White-Haired God of Slaughter

(Decisive and ruthless + no saintly moral posturing + cold-blooded and merciless + brutal methods + cuts ties even with family)

From a frail invalid to the founding emperor, all it takes is a grand prize package of having his whole family wiped out.

From endless slaughter between humans and demons to peace between the two races, all it takes is billions of human and demon corpses to lay the foundation.

His wife despises him, his children hate him, and both humans and demons reject him? So what? Anyone who stands in his way must die.