Devilman/Nightmare Fuel
< Devilman
This series is one of the earliest horror manga out there. As such, it manages to have quite a bit of horrifying imagery throughout its run. But for some specific examples...
- Jinmen. Check out Tear Jerker for what he's done, but the sheer glee in which he takes from it, the taunting, the way he defends himself from Devilman...it's simply horrifying.
- the faces of those he's eaten appear on his shell, still alive, and still conscious until he's done digesting them.
- When an Angry Mob descends on the Misimaru's home...and tear both Miki and Tare limb from limb (Tare first, in front of Miki) cements the idea that as evil as the demons are, Humans are Worse.
- A spider-demon burrowing out a girl's face. It had controller her mind and over time, ate it away completely, burrowing into her head until the body began to slowly rot.
- Amon devouring a child in Amon: Apocalypse of Devilman. Note, this is Akira in a Despair Event Horizon/ Heroic BSOD after witnessing the brutal aftermath of Miki's murder.