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.

Aztec mythology	Mictlan
Babylonian mythology	Kurnugia
Buddhist mythology	Naraka (also Niraya)
Celtic mythology	Annwn, Mag Mell
Chinese mythology	Yum gan (陰間) is an underworld though not necessarily negative like Diyu (地獄)
Christian mythology	Hades, Hell, Limbo, Paradise, Purgatory, Devil
Egyptian mythology	Aaru, Anubis, Duat, Neter-khertet
Estonian mythology	Toonela
Fijian mythology	see Melanesian mythology.
Finnish mythology	Tuonela
Greek mythology	Elysium, Asphodel Meadows, Hades, Tartarus
Hebrew Mythology	Sheol, Gehenna
Hindu mythology	Amaravati, Bhogavati, Naraka, Soma, Svarga, Patal
Inca mythology	Uku Pacha
Inuit mythology	Adlivun
Islamic mythology	Jahannam, Narr, Jannah, Barzakh, Araf
Japanese mythology	Yomi, Jigoku
Latvian mythology	Aizsaule
Maori mythology	Hawaiki
Mapuche mythology	Pellumawida, Degin, Wenuleufu, Ngullchenmaiwe
Mayan mythology	Metnal, Xibalba
Melanesian mythology	(includes Fijian) Bulu, Burotu, Murimuria, Nabangatai, Tuma
Norse mythology	Gimlé, Hel, Niflheim, Valhalla, Vingólf
Oromo mythology	Ekera
Philippine mythology	Kasanaan, Empiyerno
Polynesian mythology	Avaiki, Bulotu, Iva, Lua-o-Milu, Nga- Atua, Pulotu, Rangi Tuarea, Te Toi-o-nga-Ranga, Uranga-o-Te-Ra
Pueblo mythology	Shipap
Roman mythology	Avernus, Hades, Pluto
Slavic mythology	Peklo
Sumerian mythology	Dilmun, Kur, Ki-Gal
Vodou mythology	Guinee
Wagawaga mythology	Hiyoyoa

Rulers of the Underworld

(Note: this includes guardian-type creatures, ghosts, and spirits such as demons, veli, and Cerberus)

