Greyhawk (supplement)

Greyhawk is a supplementary rulebook written by Gary Gygax and Robert J. Kuntz for the original edition of the Dungeons & Dragons (D&D) fantasy role-playing game. It has been called "the first and most important supplement" to the original D&D rules. Although the name of the book was taken from the home campaign supervised by Gygax and Kuntz based on Gygax's imagined Castle Greyhawk and the lands surrounding it, Greyhawk did not give any details of the castle or the campaign world; instead, it explained the rules that Gygax and Kuntz used in their home campaign, and introduced a number of character classes, spells, concepts and monsters used in all subsequent editions of D&D.