Pharaoh 90 emerges as the primary antagonist in the third season, an entity born of dark energy from the Tau Star System in another dimension. He typically manifests as a shadowy form dominated by intense, glowing eyes. This fluid darkness solidifies into a vast, planet-enveloping shape after merging with Mistress 9 and Earth, revealing distinct red pupils. Commanding the Death Busters organization through key subordinates—Professor Tomoe, Kaolinite, Mistress 9, and the Witches 5—his core objective is securing a potent light source equivalent to the Taioron Crystal to sustain his power. He both fears this light's potential to destroy his domain, the Omega Area, and covets its energy to forge a new world. Exploiting a catastrophic lab accident that killed Professor Tomoe's wife and mortally wounded his daughter Hotaru, Pharaoh 90 offered salvation in exchange for possession of their bodies. Tomoe agreed to save Hotaru, allowing Pharaoh 90's influence to permeate them. This enabled his partner, Mistress 9, to embed herself within Hotaru, preparing her as a vessel for his summoning. Summoned to Earth via the Holy Grail and the Silver Crystal's power, Pharaoh 90 merged with Mistress 9 and initiated assimilation with the planet. He sought to terraform Earth into a new homeworld, enveloping it in dark energy and corrupting its surface at the cost of all existing life. His defeat came when Sailor Moon unleashed the Holy Grail's power within him, weakening his core. Sailor Saturn awakened, draining his energy with the Silence Glaive, while Sailor Pluto opened the Door of Space and Time. Severely deteriorated, Pharaoh 90 pleaded to return to his dying homeworld before being expelled alongside Sailor Saturn back to the Tau Nebula dimension. Later continuity identifies Pharaoh 90 retroactively as an incarnation of Chaos, a manifestation of primordial darkness recurring across the series alongside antagonists like Queen Metalia and Death Phantom. His abilities encompass generating dark energy shields, creating Daimon eggs, and drawing power from the Tau Nebula to achieve colossal size. He can also assimilate with planetary bodies, corrupting them globally.