Greek underworld Geography
In Greek mythology, Erebus /ˈɛrəbəs/, also Erebos (Greek: Ἔρεβος, “deep darkness, shadow”), was often conceived as a primordial deity, representing the personification of darkness; for instance, Hesiod‘s Theogony identifies him as one of the first five beings in existence, born of Chaos. Erebus features little in Greek mythological tradition and literature, but is said to have fathered several other deities with Nyx; depending on the source of the mythology, this union includes Aether,Hemera, the Hesperides, Hypnos, the Moirai, Geras, Styx, Charon, and Thanatos.
The perceived meaning of Erebus is “darkness”; the first recorded instance of it was “place of darkness between earth and Hades”. The name Ἔρεβος itself originates from PIE *h1regʷ-es/os- “darkness” (cf. Sanskrit rájas, Gothic riqis, Old Norse røkkr).
According to the Greek oral poet Hesiod‘s Theogony, Erebus is the offspring of Chaos, and brother to Nyx: “From Chaos came forth Erebus and black Night; but of Night were born Aether and Day, whom she conceived and bore from union in love with Erebus.” Hesiod, Theogony (120–125)