Hades (ˈheɪdiːz/; from Greek ᾍδης (older form Ἀϝίδης), Hadēs, originally Ἅιδης, Haidēs or Άΐδης, Aidēs (Doric Ἀΐδας Aidas), meaning "the unseen") was the ancient Greek god of the underworld. The genitive ᾍδου, Haidou, was an elision to denote locality: "[the house/dominion] of Hades". Eventually, the nominative came to designate the abode of the dead. In Greek mythology, Hades is the oldest male child of Cronus and Rhea. According to myth, he and his brothers Zeus and Poseidon defeated the Titans and claimed rulership over the cosmos, ruling the underworld, air, and sea, respectively; the solid earth, long the province of Gaia, was available to all three concurrently.
Hades was also called "Plouton" (Greek: Πλούτων, gen.: Πλούτωνος, meaning "Rich One"), a name which the Romans Latinized as Pluto. The Romans would associate Hades/Pluto with their own chthonic gods, Dis Pater and Orcus. The corresponding Etruscan god was Aita. Symbols associated with him are the Helm of Darkness and the three-headed dog, Cerberus. The term hades in Christian theology (and in New Testament Greek) is parallel to Hebrew sheol (שאול, grave or dirt-pit), and refers to the abode of the dead. The Christian concept of hell is more akin to and communicated by the Greek concept of Tartarus, a deep, gloomy part of hades used as a dungeon of torment and suffering.
In Greek mythology, Hades (the "unseen"), the god of the underworld, was a son of the Titans, Cronus and Rhea. He had three sisters, Demeter, Hestia, and Hera, as well as two brothers, Zeus, the youngest of the three, and Poseidon, collectively comprising the original six Olympian gods. Upon reaching adulthood, Zeus managed to force his father to disgorge his siblings. After their release the six younger gods, along with allies they managed to gather, challenged the elder gods for power in the Titanomachy, a divine war. Zeus, Poseidon, and Hades received weapons from the three Cyclopes to help in the war: Zeus the thunderbolt, Hades the Helm of Darkness, and Poseidon the trident. The night before the first battle, Hades put on his helmet and, being invisible, slipped over to the Titans' camp and destroyed their weapons. The war lasted for ten years and ended with the victory of the younger gods. Following their victory, according to a single famous passage in the Iliad (xv.187–93), Hades and his two brothers, Poseidon and Zeus, drew lots for realms to rule. Zeus got the sky, Poseidon got the seas, and Hades received the underworld, the unseen realm to which the dead go upon leaving the world as well as any and all things beneath the earth.
Hades obtained his eventual consort and queen, Persephone, through trickery, a story that connected the ancient Eleusinian Mysteries with the Olympian pantheon in a founding myth for the realm of the dead. Helios told the grieving Demeter that Hades was not unworthy as a consort for Persephone:
"Aidoneus, the Ruler of Many, is no unfitting husband among the deathless gods for your child, being your own brother and born of the same stock: also, for honor, he has that third share which he received when division was made at the first, and is appointed lord of those among whom he dwells."
— Homeric Hymn to Demeter
Despite modern connotations of death as evil, Hades was actually more altruistically inclined in mythology. Hades was often portrayed as passive rather than evil; his role was often maintaining relative balance. Hades ruled the dead, assisted by others over whom he had complete authority. He strictly forbade his subjects to leave his domain and would become quite enraged when anyone tried to leave, or if someone tried to steal the souls from his realm. His wrath was equally terrible for anyone who tried to cheat death or otherwise crossed him, as Sisyphus and Pirithous found out to their sorrow. Besides Heracles, the only other living people who ventured to the Underworld were all heroes: Odysseus, Aeneas (accompanied by the Sibyl), Orpheus, Theseus with Pirithous, and, in a late romance, Psyche. None of them were pleased with what they witnessed in the realm of the dead. In particular, the Greek war hero Achilles, whom Odysseus conjured with a blood libation, said:
"O shining Odysseus, never try to console me for dying.
I would rather follow the plow as thrall to another
man, one with no land allotted to him and not much to live on,
than be a king over all the perished dead."
— Achilles' soul to Odysseus. Homer, Odyssey 11.488-491