While Greyhawk is perhaps not the first setting to be used in a Dungeons & Dragons game (that honor likely goes to Dave Arneson’s Blackmoor). But the world of Oerth that it’s a part of is the first and most famous to appear in the early official supplements for the tabletop role-playing game. Some of the most renowned D&D modules take place in this setting developed by Gary Gygax, including the classic trilogy Against the Giants and other pieces of D&D history like The Temple of Elemental Evil. D&D 5.5, launched in 2024, returned to Oerth with Greyhawk as the default setting of the core rulebooks.