Pharaoh 90 is a universal entity of pure evil from an unknown part of the cosmos, the power source of the impending doom and Silence and Daimons, and the true antagonist of Sailor Moon S. It is one true mastermind of the Death Busters; especially Mistress 9.
Pharaoh 90 was the one who provided Professor Tomoe with Mistress 9's Daimon pod, and had the demon Germatoid possess Tomoe when he and his six-year old daughter Hotaru Tomoe were caught in a lab explosion. Pharaoh 90's plan was for Professor Tomoe to collect Pure Heart Crystals to fully revitalize and awaken Mistress 9, the Messiah of Silence, and for her to obtain the Holy Grail so she could summon it. Once this came to pass, Pharaoh 90 began using the Silence to destroy everyone and everything in existence.
After she erases Mistress 9, Hotaru transforms into Sailor Saturn, uses her power to enter Pharaoh 90 and destroy it by attacking his core. Sailor Moon, frustrated because she was unable to stop Sailor Saturn from sacrificing her own life to destroy Pharaoh 90 once and for all, was able to transform into Super Sailor Moon by producing a Pure Heart that surpasses the Holy Grail. With the power of the other Sailor Senshi and the power of her Pure Heart, she entered Pharaoh 90 at the last minute, joining Saturn's strongest destructive attack on the evil entity, resulting in its annihilation.
- Pharaoh 90 has the shortest final battle with Super Sailor Moon, which mainly consists of her transforming, entering him, and destroying him alongside a newly awakened Sailor Saturn.
- Pharaoh 90 had no dialogue during its appearance in the anime.
- In the original dub, however, it did have one line, when Sailor Saturn was inside him: Who's there? Where are you?
- It is the last of the true/final antagonists to be destroyed, as Queen Nehelenia is resealed inside her mirror and later turned into a child and leaves Earth and Chaos returned to everyone's hearts after Princess Serenity healed Galaxia.
- Pharaoh 90 is the second and final true antagonist to use and manipulate the main antagonist into willingly working for and obeying it.