The current chapter highlights the essential roles of masks and makeup in both classical modern and contemporary horror films such as Texas Chain Saw Massacre, Halloween, Friday 13, It, Terrifier, and other less commercially successful works such as Killer Klowns from Outer Space (1988) and In a Violent Nature (2024). Overall, two main patterns are explored: the psychopathic but human mask-wearing serial killers, and the demonic, non-human but clown-like, and thus partly human-like, killers in Killer Klowns from Outer Space, It, and Terrifier. The analysis suggests that masks can be frightening, regardless of a human or a non-human creature wearing them. Paradoxically, demonic killer clowns from other realms do also incorporate comical features.