Underworld or the Underworld may refer to:
- The Spectral Realm - An alternative plane of existence to the Material Realm, extensively visited in Legacy of Kain: Soul Reaver, Soul Reaver 2 and Legacy of Kain: Defiance. The native realm of the dead, including specters and wraiths. Suggested by Amy Hennig to be synonymous with the Underworld.
- The Underworld (BO1) - An ambiguous location where Kain's soul is met by Mortanius in the opening of Blood Omen: Legacy of Kain.
- The Underworld (SR1) - A network of underground ruins beneath the Abyss and the Lake of the Dead in Legacy of Kain: Soul Reaver, and the game's starting area. Inhabited by the Elder God, and only accessible in the Spectral Realm.
- The Underworld (Defiance) - A large, cavernous area housing ruins beneath the Cemetery, and inhabited by the Elder God. Featured as Raziel's starting point in Legacy of Kain: Defiance, and only accessed in the Spectral Realm.
- Underworld (chapter) - the first gameplay chapter of Legacy of Kain: Soul Reaver, which takes place in the Underworld (SR1) location