Wikipedia
The Underdark is a fictional setting which has appeared in Dungeons & Dragons role-playing campaigns and Dungeons & Dragons-based fiction books, including the Legend of Drizzt series by R. A. Salvatore. It is described as a vast subterranean network of interconnected caverns and tunnels, stretching beneath entire continents and forming an underworld for surface settings.
The Underdark sourcebook for the Forgotten Realms campaign setting of the 3.5 edition of the Dungeons & Dragons role-playing game.
Underdark – a death metal (sophisticated death metal) band from Przemysl, Poland. The debut album In the Name of Chaos, (released in Poland by Psycho Records in 2009) received good feedback in Polish underground and mainstream press. Since December 2010, it has been distributed worldwide under Greek label Sleaszy Rider Records.