"Celephaïs" (/ˈsɛləfeɪs/) is a fantasy story by American horror fiction writer H. P. Lovecraft, written in early November 1920 and first published in the May 1922 issue of the Rainbow.

The title refers to a fictional city that later appears in other Dream Cycle stories, including Lovecraft's novella The Dream-Quest of Unknown Kadath (1926).

In The Dream-Quest of Unknown Kadath, Randolph Carter pays a visit to Kuranes, finding that the great dreamer has grown so homesick for his native Cornwall, he has dreamed parts of Celephaïs to resemble the land of his boyhood.

"[1] The story resembles a tale by Lord Dunsany, The Coronation of Mr. Thomas Shap in The Book of Wonder, in which the title character becomes more and more engrossed in his imaginary kingdom of Larkar until he begins to neglect business and routine tasks of daily living, and ultimately is placed in a madhouse.

Galleys from the port of Celephaïs go everywhere in the Dreamlands, but especially to the cloud-kingdom Serannian, reaching its harbor by sailing into the sky where the Cerenerian Sea meets the horizon.