Nyarlathotep is a name used for various characters in the works of H. P. Lovecraft and other writers. The character is commonly known in association with its role as a malign deity in the Cthulhu Mythos fictional universe, where it is known as the Crawling Chaos. First appearing in Lovecraft's 1920 prose poem of the same name, he was later mentioned in other works by Lovecraft and by other writers and in the tabletop roleplaying games making use of the Cthulhu Mythos. Later writers describe him as one of the Outer Gods.
In his first appearance in "Nyarlathotep", he is described as a "tall, swarthy man" who resembles an ancient Egyptian pharaoh. In this story he wanders the earth, seemingly gathering legions of followers, the narrator of the story among them, through his demonstrations of strange and seemingly magical instruments. These followers lose awareness of the world around them, and through the narrator's increasingly unreliable accounts the reader gets an impression of the world's collapse.
Nyarlathotep subsequently appears as a major character in "The Dream Quest of Unknown Kadath" (1926/27), in which he again manifests in the form of an Egyptian Pharaoh when he confronts protagonist Randolph Carter.
The twenty-first sonnet of Lovecraft's poem-cycle "Fungi from Yuggoth" (1929/30) is essentially a retelling of the original prose poem.
In "The Dreams in the Witch House" (1933), Nyarlathotep appears to Walter Gilman and witch Keziah Mason (who has made a pact with the entity) in the form of "the 'Black Man' of the witch-cult," a black-skinned avatar of the Devil described by witch hunters.
Nyarlathotep is also mentioned in "The Rats in the Walls" as a faceless god in the caverns of earth's center.
Finally, in "The Haunter of the Dark" (1936), the nocturnal tentacled, bat-winged monster dwelling in the steeple of the Starry Wisdom sect's church is identified as another form, or manifestation of, Nyarlathotep.
Though Nyarlathotep appears as a character in only four stories and two sonnets (which is more than any other of Lovecraft's gods), his name is mentioned frequently in other works. In "The Whisperer in Darkness" Nyarlathotep's name is spoken frequently by the Mi-Go in a reverential or ritual sense, including dressing as a man, indicating that at its end the whisperer is him, and in "The Shadow Out of Time" (1936), the "hideous secret of Nyarlathotep" is revealed to the protagonist during his period spent in pre-cambrian earth by Khephnes, another prisoner of the Great Race.
Despite similarities in theme and name, Nyarlathotep does not feature at all in Lovecraft's story "The Crawling Chaos", (1920/21) an apocalyptic narrative written in collaboration with Winifred V. Jackson (aka Elizabeth Berkeley).
Nyarlathotep differs from the other beings in a number of ways. Most of them are exiled to stars, like Yog-Sothoth and Hastur, or sleeping and dreaming like Cthulhu; Nyarlathotep, however, is active and frequently walks the Earth in the guise of a human being, usually a tall, slim, joyous man. He has "a thousand" other forms, most of these reputed to be maddeningly horrific. Most of the Outer Gods have their own cults serving them; Nyarlathotep seems to serve these cults and take care of their affairs in their absence. Most of them use strange alien languages, while Nyarlathotep uses human languages and can be mistaken for a human being. Most importantly, while the other Outer Gods and Great Old Ones are often described as mindless or unfathomable, rather than truly malevolent, Nyarlathotep delights in cruelty, is deceptive and manipulative, and even cultivates followers and uses propaganda to achieve his goals. In this regard, he is probably the most human-like among them.
Nyarlathotep enacts the will of the Outer Gods, and is their messenger, heart and soul; he is also a servant of Azathoth, his father, whose wishes he immediately fulfills. Unlike the other Outer Gods, causing madness is more important and enjoyable than death and destruction to Nyarlathotep. It is suggested by some that he will destroy the human race and possibly the earth as well.