These deities or gods are related to the subterranean underworld, where souls of the dead go. They are also associated with sacrificial rituals, when the cults made offerings to the gods in or beneath the earth itself by throwing animals into the underground pit and pouring liquids into it.
Amphiaraus - war hero of the Seven Against Thebes who was swallowed by Gaea and transformed into oracular spirit of the Underworld.
Ascalaphus - son of Acheron and Orphne who was an orchardist in the Underworld. After notifying other gods that Persephone had eaten pomegranate, he was in revenge transformed into a screech-owl by Demeter.
Charon - ferryman of Hades who was carrying the souls of the dead across the rivers Styx and Acheron to the underworld.
Erebus - primeval god of darkness. He was one of the first-born gods and he encircled the underworld by filling the hollows of the earth.
Erinyes - the Furies, goddesses of retribution. They were born from Uranus' blood, spilled on the earth. Their names were Alecto (the unceasing one), Tisiphone (avenger of murder) and Megaera (the jealous one).
Hecate - goddess of magic, witchcraft, the night, ghosts and necromancy. She was born to the titans Perses and Asteria. Hecate helped Demeter in search of her daughter Persephone and later, when Persephone was reunited with Demeter, became a minister and companion of Persephone.
Judges of the Dead - once sons of Zeus were given their privileged status after death. Their names were Aiakos (a former mortal king of Aegina, a guardian of the keys of Hades and a judge of the men of Europe), Minos (a former mortal king of Crete and a judge of the final vote), and Rhadamanthys (a former mortal lawmaker and a judge of the men of Asia).
Keuthonymos - mysterious underworld spirit who guarded the oxen of Hades. He was a father of Menoites.
Lampades - torch-bearing Underworld nymphs who accompanied Hecate on her travels. It is said that they were a gift from Zeus to Hecate for siding with the Olympians in the Titanomachy. Most known is Gorgyra (Orphne), a Lampad nymph of Hades and a mother of Ascalaphus
Macaria - goddess of blessed death. She was a daughter of Hades. She had the same purpose as Thanatos but, unlike him, she came to reap the souls of the blessed.
Melinoe - underworld goddess who presided over the propitiations offered to the ghosts of the dead. It is said that she was a daughter of Zeus and Persephone.
Menoetes - underworld spirit who herded the cattle of Hades. He was encountered by Heracles who crashed his bones but let him go on the request of Persephone.
Nyx - primeval goddess of night. She was one of the first-born gods and a mother of other primeval gods and goddesses such as Aether, Hemera, Moros, Thanatos and more. She was hidden in the shadows of the world and only ever seen in glimpses.
Palici - twin chthonic gods who presided over the geysers and underworld entrance in Sicily. Followers came to their sacred place which was centered around three small lakes that emitted sulphurous vapors.
Persephone - originally she was an agricultural goddess of spring growth but she became bound to the underworld upon eating pomegranate. She became a queen of the underworld and a wife of Hades. She spent one third of the year in the underworld with Hades.
Tartarus - primeval god of the dark, personification of deep dark abyss way beyond the Underworld. It was used as a dungeon for tormenting the souls of the worst villans.
Thanatos - god of non-violent death or personification of death. He was like a reaper who comes for the souls of dying people. Thanatos was also a minister of Hades.