Lovecraft is best known for creating the Cthulhu Mythos, a shared fictional universe of ancient, indifferent gods. His work, including 'The Call of Cthulhu' and 'At the Mountains of Madness,' shifted horror away from the supernatural toward a sense of existential dread in a vast, uncaring cosmos. While largely unrecognised during his life, his influence on horror and science fiction after his death has been immense, shaping the work of Stephen King and numerous filmmakers.