The old man in Ranma 1/2 is absolutely disgusting. Ranma 1/2 is an entertaining series otherwise, but the old man really ruins it. He's the pervert trope (which I'm happy to see I'm not alone in hating) combined with being an untouchable "master" figure which means he's never ever held accountable for his awfulness, and literally, he's not just a pervert, but he goes after teenage girls! 😨
Mineta from MHA is also bad. The other characters do punish him, but at the same time he never changes. It's not funny.
Another one I want to mention is the main character (Meliodas? It's been years since I went through that awful show) of Seven Deadly Sins. This is a particularly awful case that made me straight-up drop the series forever. The writer of this series just loves making the main character grope the female lead all of the time, and it's really gross. One of the - if not THE - first times, he gropes her while she's unconscious. I don't know how I got through one season of the show. It's so bad.