In the study of mythology and religion, the underworld (gr: κάτω κόσμος) is a generic term approximately equivalent to the lay term afterlife, referring to any place to which newly dead souls go. In most cultures the term refers to a neutral or dystopic realm of the afterlife, instead of a heavenly one. Sometimes the underworld is identified as "Hell" because Hell was thought to be under the Earth.
 Rulers of the Underworld
Hel, the location, shares a name with Hel, a female figure associated with the location. In late Icelandic sources, varying descriptions of Hel are given and various figures are described as being buried with items that will facilitate their journey to Hel after their death. In the Poetic Edda, Brynhildr's trip to Hel after her death is described and Odin, while alive, also visits Hel upon his horse Sleipnir. In the Prose Edda, Baldr goes to Hel upon death and subsequently Hermóðr uses Sleipnir to attempt to retrieve him. "Hel-shoes" are described in Gísla saga.
Holle is theorized as an ancient Germanic supreme goddess of birth, death and reincarnation who predates most of the Germanic pantheon, dating back to the Neolithic before Indo-European invasion of Europe. She also appears as "Frau Holle" ("Mother Hulda") in Grimm's Fairy Tale #24. Alternative names for this goddess include Hel, Holla, Holda, Hulda, Hilde, Hilda, and many others.