|Howard Phillips Lovecraft practically dominated weird fiction in American proz till his death in 1937, and his mythos still march on in the hands of friends and pupils like Bob Bloch, Clark Ashton Smith, and August Derleth, who have added independently to the canon. The Mythos centers around the exile to Earth of the Great Old Ones, who had rebelled against the Elder Gods (not those of the Shaver Mythos, fergawdsake) and still scheme to try again. A touchstone for stories of this cycle is the exclamation "Ia! Yog-Sothoth!"; it's part of the ritual for opening the Path Whereby the Spheres Meet (Yog-Sothoth, as every good fan should know, is the Key and the Guardian of that Path's Gate) and rarely fails of utterance. The Necronomicon of Abdul Alhazred, the mad Arab, is a source of much knowledge of the Great Old Ones; other books of incredible secrets like the R'lyeh Text, Comte D'Erlette's Cultes des Goules, Freidrich von Juntztz' Unausprechlichen Kulten, and the Pnakotic Manuscripts have also proved baneful to over-curious folk. Dreadful events center around Arkham, where Miskatonic University has one of the few known copies of the Necronomicon, and whose neighboring towns Dunwich and Innsmouth are effectively in the hands of the Cthulhu Cult, as inquisitive scientists find out too late. The Great Old Ones themselves are numerous; important ones are Nyarlathotep, Their messenger, who originated the human race; Yog-Sothoth; Azathoth the Lord of All (a "blind, idiot god" who, Fritz Leiber conjectures, symbolizes the mechanistic cosmos); and Cthulhu the sea-god -- a being very like a cross between an octopus and a jellyfish, tho capable of "lumbering slobberingly" in pursuit of humans and such tasty morsels. Other approximately mortal creatures like the Deep Ones, Shaggoths, Tcho-Tcho People and suchlike which your compiler would rather not think about are more or less servants of the Great Old Ones.
Pronunciation of such names as Cthulhu has worried many fans -- Cthulhu, incidentally, was the first to be the subject of one of HPL's stories, whence the mythos are sometimes called "Cthulhu Mythos" -- who were not helped by Lovecraft's insistence that the name was rendered into those English letters phonetically. This is nonsense -- C has no definite phonetic value in English -- but would make the original some such sound as Kh-thool-hoo or Ss-thool- hoo. "Sykora used to pronounce it with a whistle in the middle; I heard him", says Damon Knight. "Thool-thool" is the only so-called authentic pronunciation Coswal has heard, which obviously evades the C problem. Harry Warner cites a valuable source of information, approved by weird authors: "Just give a click with the tongue at the start of the word, just as you do with many Russian words, and ignore the second H, with accent on the first syllable. I've never heard it pronounced, you understand, so that knowledge must be instinctive inheritance from the Old Days."