This thesis suggests the possibility that psychoanalytic frameworks may prove insufficient to apprehend the workings of post-millennial horror. Through a sustained exploration of how affect theory may be applied to horror, I propose a new affective corporeal model that accounts for the impact of recent films such as Saw (James Wan, 2004) and Hostel (Eli Roth, 2005). I also explore how such a theoretical approach exceeds cognitivism in favour of an understanding of the genre founded on phenomenology, Pain Studies and Deleuze and Guattari's notion of the 'body without organs'. This thesis finds the seed for spectatorial affect in the dramatic tradition and its corporeal instantaneity. It thus also offers a brief genealogy of affective mutilation as it is evolves in Greek tragedy, Shakespearean drama, the Gothic stage, the theatre of the grand guignol and Artaud's theatre of cruelty. Case studies of representative texts shed light on the affective innovations that cinema draws from in order to convey similar participatory experiences. I consider how contemporary horror appeals directly to the somatic body through a focus on moments of extreme mutilation. I therefore find it necessary to complicate traditional views of the genre as sadistic, and offer a more nuanced conceptualisation of visual mutilation that allows for fluid, organic and non-representational connections between on-screen bodies and spectators. Issues of cinematic identification and alignment are addressed in relation to key texts of the 'torture porn' and 'snuff films' subgenres. Ultimately, I show that the affective corporeal model may be used to analyse a number of texts which utilize and manipulate the organic aspects of human embodiment. Precisely because the chosen texts have not been traditionally studied under an affective lens before, the results render an innovative re-evaluation of their cultural and spectatorial dimensions.