Arcane books of forbidden lore, disturbing secrets in  the family bloodline, and terrors so unspeakable the very  thought of them might drive you mad. By now, these have become standard  elements in many modern horror stories. But they were largely popularized  by a single author– one whose name has become an adjective for the particular type of  terror he inspired. Born in Providence, Rhode Island in 1890, Howard Phillips Lovecraft grew up  admiring the Gothic horror stories written by Edgar Allan Poe  and Robert Chambers. But by the time he began writing in 1917, World War I had cast a long  shadow over the arts. People had seen real horrors, and were no longer frightened  of fantastical folklore. Lovecraft sought to invent a  new kind of terror, one that responded to the rapid  scientific progress of his era. His stories often used scientific elements to lend eerie plausibility. In "The Colour out of Space," a strange meteorite falls near  a farmhouse, mutating the farm into a  nightmarish hellscape. Others incorporated scientific  methodology into their form. "At the Mountains of Madness" is written  as a report of an Antarctic expedition that unearths things better  left undiscovered. In others, mathematics themselves  become a source of horror, as impossible geometric configurations wreak havoc on the minds of  any who behold them. Like then-recent discoveries of  subatomic particles or X-rays, the forces in Lovecraft’s fiction  were powerful, yet often invisible and indescribable. Rather than recognizable monsters, graphic violence, or startling shocks, the terror of “Lovecraftian” horror lies  in what’s not directly portrayed– but left instead to the dark depths  of our imagination. Lovecraft’s dozens of short stories,  novellas, and poems often take place in the same  fictional continuity, with recurring characters, locations,  and mythologies. At first glance, they appear to be set within Lovecraft’s  contemporary New England. But beneath the surface of this seemingly  similar reality lie dark masters, for whom Earth’s inhabitants  are mere playthings. More like primordial forces  than mere deities, Lovecraft’s Great Old Ones lurk at  the corners of our reality. Beings such as Yog-Sothoth, “who froths as primal slime  in nuclear chaos beyond the nethermost outposts  of space and time.” Or the blind, idiot god Azathoth, whose destructive impulses are  stalled only by the “maddening beating of vile drums and the thin monotonous whine  of accursed flutes.” These beings exist beyond our  conceptions of reality, their true forms as inscrutable  as their motives. Lovecraft’s protagonists– often researchers, anthropologists,  or antiquarians– stumble onto hints of their existence. But even these indirect glimpses are  enough to drive them insane. And if they survive, the reader is left with no feeling of  triumph, only cosmic indifference– the terrible sense that we are  but insignificant specks at the mercy of unfathomable forces. But perhaps the greatest power  these creatures had was their appeal to Lovecraft’s  contemporaries. During his lifetime, Lovecraft corresponded  with other writers, encouraging them to employ elements and  characters from his stories in their own. References to Lovecraftian gods  or arcane tomes can be found in many stories  by his pen pals, such as Robert E. Howard and Robert Bloch. Today, this shared universe is called  the Cthulhu Mythos, named after Lovecraft’s infamous blend  of dragon and octopus. Unfortunately, Lovecraft’s fear of the unknown found  a less savory expression in his personal views. The author held strong racist views, and some of his works include  crude stereotypes and slurs. But the rich world he created would  outlive his personal prejudices. And after Lovecraft’s death, the Cthulhu Mythos was adopted  by a wide variety of authors, often reimagining them from  diverse perspectives that transcend the author’s prejudices. Despite his literary legacy, Lovecraft was never able to  find financial success. He died unknown and penniless  at the age of 46– a victim of the universe’s cosmic  indifference. But his work has inspired numerous  short stories, novels, tabletop games, and cultural icons. And as long as humans feel a sense of  dread about our unknown future, Lovecraftian horror will have a place in  the darkest corners of our imagination.