Character mentioned in a song by King Crimson. Presumably a performer at the court of The Crimson King. What, if anything, he has to do with The King In Yellow is unknown, although some have linked the song to The Yellow Mythos. A Jester appears in The Prophet's Paradise.
A character in the non-Mythos novel, In The Courts of the Crimson Kings, cryptically refers to themselves as the Yellow Jester in the Court of the Crimson King (presumably a reference to the song above).