Exploring links between speculative materialist philosophy and the writings of H. P. Lovecraft, this article tracks how theories of horror have been defined, developed and transformed in relation to literary and philosophical notions of the ‘Thing’. Moving from Kantian ideas of ‘noumenon’ to Gothic Things and from post-structuralist engagements with subjective and cultural limits, the argument plots the interrelationship between speculative realism and Lovecraft in terms of changing ideas of matter, science and the human.