Fan Casting He Who Fights Monsters in Sort by Tropes

"He who fights monsters should see to it that he himself does not become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." He Who Fights Monsters is not quite a villain, but they act antagonistically enough that they're little better than a villain. He may have good intentions; he might have a point when he says that the fiend is too dangerous to be kept alive. Other characters within the work itself might even concede that point. But ultimately, his obsession with dealing out due punishment (or worse) and his refusal to think about what he's doing twists him into a monster just as bad as, or even worse than, the one he's hunting.