History TookALevelInJerkass / WesternAnimation

* Charmcaster in ''WesternAnimation/{{Ben 10}}'' used to treat her golems (or whatever they were) like they were pets. In ''WesternAnimation/Ben10AlienForce'', she can't go a few minutes without insulting the giant ones she has now for everything they do. Also, in the original series, while a troublemaking bitch, she wasn't murderous or out to take over the world. In ''Alien Force'', she does try to conquer the world, and expresses a gleeful desire to kill Gwen.

** And let's not forget about Gwen, who, during the first seasons of ''Alien Force'', was portrayed as a more calm and responsible person who was less of a DeadpanSnarker, but sometimes prone to {{Tsundere}} outbursts. By the third season, she is now back to her old [[DeadpanSnarker snarky]] and [[HairTriggerTemper short-tempered]] self who laughed at Ben after pouring a smoothie at him.
* And Julie as a result of becoming an example of DerailingLoveInterests in ''Ultimate Alien''.

** And let's not forget about Gwen, who, during the first seasons of ''Alien Force'', was portrayed as a more calm and responsible person who treated Ben nicely and sometimes prone to {{Tsundere}} outbursts. By the third season, she is now back to her old [[DeadpanSnarker snarky]] and [[HairTriggerTemper short-tempered]] self who laughed at Ben after pouring a smoothie at him.

* Pietro Maximoff on ''{{WesternAnimation/X-Men Evolution}}'' started as a minor antagonist/rival with some JerkAss traits; when season two hit, he was the only one who doesn't become sympathetic & by the end of the series he takes a level in Jerkass by revealing that Mystique had been impersonating the Professor so she could blow up the mansion, something Pietro and the other Brotherhood members not only knew, but likely helped. Then he fucks EVERYONE over by joining the Acolytes, Magneto's new team, since he had been TheMole the whole time. Then when Magneto lets the Brotherhood join him he puts Pietro in charge, who has Toad work as a ''TV antenna'', and Blob make him sandwiches, throwing them back in his face for the tiniest detail until Blob ''cries''.

** And let's not forget about Gwen, who, during the first seasons of ''Alien Force'', was portrayed as a much calmer and nicer person who treated Ben nicely and sometimes prone to {{Tsundere}} outbursts. By the third season, she is now back to.

* Sokka from ''AvatarTheLastAirbender'' temporarily went through this in ''Bato Of The Water Tribe'' when he yells at Aang for hiding his father's map. Though this is partly justified; Aang DID act dishonestly in hiding the map from him and Katara. Still...that was harsh.

** Throughout most of his Season Fifteen appearances for that matter, Mr. Mackey has started to reveal more and more darker personal issues, albeit ones he frequently vents out on the school's students. His hoarding problem led him to be violently protective of his belongings, while he and the school faculty became so obsessed with avoiding controversy over school deaths they decided to [[RefugeInAudacity kill Eric Cartman by]] [[ItMakesSenseInContext throwing in under a bus]].

* Poor Marty McFly. As if it weren't enough for the [[BacktotheFutureTheAnimatedSeries animated series]] to take his competence and intelligence, it had to do this as well.

** Joe Swanson took several levels of jerkassery once he regained the ability to walk in the episode "Believe it or Not, Joe's Walking on Air". Joe gained confidence in himself once he could walk again, but it got to the point where he demanded his not-so-physically-fit friends to keep up with him in his extreme physical activities and insulted them for not being as good as he is. It got to the point where Joe ditched his friends for new ones and dumped Bonnie while she was still pregnant. Joe had to be recrippled in order to get him back down to humbleness.

** Icky Vicky: Originally just a mean, bossy babysitter. Now a sadistic, maniacal human monster not above threatening her own parents to keep her [[BeneathTheMask true colors]] a secret.

** Milhouse definitely took a level in this, to the point that he ruined Bart's relationship with the GirlOfTheWeek simply because Bart didn't visit him. He also tried to manipulate Lisa during the ending of The Simpsons Movie by saying Colin was dead and his last words were for Milhouse to take care of Lisa and hold his hand.

*** Much of Galvatron's JerkAss traits come from being left in a plasma bath that affected his neural circuitry, following [[TransformersTheMovie his defeat at the hands of]] [[TheChosenOne Rodimus Prime]]. He spends more of his time being a BadBoss, beating up on his own troops, than he does blasting Autobots, to the point where in "Webworld" Cyclonus - his most loyal lieutenant - gets tired enough of the abuse that he tries to have Galvatron "cured" of his insanity. [[{{Understatement}} It doesn't work.]]

* A large amount of the cast of ''WesternAnimation/TheSimpsons'' have evolved this way as the show has leaned into zanier, more satirical, territory. The most infamous case of this occurred with Homer Simpson: While he was always selfish and moronic, he initially had some level of goofiness and kindness to offset this. When Mike Scully took over (in season 9) and shifted the show into more of an overt comedy, his selfishness and sociopathy went to [[Series/StarTrekTheNextGeneration Q-esque levels]], to the point where he almost became a full-blown VillainProtagonist. When Al Jean took over, he toned down the character, so now he floats between his early era goofiness and his infamous Scully-Era persona.

** Randy Marsh started off as a somewhat incompetent but well meaning parent, and to an extent one of the more rational adult residents. As his role elevated, he slowly evolved into a sociopathic AdultChild whose selfish antics his family often have to face the brunt of (especially his son Stan).