Chaos (or "Khaos") was the original void and orderless state of the universe, and sometimes considered a primordial deity in Greek mythology.
He or She (Chaos is sometimes poetically female) is the parent of Tartarus (Abyss), Eros (Love), Erebus (Darkness), Nyx (Night) and Gaia (Mother Earth). Gaia then brought forth Ouranos, the starry heavens and her male equal, to be her companion. With him she gave birth to the Titans and some of the other primordial deities. Nyx brought forth Aether (Light), Hemera (Day), Moros (Doom), Oneiroi (Dreams), Nemesis (Retribution), Momus (Blame), Philotes (Affection), Geras (Aging), Thanatos (Death), Hypnos (Sleep), Eris (Strife), Apate (Deceit), Oizys (Distress), the Sisters of Fate and the Keres.
Chaos can be seen as the first of all the gods and the creator of reality - Chaos is also considered the god that will destroy existence and return everything to the chaos from whence it came.