Aklo is the name of a fictional language that has been used by many authors from its first reference in 1899. The language is said to have mystical powers. Aklo was first mentioned by Arthur Machen in his 1899 story "The White People". Aklo was mentioned but not described in detail by Machen, being noted in passing by the story's narrator as part of a secretive game or ritual. In The Illuminatus! Trilogy by Robert Shea and Robert Anton Wilson, Aklo appears as a language used in Black Masses and by the Illuminati.