Erebus

Erebus, the primordial darkness and the darkness of the Underworld, was the offspring of Chaos along with his sister Nyx (Night). Erebus is also called a region of the Underworld and is sometimes used to refer to the Underworld. The children of Erebus sometimes include the Aether, Hemera (day), the Moirai (Fates), the Hesperides (guardians of the golden apples), Hypnos (Sleep), Geras (Old Age), Thanatos (Death), Charon (the ferryman of the dead), and Styx.

Relevant Passage From Hesiod's Theogony on Erebus

(ll. 116-138) Verily at the first Chaos came to be, but next wide-bosomed Earth, the ever-sure foundations of all (4) the deathless ones who hold the peaks of snowy Olympus, and dim Tartarus in the depth of the wide-pathed Earth, and Eros (Love), fairest among the deathless gods, who unnerves the limbs and overcomes the mind and wise counsels of all gods and all men within them. From Chaos came forth Erebus and black Night; but of Night were born Aether (5) and Day, whom she conceived and bare from union in love with Erebus.