H.P. Lovecraft was an American writer principally known for his weird fiction, a British and American sub-genre of speculative narrative that he helped both characterize and, as a critic, define. In his tales, Lovecraft blended elements of fantasy, horror, and science fiction into a strikingly original, infectious, and highly influential narrative universe. Lovecraft’s weird fiction is characterized by a fascination with occult grimoires and forbidden knowledge; a pantheon of bizarre extraterrestrial pseudo-gods who are essentially inimical to human life; a nostalgic attachment to the history and landscape of New England; and a heavily racialized concern with human degeneration and atavistic cults. In contrast to the implicit supernaturalism of ghost stories or the gothic tale, the metaphysical background of Lovecraft’s stories is a “cosmic indifferentism” rooted in the nihilistic and atheist materialism that Lovecraft professed at great length in his fascinating letters. This lifelong philosophical stance led Lovecraft to embrace the disillusioning powers of science, but also to pessimistically anticipate science’s ultimate evisceration of human cultural norms and comforts. His weird tales were imaginative diversions from this nihilism, but their horror reflected it as well. Lovecraft’s literary vision was also amplified by the vivid, often nightmarish, and intensely detailed dreams he experienced throughout his life. A crucial influence on his fiction, Lovecraft’s dreaming can be seen as a phantasmic supplement to the reductive naturalism of his intellectual outlook, lending his work an uncanny dynamism that helps explain its continued power to stimulate thought, imagination, and cultural creation.