Star Butterfly may be the hero of the series, but she has a lot of actions that paint her in a much less sympathetic light. She often acts impulsively without thinking about others, is prone to running away from her problems instead of trying to fix them, suffers little to no consequences for her actions, has rather self-centered behavior in regards to dealing with romantic interests like Marco and Tom even after her character development in season 3, and shows a lot of blatant hypocrisy in season 4 by expecting others to trust her, yet doesn't have the decency to trust others, and also by scolding others for exhibiting flaws that she is still shown to have. It gets even worse in the series finale, "Cleaved", where she commits magical genocide and yet suffers virtually no consequences whatsoever.
Glossaryk can also be considered this. He's intended to be a neutral character with a sense of mysticism, yet he's never clear with his intentions, and shows no regret/remorse when he shows tough love with those he's helping, showing a very smug snideness. His scenes where he feels unappreciated for his efforts makes him look like an Ungrateful Bastard.
Pony Head really falls into this. In her first appearance, she tried murdering Marco out of petty jealousy. Subsequent episodes try showing more of her humanity, but with how narcissistic and egotistical she is, she looks like a near psychopath. Not helping things, is how she's severely underdeveloped.
Starting in season 3, Marco Diaz is this for much of the same reasons as Star. His more jerkish, stubborn, and standoffish behavior is simply meant to be him being too confident in himself, but he's so smug and narcisistic about it that he comes across as cold and selfish, and he's never properly called out for it.
Solaria herself comes across as this in the finale. Her disowning Mina by turning away as she's crying out for her help comes across as cruel and hypocritical on her part especially since she chose and created what eventually became Mina's current state downright to causing her to lose her mind! Supplementary books like the Magic Book of Spells where her entire entry on monsters consists of racist ramblings and creative ways to destroy monsters on the pretense that they are "much happier that way" don't exactly help either and only make her sudden Heel–Face Turn come out of nowhere and rejecting Mina less heroic and more of a Kick the Dog moment.
