Castle Greyhawk is one of the central dungeon settings in the fictional World of Greyhawk campaign setting for the Dungeons & Dragons roleplaying game. The Castle was originally developed by Gary Gygax, for his own campaign and later detailed for publication. Castle Greyhawk is also the name of a 1988 Dungeons & Dragons adventure module that created a treatment of the Castle for the public to use. In 2005, Gygax announced the release of "," his new treatment of the dungeon.