Aboriginal mythology	Baiame (Kamilaroi), Eingana
Akkadian mythology	Allu, Anu, Anunnaku, Ereshkigal, Etemmu, Gallu, Humbaba, Mamitu, Nergal, Utnapishtim
Albanian mythology	E Bukura e Dheut
Armenian mythology	Spandaramat
Aztec mythology	Mictlantecuhtli, Mictecacihuatl, Chalmecacihuilt, Chalmecatl
Babylonian mythology	Erra, Nergal, Ninlil, Sursunabu, Ur-shanabi, Utnapishtim
Balinese mythology	Batara Kala, Setesuyara
Bon mythology	gNyan
Buddhist mythology	Yama, Emma-O-, Yanluo
Canaanite mythology	Mot
Celtic mythology	Arawn, Bean Sidhe, Cernunnos, Cwn Annwn, Gwyn ap Nudd, Latiaran, Manannan mac Lir, Midir, Morrigan, Niamh, Pwyll, Sluagh, Tethra
Chinese mythology	Gu(i, Yanluo
Christian mythology	Angels, Demons, Devil, God, Michael, Saint Peter, Satan
Egyptian mythology	Aken, Aker (strictly only the gatekeeper), Am-heh, Amunet, Ammit, Andjety, Anubis, Apep, Apis, Astennu, Ha, Imiut (if the Imiut was ever considered a god), Isis, Mehen, Naunet, Nehebkau, Nephthys, Nun, Nut, Osiris, Ptah, Seker, Thoth
Elamite mythology	Jabru
Etruscan mythology	Charun, Culsu, Februus, Mania, Mantus, Nethuns, Tuchulcha, Vanth
Finnish mythology	Kalma, Kipu-Tyttö, Kivutar, Lovitar, Surma, Tuonen akka, Tuonetar, Tuoni, Vammatar
Greek mythology	Cerberus, Charon, Hades, Keres, Persephone, Styx, Thanatos, Tartaros
Georgian mythology	sasuleti
Haida mythology	Ta'xet, Tia
Hinduism	asuras, Bali, Chitragupta, devas, Durga, Naga (mythology), Rudra, Soma, Varuna, Vivasvat, Vritra, Yama
Hopi mythology	Kachina
Ibo mythology	Ala
Incan mythology	Supay, Vichama
Indonesian mythology	Dewi Shri, Ndara
Inuit mythology	Pana, Sedna
Islamic mythology	Hafaza, Huri, Iblis/Shaitan, Ifrit, Jinn, Mala'ikah, Peri
Japanese mythology	Hisa-Me, Hotoke, Ika-Zuchi-no-Kami, Jikininki, Shiko-Me, Shiti Dama, Shi-Ryo, Yama
Kassite mythology	Dur
Khmer mythology	Preas Eyssaur
Latvian mythology	Veli, Velu mate, Zemes mate
Levantine mythology	Mot
Lunda mythology	Kalunga
Maori mythology	Kewa
Maya mythology	Xibalba
Melanesian mythology	(includes Fijian mythology) Degei, Ratumaibulu, Samulayo
Narragansett mythology	Chepi
Navaho mythology	Estanatelhi
Niquiran mythology	Mictanteot
Norse mythology	Garm, Hel, Ran
Orokolo mythology	Kiavari
Persian mythology	Angra Mainyu, Azhi Dahaka, Peri
Philippine mythology (Look to the Christian Mythology for more information)	Demonyo Demon, Lucifer, Dyablo Diablo, Satan, Diyos God
Phoenician mythology	Horon
Phrygian mythology	Men
Polynesian mythology	Hikuleo, Hina, Hine-nui-te-Po, Kanaloa, Kiho, Makea Tutara, Mahiuki, Mahu-ike, Marama, Mauri, Merau, Milu, Miru, Rimu, Rohe (mythology), Whiro
Prussian mythology	Picullus
Pueblo mythology	Iyatiku
Roma (Gypsy) mythology
Roman mythology	Cerberus, Dea Tacita, Dis Pater, Egestes, Fames, Inferi Dii, Larenta, Letum, Libitina, Mors, Pluto, Proserpina, Viduus
Russian mythology	Baba Yaga, Koshchei
Saami mythology	Yambe-akka
Salish mythology	Amotken
Siberian mythology	Chebeldei, Kul
Slavic mythology	Crnobog, Flins, Marzana, Nyia
Sumerian mythology	Edimmu, Ekimmu, Endukugga, Enmesarra, Ereshkigal, Gidim, Gula, Irkalla, Kur, Namtar, Nergal, Neti, Nindukugga, Ninlil, Urshanabi, Ziusudra
Syrian mythology	Reshep
Tamil mythology	Cur
Thracian mythology	Heros
Vodou	Baron Cimetière, Baron La Croix, Baron Samedi, Ghede, Maman Brigitte, Marassa Jumeaux
Wagawaga mythology	Tumudurere
Yoruba mythology	Oya
Yurak mythology	Nga
Zuni mythology	Uhepono

References in popular culture

• The eighth Tomb Raider video game is titled Tomb Raider: Underworld.
• The setting for the Heroes in Hell shared world series of Bangsian Fantasy works by Janet Morris, C. J. Cherryh and others.
• The location of the captive Prince Rilian in The Silver Chair, of C. S. Lewis' Chronicles of Narnia series, is the Underland.
• The evil Outer Planes of the Dungeons & Dragons role-playing game.
• The Netherworld of the Playstation 2 videogame Disgaea: Hour of Darkness and other games of the series.
• The Underworld in the videogame Devil May Cry in Mission 19 "Enter the Corrupted World"
• The Underwhere in Super Paper Mario, where people whose "games have ended" go to.
• A high-end zone of the Guild Wars videogame series.
• A representation of hell in the Mortal Kombat videogame series, known as the Netherrealm.
• Underworld is the title of a Doctor Who story based on the legend of the Golden Fleece

This has influenced several gothic fiction texts.

• Karzahni, where poor Matoran workers were sent before Mata Nui's coming in the Bionicle mythos.
• In the television series Charmed, The Underworld was the residence of evil beings.
• From Star Trek, Gre'thor and Fek'lhr appear in Klingon mythology.
• In the television series Power Rangers: Mystic Force, the antagonists reside in a world which appears to be quite literally under the surface of the earth. Nevertheless, several ghoulish characters —such as Vampires, Werewolves, Zombies, Mummies and even someone very similar to Frankenstein's monster — act as primary residents (this version of the Underworld is more similar to Hades or Hell).
• Underworld (2003 film), directed by Len Wiseman and starring Kate Beckinsale about a war between vampires and werewolves. There was also a sequel - Underworld: Evolution (2006) and will be a prequel, Underworld 3: The Rise of the Lycans
• In the animated television series Chaotic, there's a tribe called the UnderWorld in perim.