- Draco Malfoy was introduced as a Jerkass Fantastic Racist rich kid who thought he was better than others because he was born in a rich family. As the story progressed he only showed more jerkassery as he openly declares that he wishes to know who the Slytherin's heir is so he could help him kill muggleborns, deliberately got himself harmed during a lesson so the teacher would be sacked (it didn't work, but the teacher's favourite hippogriff almost got killed for it), and so on. It culminated in the sixth book with several attempts on Dumbledore's life which almost got two other people killed.
- The Dursleys were also this for most of their series, where they had no qualms against neglecting and abusing Harry. But Dudley at least would mellow down as the series progressed, and Harry even developed a kind-of-friendly relationship with him.
- By the end of the series, two of the Dursleys have come to respect Harry. Petunia hated Harry due to unresolved jealousy at her sister and only friend Lily (Harry's mother), who left her behind to go to Hogwarts. Only at their possibly very last meeting does she for once feel any sort of bond towards him but never finds any way of expressing it. Dudley came to seriously respect him after he was saved from the Dementors, since it was basically an "I've treated him like crap for 13 years, and he still decides to save me anyway. My God, why did I ever treat him like that?" moment. This is helped by the Dementors who, instead of feeding on his bad memories (being a spoiled brat, he doesn't really have any), showed him just how much of an asshole he was and how empty his life would be if he didn't change.
- And then there is Marge Dursley. She's only really in one chapter of Prisoner of Azkaban, but that one was enough to make her the worst among the pack. She's a drunkard (who falsely accuses Harry's parents of having been the same) who cares more about her dogs than most people (which given how callously she has the runt of a litter drowned is very little as well), has very classist notions that put Vernon's to shame, shows joy at the thought of Harry receiving corporal punishment, and even Dudley has to be bribed to tolerate her presence. Ultimately, she gets her comeuppance from Harry, and due to special circumstancesnote and the fact that it was technically an accident, Harry isn't even punished for it!
- Gilderoy Lockhart may have been comedically incompetent at the beginning of Harry Potter and the Chamber of Secrets, but by the end was definitely this. He was a Know-Nothing Know-It-All characterised by extreme arrogance. He claimed to have performed many heroic deeds, but was actually a fraud who used the Memory Charm (the only spell he was even remotely good at) to erase the memories of others and claim the credit for himself. During his one-year stance as Defence Against The Dark Arts teacher, he was seen as a complete joke, not helped by his many attempts to one-up other Professors in their own field and failing miserably every time. What really propels him into Hate Sink territory, however, is that when real danger reared its head, he was revealed to be a complete coward who was willing to leave Ron's sister to her fate in the Chamber to save his own neck while attempting to wipe his and Harry's memories... only for Ron's wand to wonderfully backfire on him and wipe his own mind clean due to Ron's wand being damaged earlier in the story. It is worth mentioning that during his time as a student, his Professors noted that he was very intelligent (being sorted into Ravenclaw) and could have been a great wizard, but was so vain that he never actually bothered to develop his magical talents. Of course, three years later, a much, much worse Defence Against The Dark Arts teacher would arise, as mentioned below.
- Rita Skeeter, mostly during Goblet of Fire. She's a smug, obnoxious paparazzi journalist for the Daily Prophet, who has no respect for anyone's privacy, and spends the vast majority of her time writing blatantly false and slanderous articles that just serve to make Harry's (and Hermione's) life more difficult. Her writings about Harry convince Minister Fudge that Harry is crazy and shouldn't be believed about Voldemort, so she's more responsible for Voldemort's damage than one might think. She even manages to be just as scummy in the Deathly Hallows despite not personally appearing. There, she writes a tell-all book about Albus Dumbledore's life and darkest secrets, despite the fact that he was just recently murdered. She is, notably, the only person in the entire franchise that Dumbledore (including his younger self in Fantastic Beasts) treats with outright contempt instead of his usual condescending rudeness he uses on people he doesnt like.
- Fenrir Greyback, while not as widely hated as many of the above examples due to his villainy being of the same over-the-top and impersonal brand as Voldemort's, is still a cannibal and the werewolf personification of Would Hurt a Child, to the point of even being implied to be a pedophile.
- Dolores Umbridge lacks the charismatic traits of even Lord Voldemort, instead showing herself to be a self-centered, power-hungry, and bigoted figure, outclassing Lockhart as the most despicable Defence Against The Dark Arts teacher by far. In Harry Potter and the Order of the Phoenix, Umbridge demonstrates the consequences of giving power to a bigot, promoting hatred towards muggle-borns, depriving students of the capacity to learn self-defense, and disrespecting the inhabitants of the Forbidden Forest. In Harry Potter and the Deathly Hallows, she charges muggle-borns with stealing magic.
- Marvolo Gaunt is The Patriarch of the Gaunt family and one of the last living descendants of Salazar Slytherin alongside his children Morfin and Merope. Marvolo treated his daughter Merope with nothing but contempt, forcing her to do all the work and berating her for her lack of magic, a Self-Fulfilling Prophecy since abuse stifles the development of magic. Because of his bloodline, Marvolo thought he was untouchable, and proved to be unreasonable when confronted about his sons attack on a muggle named Tom Riddle. When Marvolo learned of his daughters infatuation with Riddle, he tried to strangle her in front of a Ministry official, leading to his and Morfins arrest. Marvolos abusive treatment of his daughter caused decades of suffering for the wizarding world when Merope despaired after being left by Riddle and died giving birth to his son, who would become Lord Voldemort and instigated two wars in a mad quest for power and immortality.
- Pansy Parkinson is portrayed as a one-dimensional Alpha Bitch who's rude, insulting, prejudiced, and cruel with no improvement throughout the series; she's also the only Hogwarts student who wants to sell out Harry to Voldemort in exchange for safety. On top of that, she's dumb and ugly. The author describes her as "...every girl who ever teased me at school ... I loathe her." and isn't particularly subtle about it.
- Peter Pettigrew, also known as Wormtail, is a former classmate-turned-nemesis of the Marauders having betrayed the Potter family to Lord Voldemort when his life was threatened. Initially presumed dead at Sirius Black's hands, Wormtail actually framed Black as Voldemort's informant before faking his own death, killing innocent people and removing a finger in the process before transforming into Ron Weasley's pet rat, Scabbers. When confronted by Lupin and Black, Wormtail blames Voldemort's threats for his treachery, before begging for his life. After escaping the encounter, Wormtail serves Lord Voldemort out of self-interest, eventually culminating in an attempt to kill Harry Potter despite the latter saving his life.
- Severus Snape is like this for the early part of the series, he was largely viewed as a cruel, bitter, and absurdly unfair Jerkass by readers. This changed somewhat in Book 5 when Umbridge replaced him as Hogwarts' resident Sadist Teacher, only to skyrocket right to the top of the fandom's hate list by the end of the following book for apparently murdering Dumbledore, before finishing out the series, with the shock reveal of just how much of a hero he was all along, despite remaining a cruel, bitter and absurdly unfair Sadist Teacher.
- Vincent Crabbe and Gregory Goyle, Draco's two handymen, are essentially Mr. Malfoy minus even the microscopic redeeming qualities that Draco himself possessed, or any kind of explanation for their actions beyond being obnoxious, brutish bullies. Having the same personality as Draco but being even dumber, uglier, and crueler, no one was remotely sorry when Crabbe (Goyle in the movie) got himself killed in an unbelievably stupid way by his own misdirected spell in an attempt to kill Harry, Ron, and Hermione, making him the only person in the series dumb enough to die in the Room of Requirement.
Hate Sink / Harry Potter