Kadath is a mountain crowned by an onyx castle, and the home of the dream-gods of Earth, otherwise known as the "Great Ones".
Created by H. P. Lovecraft, Kadath is mentioned in several of his stories, including both the Dream Cycle series and more "science fictional" pieces, such as At the Mountains of Madness. It was first mentioned in print in "The Dunwich Horror" (written after the Dream Cycle series, but published earlier).
In Lovecraft's fiction, it is most often referred to as "Kadath in the cold waste", a location unknown to humans and other mortal races.
In the works of August Derleth, Kadath in the Cold Waste exists "in time and space conterminously with a portion of Asia". (AWD: "The Whippoorwills in the Hills", "The Seal of R'lyeh")
Behind the Mythos[]
Kadath's precise location in the universe is uncertain; there is even confusion over whether it exists in the dream-world or the waking world. The Zoogs couldn't tell whether "the cold waste" is located in the Dreamlands of Earth or another world (HPL: The Dream-Quest of Unknown Kadath). However, in Lovecraft's At the Mountains of Madness, it is hinted that the mountain ranges beyond the Antarctic plateau of Leng may hide the location of Kadath. In The Mound, Zamacona y Nuñez's narrative likewise identifies Kadath as a mountain near the South Pole. But in The Dream-Quest of Unknown Kadath, Randolph Carter finds it far of north from the Leng and Inganok.
Sylvan Phillips's map places "Kadath in the Cold Waste" in the vicinity of Mongolia, north of the Plateau of Leng in Central Asia, but also explicitly notes it as being "in space-time continua: coterminous". (AWD: "The Seal of R'lyeh")
Another source states that Kadath is neither in the waking world nor part of the Dreamlands, as it's "not truly contiguous with any space men know or dream of". (EXP: "In 'Ygiroth")
In the Doctor Who universe, "Kadath in the Cold Wastes" is a city where the false Azathoth was imprisoned on the planet Ry'leh. (EXP: All-Consuming Fire)