Shows where a beloved character slowly becomes the main antagonist/villain of the story?
As the title says, I really wanna find shows where a character thats really loved by audience/main character slowly goes through stuff and becomes the antagonist of the story. I dont think this counts as a spoiler since everybody who knows superman knows lex luthor, I really like how in smallville lex starts out as an actual likeable character and its genuinely heartbreaking to see him go through his development that inevitably turns him into a villain. Its even more impactful imo because as the audience, we know he needs to turn evil at some point since hes THE bad guy in superman. I also really enjoyed how his decent was well-written and took multiple seasons with instances of a possible redemption that ultimately failed. Thats the type of stuff i want and i am completely okay with any spoiler you guys would be giving by suggesting a show. Sometimes knowing a big plot twist is coming makes it more exciting to watch the story unfold and build up to that point. I am open to all suggestions!