First Published 15 December 2020
This article is relative to the world of Oerth.

Greyhawk, also known as 'The World Of Greyhawk', was for many years the only official world of D&D. Although technically not the first campaign world developed for Dungeons & Dragons - game co-creator Dave Arneson's Blackmoor campaign predated it by over a year - the world of Greyhawk is closely identified with the development of the game from 1972 until 2008. The world itself started as a simple dungeon under a castle designed by game co-creator Gary Gygax for the amusement of his children and friends, but it rapidly expanded to include not only a complex multi-layered dungeon environment, but also the nearby city of Greyhawk, and eventually an entire world.

In addition to the campaign world, which was published in several editions over twenty years, Greyhawk was also used as the setting for many adventures published in support of the game, as well as for RPGA's massively shared Living Greyhawk campaign from 2000-2008.