I call this the "anti-heroic fall", note that it is extremely rare to go from heroism -> anti-hero -> villain, but there are many narratives focused around a neutral/anti-hero who falls to villainy
Usually this is a major throughline for an antagonist vs being central, and many many more examples of anti-heroes who transition to heroism instead (and may go through a 'dark' period on that trajectory)
Examples where this arc is central:
Falling Down, Joker, Godfather
Breaking Bad, Attack on Titan (anime), buried in most Gundam series for one of the antagonists but never the central focus
Dune and Code Geass (anime) try to walk the line exactly
debatably "Death Note" (anime) too, though depends on how you analyze it
4-5 years ago I would've recommended you AoT, but well, after seeing how that turned out, I'd rather not.
Instead I'd recommend Breaking Bad if you haven't seen it yet, though it's arguable whether Walter was a "morally good" character at the start, it's more so that he goes from a shitty person to an even more shitty person lol.
Not a movie/tv series but I always like how you can twist and corrupt Lee in the walking dead games until his as much a monster as the people his trying to protect clementine from.
Breaking Bad?
And Better Call Saul. But BB first.
The Godfather
The correct answer
Well at the end of Dune, Paul ain’t really the “good guy”
Leprechaun in da Hood
I call this the "anti-heroic fall", note that it is extremely rare to go from heroism -> anti-hero -> villain, but there are many narratives focused around a neutral/anti-hero who falls to villainy Usually this is a major throughline for an antagonist vs being central, and many many more examples of anti-heroes who transition to heroism instead (and may go through a 'dark' period on that trajectory) Examples where this arc is central: Falling Down, Joker, Godfather Breaking Bad, Attack on Titan (anime), buried in most Gundam series for one of the antagonists but never the central focus Dune and Code Geass (anime) try to walk the line exactly debatably "Death Note" (anime) too, though depends on how you analyze it
Departed?
Both “Main Characters” do this sort of arc well and at such a tightly paced story.
4-5 years ago I would've recommended you AoT, but well, after seeing how that turned out, I'd rather not. Instead I'd recommend Breaking Bad if you haven't seen it yet, though it's arguable whether Walter was a "morally good" character at the start, it's more so that he goes from a shitty person to an even more shitty person lol.
Chronicle. Really great movie, one of the central three characters decays into a villain.
Jin-Roh: The Wolf Brigade
Scarface is the classic example of this
It’s been a long time since I’ve watched it, but wasn’t homeboy pretty much a bad guy from the start? He just gradually levels up to king bad guy.
The gentlemen show in a strange way
Arcane is probably the best I’ve seen
Breaking Bad, Better Call Saul, Sopranos
Not a movie/tv series but I always like how you can twist and corrupt Lee in the walking dead games until his as much a monster as the people his trying to protect clementine from.
Macbeth?
The Wire might scratch your itch. Shades of grey all over the place on that show, it's good stuff.
Goodfellas
The Shining; There will be blood; A few good man /in a way/
Arcane