Utilising the complex mechanics of monstrosity and horror in The Pillowman by Martin McDonagh, this chapter places a marker on it as one of the pillars of this current tradition in British Gothic literature. The analysis first establishes a theoretical foundation, drawing upon Gothic theory and monster studies to situate the play's distinctive aesthetic, which has been critically described as a grotesque and inhumane cartoon-heightened style. It therewith proceeds to anatomize the main monstrous characters of the play, not just to one archetype, but to evil itself on a scale. This is the monster-perpetrator of the form of the child-like murderer Michal; the monster-authority of the form of the brutally self-righteous detectives Ariel and Tupolski; and the monster-parent, the bearer of a primordial, market-based brutalities. In the case of each, the analysis investigates what they desire and the particular mechanisms of production of terror, psychological, physical, and systemic. There is a fundamental inquiry into the most innovative horror in the play, the metafictional. In this case, the very process of telling the story turns into a monstrosity because narratives mix too dangerously with reality and serve as templates of violence. The chapter finally concludes that the vicious circle of abuse illustrated in the play is the greatest horror therein since monstrosity is not a condition but a vice that is being passed down to the subsequent generations, as well as to the state machine and its domestic sphere. The paper concludes by arguing that The Pillowman is a dark mirror of our own age that carries with it the old-felt fears about unchecked state authority and the eternally existing intoxication of toxicity and mutilation of the human spirit through narratives, which here are storytelling.