The Circle of Eight is an organization of wizards in the World of Greyhawk setting. They are based in the Flanaess, the easternmost portion of Oerik. The Circle of Eight's chief purpose seems to be the preservation of the balance of power between the forces of Good, Evil, Law, and Chaos in the Flanaess, ensuring that one does not dominate the other for an extended period of time. To this end, the Circle often works behind the scenes, especially when aiding the cause of evil.
Despite the organization's name, the Circle of Eight actually has nine members. The Circle consists of eight powerful wizards and their leader, Mordenkainen the archmage. In fact, the group is sometimes referred to as "Mordenkainen and the Circle of Eight."