofy eye candy - it almost seemed like Hooterville had instantly, mystically dumbed her down.
The first one I thought of when I saw the thread title was Ryan on ‘The Office’.
Sheriff Andy Taylor of "“The Andy Griffith Show” went from a fun loving, guitar playing, wise cracking character with a knack for storytelling to a serious, short tempered man who was constantly riled by Goober’s latest stupid blunder.
Didn’t Kerry date Clancy Brown’s character on a multi-story arc? He was an administrator or something…
And the Luke & Laura thing on General Hospital is what I came in to post. I thought it was creepy in junior high school that she fell in love with the guy who raped her on the floor of the disco, and they became the standard for Soap Opera Super Couple.
They did revisit it, though, decades later, as Lucky and whoever his half-brother was got into a fistfight over whats-his-name telling Lucky that his dad was a rapist.
Even worse was Sheriff Lobo (from BJ and the Bear). He was introduced in a two-hour movie (I think there were a couple of them before BJ became a series) as a Sheriff who arrested women and forced them into white slavery. BJ was hired to get the women out of the county in his truck, and Lobo did everything he could to kill him. BJ won, of course, because he had a chimp on his side.
When they spun Lobo off into his own series, he was suddenly a heroic, fish-out-water Lawman (sort of like a comic version of McCloud).
Now, anyone who actually knows what I’m talking about has an idea how freaking old I am!
Just checking in to say that I would be absolutely 100% hunky-dory OK with that as my fate.
But he recovered in time to become a wise old defense attorney with a lot of white suits! 
They lampshaded that when Susan Lewis came back to the series after several seasons away. Practically the entire staff had turned over since Susan had left, but she does a double-take when she sees Kerry. Paraphrase from memory:
Susan: “She’s still here?”
Jerry: “Worse. She’s in charge.”
When I read that, I laughed so loud I scared my cats. 
Never heard that term before.
She was supposedly in the closet and in denial up until Kim Legaspi seduced her in S7.
Best fanfic covering the Ripper/Ethan relationship I’ve ever read: House of Women by nwhepcat. Post-Chosen, the earlier stories in that series went AU sometime during Angel 5th season (Wesley comes back as a Watcher rather than continuing to work for Angel at W&H).
*** Ponder
True dat… he went from Sheriff Friendly Cornpone in the first few episodes to eventually the usually pissed off town daddy trying to keep his idiot deputy and the idiot townsfolk out of trouble. By the time the series ended he was a pretty hardcore guy when crossed. You had no trouble imagining he’d take a belt to Opey if he felt the situation called for it or kill a bad guy.
It was that damn Warren Ferguson!
This was addressed on the show, although I think it was hinted that she became a more unpleasant person because she spent so much time with Jerry, George, and Kramer. In earlier seasons Elaine was depicted as having a number of female friends. She has a baby shower for one, she is the “best man” at a lesbian wedding, and is having some sort of get-together at her apartment when Jerry gives her the cigar store Indian. As time goes by she seems to become increasingly outspoken and judgmental, although at least initially this is based on her political/moral beliefs (like being pro-choice).
By season seven she says she has no female friends left and tries to befriend Susan. She does have some female friends the next season, but they don’t seem to be close and she manages to alienate them through her hatred of The English Patient. Also in season eight she begins dating the “Bizarro Jerry” and tries to join his kind, considerate, and intellectual bunch of friends, but things don’t work out because she’s too aggressive and has rude mannerisms (like eating from the fridge without asking) that she’s picked up from spending too much time around Jerry & Co. In the end, Jerry, George, and Kramer seem to be the only close friends she has left.
Oh, I confirmed my memory of these episodes using a website I just discovered, Seinfeld Scripts. It has both summaries and complete scripts for Seinfeld episodes. Fun stuff.
The most extreme and sudden example of character change has to be Homer Simpson in Police Cops. The producers changed him overnight from a can-do action guy to a boneheaded klutz.
I seem to recall there was some guy with the same name who had to change it because his buddies ribbed him so mercilessly.
I thought Ross in Friends deteriorated badly as the show went on. He started out as a professor of anthropology, witty if a bit on the nebbish side. He ended up being a whiny neurotic loser. Whether that was a natural evolution of his three divorces or lazy writing, I don’t know.
The final straw for me with hiim was when he and Rachel got married in Vegas under the influence and the next day Rachel said “It’s fine, we can just get an annulment”. Ross pulls this goofy grin and says “But, I can’t be a man who’s been divorced three times”. I mean seriously, what the fuck?
Agreed re: Ross. You can date a random Friends episode simply by watching Ross for five seconds. If he is a plausible human being, it’s season 5 or before. This corresponds pretty closely with the entire show becoming but a pale shadow of its former glory.
IIRC, Kerry Weaver (e.r.)did have a brief (consummated) heterosexual affair with someone who was doing business with the hospital (selling medical supplies or something). I *think *it ended because he expected preferential treatment in their professional relationship. Anyway, she’s a good example of a big personality change.
The best one mentioned so far, I think, is Mark from **Roseanne **-- not because he got dumber (he did, but it wasn’t a qualitative change), but because he started out as an evil biker scumbag and turned into a dim but devoted husband and a hard worker.
Homer Simpson didn’t just get dumber, he became completely psychotic. I miss the Homer Simpson who lived on planet Earth.
Ooh, good one: Bubbles on The Wire.