The Beast from Beauty and the Beast only spent the first half of the film as a jerk but after warming up to Belle, he goes from a jerk with a temper to a Jerk with a Heart of Gold. Despite this, people who believe in the infamous Stockholm Syndrome theory will often use this to justify why they think it's Stockholm Syndrome.
Cinderella still carries the stigma of needing a Fairy Godmother and Prince Charming to whisk her away to her Happily Ever After. While that is how she got her Happy Ending, critics often accused her of waiting and counting on someone to lift her out of her dire straits from the get-go. The truth is that the idea never crossed her mind, and she didn't even know the man she met at the ball was a prince until long afterwards. This accusation was so pervasive that several Disney movies, such as Frozen, The Princess and the Frog, Enchanted, the original film's sequel, and even as far back as The Little Mermaid, all put some thought towards averting or deconstructing the notion of a passive princess who needs another to grant her heart's desire to her with no actual effort on her part.
The Little Mermaid got flak for Ariel striking her Deal with the Devil to allegedly chase her crush with the human prince, ignoring the fact she harbored a passion for the human world from the very beginning and, if anything, it was the actions of her Fantasy-Forbidding Father that pushed her over the edge, which incidentally, Triton himself tends not to live down.
Ironically, Ariel in the sequel isn't likely to live down her tactless Parental Hypocrisy. Then again, a crazy sea witch searching for your only child can do that to you. Viewers also tend to forget that Ariel and Eric state that they were eventually planning to tell Melody everything, and were just waiting until she was old enough to handle it; the night Melody ran away isthe same night they decided that it was time.
For Big Hero 6, even though Hiro Hamada is a mostly nice kid, the fandom will warp his attempt to kill Professor Callaghan to sociopathic levels, even ignoring the part where he realizes his mistake and the aspect of Callaghan inadvertently killing Tadashi.
From Chicken Little, Buck will never live down being a neglectful parent towards his son and more or less not treating him very well, with people even suggesting he likes neglecting Chicken Little and making him seem like the villain. Despite the fact that he does genuinely love his son and shows signs of improvement later on, it was considered too little and too late and therefore he will forever be known by Disney fans as one of the most problematic parental figures in the Disney canon.
Kiara in The Lion King II: Simba's Pride is known by fans for being a horrible hunter. She fails one hunt, and it's the first hunt she's ever done, not helped by the fact that Timon and Pumbaa were tailing her.
Non-Disney
My Little Pony: Equestria Girls: The relation between Twilight and Flash extends to just a crush and nothing more. However, the fans bash upon Flash Sentry like he did more than just that and gave him the title of "Waifu Thief".
Sunset's plan of physically cutting and pasting photographs to frame Twilight is another one, for just how awful and poorly thought out it is, yet somehow nearly convincing the principal of the school. Even despite showing herself to be more intelligent later on, it left a stain on Sunset's reputation for a while.
Sonata talks about tacos exactly once in the film. From the fanfics, you'd think it's her Trademark Favorite Food. It's a memorable and hilarious line, and she says it with a borderline Squee, but still, one time.
Additionally, Sonata only says "For realzies?" once in the entire film, as her first line. Yet, fans treat it like it's her Catchphrase that she says almost every other sentence.
The Rugrats Movie: Many people consider Tommy practically psychopathic for nearly pouring banana baby food on Dil and leaving him in the rain to be taken by the monkeys, even though he quickly becomes remorseful and embraces Dil when he starts crying. It doesn't help that some people state Tommy wanted to murder Dil, even though it's never even implied the monkeys would kill him to get the food.
Peaches's characterization as an obnoxious teenager that's basically a copy and paste of any teen sitcom cliches is the characterization she's mostly remembered for. This is despite the following movie and the Easter Special gave her a more mature personality and was shown to even be a much nicer person than the way she was in this movie. Granted it doesn't help that the parts of the franchise where she's portrayed more positively are the ones the fandom prefers to ignore.
Sid is far from the sharpest tool in the sheed but his detractors tend to point to the scene where he ignores Diego's warning and eats the lotus berry and gets paralized as a proof he's the most useless character ever often ignoring all the other times he has being helpful to the Herd or the fact he didn't do anything as idiotic as this before this movie.