From Wikipedia: Howard Phillips Lovecraft (August 20, 1890 – March 15, 1937), of Providence, Rhode Island, was an American author of fantasy, horror, and science fiction.
Lovecraft’s major inspiration and invention was cosmic horror: life is incomprehensible to human minds and the universe is fundamentally alien. Those who genuinely “reason”, like his protagonists, gamble with sanity. Lovecraft has become a cult figure for his Cthulhu Mythos, a series of loosely interconnected fictions featuring a pantheon of human-invalidating entities, as well as the famed Necronomicon, a grimoire of magical rites and forbidden lore. His works were deeply pessimistic, fabricating a mythos that challenged the values of the Enlightenment, Romanticism, and Christianity.
Although Lovecraft’s readership was limited during his life, his reputation has grown over the decades, and he is now commonly regarded as one of the most influential horror writers of the 20th Century, exerting widespread and indirect influence, and frequently compared to Edgar Allan Poe in the tone of his writing style.