William: a demon King who kills for fin, sexually harasses to get his way, and ....an amazing singer :'3 the devil works for him

Weaver: BrO hE iS gAwD

Silhouette: Self-centered depressed Cannibal. Has a soft spot for his daughter, midnight (UwU)

Midnight Dreams: Soul Catcher. Wendigo. Bad news

Professor Peter Quinn GutSlit: A deranged mad Scientist who runs experiments on poor creatures

InkTrap: controls the shadow monsters and makes them invade silhouette

DeathTrap: an assassin who wants to get rid of The Afton's

I'll add more :)