Probably the most extreme example out of this page, JerkassAmoral AttorneySteve Dallas gets kidnapped by aliens and Brainwashed into a touchy-feely, effeminate hippie. Ironic, because this is also one of the best cases of Tropes Are Not Bad. Avoiding Snapback and We Want Our Jerk Back typically associated with this trope for several years, Steve Dallas becomes a much more sympathetic character and even patches up his relationship with his mother during this time period.
This character also a rare case of this trope being subverted. Steve ended up being too annoying, and Hodge-Podge did start to want the original Steve back, so he ended up back to his old self.
Also another example of Tropes Are Not Bad, Opus was derailed from a generic Funny Animal to the neurotic, politics obsessed, couch potato materialist we all know and love today.
This happens again in Bloom County with Bill the Cat. For most of the comic, when he wasn't in a drug-induced coma or brain dead, he did nothing but spout gibberish. Toward the end of the comic's run, he was kidnapped and had Donald Trump's brain transplanted into him.
The dad in The Family Circus was originally a lot more buffoonish◊, and used to be more devious — such as sneaking his own booze into a sporting event, banging on the table when Thel tries talking to him, et cetera. By the 1970s he was a lot trimmer◊ and wore glasses, and his personality became a lot more sympathetic. His is yet another example of Tropes Are Not Bad.
Not too many people know that the U.S. Acres segments on Garfield and Friends were based on a comic strip of the same name, also created by Garfield creator Jim Davis. In any event, there weren't too many changes from the US Acres strip to the animated version... except in two characters: Bo Sheep went from The Ditz to a somewhat normal-intelligence Surfer Dude; and Sheldon lost his introspective, meditating edge to become basically a one-note character whose main joke was that his shell was a Clown Car Base. To a lesser extent, Bo's sister Lanolin was tamed in the transition.
There's some people who like comic book Bo and other people who like cartoon Bo better because some people feel Cartoon Bo was given more depth from a one note ditz to a Genius Ditz. Some people also actually like cartoon Lanolin and felt she was given more depth then just a one note Jerkass. And there WERE a lot of changes from the strip to the cartoon. While Sheldon may not have changed for the better, others did. Orson, Roy and Wade were given more depth in the cartoon version. Cartoon Orson's less of an annoying idiot, Cartoon Roy went from a one note jerkass to more of a Jerk with a Heart of Gold, and Wade improved the most. He went from a pointless Chew Toy which was unbearable to read in the strips, to a (non Chew Toy) wacky funny Lovable Coward. The biggest change (for the better) was Roy and Wade's friendship. In the comic version, Wade didn't stand up for himself much towards Roy but in the cartoon version, Wade retaliated to Roy to the point where arguing with Roy was usually the possible only thing Wade wasn't afraid of! Roy and Wade also became much more Vitriolic Best Buds and closer friends as later seasons went on.