An apparent entity mentioned, without great elucidation, twice in Robert Chambers' The King In Yellow:
- In The Repairer of Reputations, narrator Hildred Castaigne notes that Mr. Wilde refers to the name: "Then by degrees he led Vance along the ramifications of the Imperial family, from Naotalba and Phantom of Truth, to Aldones...".
- In The Yellow Sign, when the doomed characters Mr. Scott and Tessie are discussing The King In Yellow, they find that they are come into knowledge of the Yellow Sign and much else it entails: "...for we had understood the mystery of the Hyades and the Phantom of Truth was laid". Whether this implies a personage or a mere concept is unclear.
In More Light by James Blish, possibly intended to be the same as The Stranger.
Also the title of a booklet of poems and prose, and one of the poems in the booklet.
In Hymn To Hastur, it is stated to be the Ka of Hastur.
In The King in Yellow (Scott translation) functions as a narrator, leading a chorus of other Phantoms (including Happiness.)
See also Pallid Mask.