In the standard cosmology of the Dungeons & Dragons fantasy role-playing game, Pandemonium (or, the Windswept Depths of Pandemonium) is the Outer plane where Chaotic Evil and Chaotic Neutral petitioners are sent after death. Pandemonium is a large, complex cavern that never ends. Compounding this problem, howling winds drive most of its residents mad. There are few creatures that are native to this plane; those individuals who do live there usually have no choice in the matter. It is one of a number of alignment-based Outer Planes that form part of the standard Dungeons & Dragons (D&D) cosmology, used in the Planescape, Greyhawk and most editions of the Forgotten Realms campaign settings.
In the Planescape campaign setting, Pandemonium houses the headquarters for the Bleak Cabal faction.
The plane known as Pandemonium was mentioned for the first time by name in the article "Planes: The Concepts of Spatial, Temporal and Physical Relationships in D&D", in The Dragon #8, released July 1977. The plane was mentioned again in an appendix of the known planes of existence in the original (1st edition) AD&D Players Handbook, published in June 1978, where it was described as "The Planes of Pandemonium of chaotic evil neutrals".
Each of the four layers of Pandemonium is successively deeper within the caverns.
The gnoll deity Gorellik wanders throughout Pandemonium.