Oh boy, The Owl House has some of the most loathsome and hated characters to ever enter the Boiling Isles for their evil actions, and also, TOH fans will most likely hate them because of this (Emperor Belos/Philip Wittebane doesn’t count and fits more in the trope Love to Hate):
- Mattholomule is quite the Jerkass in his introduction. He fakes human "artifacts" as a means of usurping Gus from his position as the club president of the Human Appreciation Society, even going as far as to send Luz and Gus to detention when the school is notified of Luz's presence. And to make matters worse, he actually succeeds in his plan when Gus steps down. However, this is subverted in the following season, as he turns out to have only been mean out of peer pressure from Glandus, has a change of heart, and befriends Gus, while saving him from a trio of evil Glandus kids.
- Bria is the most detestable of the Glandus trio, only caring about power and control, in contrast to Gavin (who wants to impress his father) and Angmar (who wants to make a butterfly sanctuary). When her kind and pleasant mask slips, she acts like an absolute jerk to Gus and sees her teammates as expendable, claiming she never liked them anyways.
- Odalia Blight is a mean-spirited and manipulative socialite who cares more for power, wealth, and reputation than the happiness of her children. While both she and her husband have Social Darwinist tendencies, Odalia is the primary disciplinarian while Alador has little interest in anything aside from his studies. "Clouds on the Horizon" has her reveal that she knew all along that Belos plans on wiping out life on the Boiling Isles with the Day of Unity. But Odalia kept it a secret because she believes her family will be spared and made into royalty as a reward for their service, all while acting smug and self-righteous about it. This is too much even for Alador who sides with their children, destroys their factory, and "quits" his and his wife's partnership. She also disapproves of Amity's relationship with Luz, telling Amity that they'll find her a more appropriate girlfriend once Luz is arrested, which causes Amity to disown her mother and vow to never speak to her again. All of this is done with the intention of making Odalia into a character that the audience would want to see fail.
- Kikimora. Cowardly? Check. Sleazy? Check. Arrogant? Check. Self-righteous? Check. Petty? Check. A backstabber who's perfectly willing to kill a child whether they're on her side or not? Check. Being aware of what the Day of Unity will actually entail and not caring one bit about others for her own gain out of a deluded belief that Belos would spare her? Check. From all of the aforementioned negative traits Kikimora has, it is safe to say we're not supposed to enjoy her screen time. After other villains get more positive traits or outright defect in Season 2 she comes to share this role with Odalia, who not only willingly allows the Emperor's genocide to happen, but thinks her family's social status will be elevated in exchange for her loyalty. Kikimora on the other hand is fairly humbler in her desires and thinking by comparison. She seems open to the possibility she will die in the process, but she'll take satisfaction knowing she'll stick it to Hunter before the Day of Unity happens, and she thinks she’ll be rewarded and enjoy it before she dies.
- Of all the Coven Heads seen so far, Terra Snapdragon easily has the least redeeming qualities to her. She loves to toy with her own allies and generally doesn't care about the lives of others (even children), actually showing disappointment to announce she wouldn't get to kill Kikimora. And that's not even getting into her attempts to brainwash and modify Raine's memories to keep them under control, only failing to do so because they wised up to her scheme and pretended to be under her thrall.
- Arguably moreso than Terra, who at least had some legitimate Pet the Dog moments in preventing Eda's expulsion and Bump's firing from Hexside. By contrast, Adrian Graye is an Attention Whore with little respect for anyone but himself: he treats his subordinates like dirt when they can't follow his extremely vague directions, he tries to permanently lock Gus into the Abomination Coven out of spite for Gus thwarting his plan to brand the students at Hexside, and he's perfectly willing to desecrate the graves of fellow Illusionists so that he can bring Belos a Galdorstone and be rewarded for it. Furthermore, while he is a legitimate threat, he is much more of a Smug Snake compared to Terra, relying on an Amplifier Artifact to boost his magical abilities and otherwise being largely outclassed by Gus, a child.
- While they never appear directly, from what we do know about them, the Archivists were a group of genocidal Jerkass Gods who abandoned their sibling and wiped out the Titans, in the process causing pretty much every tragedy in the series.
- The Titan Hunters, who are so fanatically driven to finish their genocide against the Titans that they have no qualms about posing as Titans themselves to lure in their quarry—especially those Titans too naïve to see the holes in their story. The simple knowledge that King exists is enough to make Bill and Tarak launch a plot to lure him to the opposite side of the globe just to try to sacrifice him to the Collector, who they’ve alienated with their fanaticism and bloodlust, as he’s reminded of his aforementioned siblings. Even after getting to know King personally and being able to see that he’s harmless unless provoked, the tribe attempts to go ahead with their plan immediately, which if successful would have rendered the Titans extinct due to King’s endling status. Nor does it seem to bother them that King is only about eight, as Word of God confirms that they killed the rest of King’s siblings before they could hatch and that the skulls the hunters wear are all those of other Titan children they’ve killed, as a full-grown Titan’s skull would be impossible to wear. It may also be noted that the Titan Hunters, despite showing no ill-will towards Hooty, are made up entirely of witches with demons conspicuously absent on their island; as the demons are literally born from the corpses of Titans, and display a godlike reverence for them (at least on the Boiling Isles, where this reverence also is displayed by witches), the local demons may have left in fear of being persecuted as Titan worshipers, or could have been the victims of a genocide themselves.
