Judges Guild is a game publisher that has been active since 1976. The company created and sold many role-playing game supplements, periodicals and related materials. During the late 1970s and early 1980s the company was one of the leading publishers of Dungeons & Dragons related materials. Its flagship product, City State of the Invincible Overlord, was the first published RPG supplement to feature a fully developed city environment. The supplement was followed closely by numerous ancillary cities, maps, and other materials published by Judges Guild.