- Bookiepop Phantom
- Ergo Proxy
- Higurashi
- Haibane Renmei
- Shiki
- Talentless Nana
- Speed Grapher
- Shinsekai Yori
- Chainsaw Man
- Terror in Resonance
- Elfen Lied
- Psycho-Pass
- Now and Then, Here and There
- Made in Abyss
- Paranoia Agent
- Monster
- Texhnolyze
- Berserk
- Devilman Crybaby
- Evangelion
List feels kind of… tame? I cant think of much off the top of my head but I’m pretty sure I’ve seen darker stuff.
Parasyte: The Maxim is fairly dark, and parts of the overarching story of One Piece are crimes against humanity.