H.P. (Howard Philips) Lovecraft was a American Horror writer, and is considered by most sane people the creator of Cthulhu and the Mythos, until his untimely death by cancer in the small intestine. He died on March 17th, 1937.
Through his writing, he predicted events, and passed them off as writing and writing alone, without realizing his "creations" were always watching him in the shadows, and driving his hand to write.
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.