Chaos was the final villain Eternal [Sailor Moon](https://anilist.co/character/2030/Usagi-Tsukino) faced. It was said to be the source of all evil in the galaxy and influences others despite not having a physical form for itself. Even when defeated, it is not fully destroyed and is sure to eventually return.
In the manga, Chaos is a being that was trapped in the Galaxy Cauldron and missed out on becoming a star. It sends out incarnations in the form of Sailor Moon's major enemies, and eventually uses [Sailor Galaxia](https://anilist.co/character/4900/Sailor-Galaxia) to steal Sailor Crystals so it can free itself and rule the galaxy. Chaos does not appear explicitly in the anime, but is a force which possesses Sailor Galaxia.
