Characters they "watered down"?

[AnthonyO'Brien]

Punchy. Didn't he used to beat his friend a lot?

Vengeful forties batman turned into smiling happy guardian for Robin

Who else?

[CaptainEurope]

Emma Frost. She used to kill horses to manipulate teenage mutants.

[AnthonyO'Brien]

Thanks. Lupin iii. Used to fool around with nekkid ladies kicking their bare behinds if they annoyed him. Now he does Japanese theme park rides and team up movies with detective Conan...

[Zauriel]

Deathstroke the Terminator was willing to endanger his son's welfare to protect his client's identity. He wouldn't sell out his clients to save his son. His honor cost his son's voice and nearly his life. Now he is a doting parent to his daughter, whose life he wouldn't risk for anyone including his clients .

[AnthonyO'Brien]

Andy Capp. Used to make jokes while beating his wife, giving her black eyes a number of times. The strip gradually watered this down and tried to find loop holes after obvious outrage. Beatings would later occur off panel or with the lights off, sometimes beating *someone else's* wife. Now it's mostly mother in law jokes and I don't think he even smokes anymore...

Logan and Fury no longer smoking...

[JackDaw]

Andy Capp. Used to make jokes while beating his wife, giving her black eyes a number of times. The strip gradually watered this down and tried to find loop holes after obvious outrage. Beatings would later occur off panel or with the lights off, sometimes beating *someone else's* wife. Now it's mostly mother in law jokes and I don't think he even smokes anymore...

Logan and Fury no longer smoking...

Andy Capp was a strip I regularly read back in the 70’s...he was always less than a role model (seeming to spend most of his life in local pub) but can’t remember him treating Flo so abysmally.

[Riv86672]

Godzilla went from being born of atomic fire and being unleashed upon an unsuspecting humanity as a metaphor for the horrors of nuclear destruction to an anthro-animal superhero who fought using kung fu moves and stayed out of human cities, only leaving his territory to defend us from invading aliens.

[ed2962]

Even though they quickly undid it, there were a couple of Spiderman comics from the 70's where Punisher was using "mercy" bullets ( rubber bullets) instead of live ammo.

[Spike-X]

Grant Morrison talks about Golden Age Superman's post-war "hostile makeover" in their book Supergods.

I love the character as he is now, but I sure wouldn't mind seeing him dangle the occasional domestic abuser by their ankle out of a high window, or trapping a corrupt mine owner and his worthless 1% friends in his own unsafe mine. But that would probably be too "woke" for today's snowflake readership who need a safe space from reading a book that actually has something to say.

[Mister Mets]

Disney adaptations come to mind.

Beyond that, Spike from Buffy the Vampire Slayer seems to be an example.

TVTropes has some lists on similar questions.
https://tvtropes.org/pmwiki/pmwiki.p...eRevolvingDoor

https://tvtropes.org/pmwiki/pmwiki.php/Main/ExBigBad

https://tvtropes.org/pmwiki/pmwiki.p...n/HeelFaceTurn

https://tvtropes.org/pmwiki/pmwiki.php/Main/ButtMonkey

https://tvtropes.org/pmwiki/pmwiki.p...armlessVillain