In ancient Greek religion and myth, Pluto (Πλούτων, Ploutōn) was a name for the ruler of the underworld; the god was also known as Hades, a name for the underworld itself. This deity has two major myths: in Greek cosmogony, he received the rule of the underworld in a three-way division of sovereignty over the world, with his brothers Zeus ruling Heaven and Poseidon the Sea; and he abducts Persephone to be his wife and the queen of his realm. In other myths, he plays a secondary role, mostly as the possessor of a quest-object.
The name Ploutōn was frequently conflated with that of Plutus (Πλοῦτος, Ploutos), a god of wealth, because mineral wealth was found underground, and because as a chthonic god Pluto ruled the deep earth that contained the seeds necessary for a bountiful harvest. Ploutōn became a more positive way to talk about the ruler of the underworld, and the name was popularized through the mystery religions and philosophical systems influenced by Plato, the major Greek source on its meaning.
Pluto (genitive Plutonis) is the Latinized form of the Greek Ploutōn. Pluto's Roman equivalent is Dis Pater, whose name is most often taken to mean "Rich Father." Pluto was also identified with the obscure Roman Orcus, like Hades the name of both a god of the underworld and the underworld as a place. The name Pluto is sometimes used for the ruler of the dead in Latin literature, leading some mythology handbooks to assert misleadingly that Pluto was the Roman counterpart of Hades, rather than an adopted Greek name identified with Dis Pater or Orcus. Pluto (French Pluton and Italian Plutone) is commonly used as the name of the classical ruler of the underworld in subsequent Western literature and other art forms.
Plouton was one of several euphemistic names for Hades, described in the Iliad as the god most hateful to mortals. Plato says that people prefer the name Plouton, "giver of wealth," because the name of Hades is fear-provoking. The name was understood as referring to "the boundless riches of the earth, both the crops on its surface—he was originally a god of the land—and the mines hidden within it." What is sometimes taken as "confusion" of the two gods Plouton and Ploutos ("Wealth") held or acquired a theological significance in antiquity. As a lord of abundance or riches, Pluto expresses the aspect of the underworld god that was positive, symbolized in art by the "horn of plenty" (cornucopia), by means of which Plouton is distinguished from the gloomier Hades.
The Roman poet Ennius (ca. 239–169 BC), the leading figure in the Hellenization of Latin literature, considered Pluto a Greek god to be explained in terms of the Roman equivalents Dis Pater and Orcus. It is unclear whether Pluto had a literary presence in Rome before Ennius. Some scholars think that rituals and beliefs pertaining to Pluto entered Roman culture with the establishment of the Saecular Games in 249 BC, and that Dis pater was only a translation of Plouton. In the mid-1st century BC, Cicero identifies Pluto with Dis, explaining that "The earth in all its power and plenty is sacred to Father Dis, a name which is the same as Dives, 'The Wealthy One,' as is the Greek Plouton. This is because everything is born of the earth and returns to it again."
During the Roman Imperial era, the Greek geographer Strabo (1st century) makes a distinction between Pluto and Hades. In writing of the mineral wealth of ancient Iberia (Roman Spain), he says that among the Turdetani, it is "Pluto, and not Hades, who inhabits the region down below." In the discourse On Mourning by the Greek author Lucian (2nd century), Pluto's "wealth" is the dead he rules over in the abyss (chasma); the name Hades is reserved for the underworld itself.
The best-known myth involving Pluto or Hades is the abduction of Persephone, also known as Kore ("the Maiden"). The earliest literary versions of the myth are a brief mention in Hesiod's Theogony and the extended narrative of the Homeric Hymn to Demeter; the ruler of the underworld is named as Hades ("the Hidden One") in both these works. Hades is an unsympathetic figure, and Persephone's unwillingness is emphasized. Increased usage of the name Plouton in religious inscriptions and literary texts reflects the influence of the Eleusinian Mysteries, which treated Pluto and Persephone as a divine couple who received initiates in the afterlife; as such, Pluto was disassociated from the "violent abductor" of Kore.
The most influential version of the abduction myth is that of Ovid, who tells the story in both the Metamorphoses (Book 5) and the Fasti (Book 4). Another major retelling, also in Latin, is the long unfinished poem De raptu Proserpinae of Claudian. Ovid uses the name Dis, not Pluto in these two passages, and Claudian uses Pluto only once; translators and editors, however, sometimes supply the more familiar "Pluto" when other epithets appear in the source text. The mythography traditionally known as the Library of Apollodorus (in Greek, 2nd/1st century BC) and the Fables of Hyginus (in Latin, 1st century BC) name the god as Pluto instead of Hades. The abduction myth was a popular subject for Greek and Roman art, and recurs throughout Western art and literature, where the name "Pluto" becomes common (see Pluto in Western art and literature below). Narrative details from Ovid and Claudian influence these later versions in which the abductor is named as Pluto, especially the role of Venus and Cupid in manipulating Pluto with love and desire. Throughout the Middle Ages and Renaissance, and certainly by the time of Natale Conti's influential Mythologiae (1567), the traditions pertaining to the various rulers of the classical underworld coalesced into a single mythology that made few if any distinctions among Hades, Pluto, Dis, and Orcus.