Mistress 9 is one of the major villains of Sailor Moon S. She is also known as the Sovereign of Silence. She controls the Bureau of Bad Behavior, including Doctor Tomoe, and is second only to Pharaoh 90.
Her first appearance was in Episode 22, The Purity Chalice, though she is never referred to as Mistress 9 until she awakens.
She would often take control of Hotaru. After the death of Eugeal, and Sailor Moon got the Purity Chalice, Mistress 9 commanded the Heart Snatchers to find Pure Hearts to feed to her. She never did get to eat any, however, until Episode 34, Wake Up Call, when Kaorinite captured Sailor Mini Moon. After eating her Pure Heart, Mistress 9 awakened in her true form. She killed Kaorinite with a bolt of lightning, saying that she had served her purpose and was not needed anymore.
Mistress 9 pulled Sailor Moon into the school. After finishing off Germatoid, Sailor Uranus and Sailor Neptune attempted to kill Mistress 9 (and Hotaru with her) but Sailor Moon protected her. By pretending to be Hotaru, she tricked Sailor Moon and the un-possessed Doctor Tomoe to give the Purity Chalice to her, and she used it to awaken Pharaoh 90. However, having fulfilled her objective of using the Purity Chalice to awaken him, Mistress 9 is betrayed by Pharaoh 90, who no longer has any use for her, and attempts to kill her. However, his attacks only weaken her while Sailor Moon took the brunt of the attacks.
As a result of the disbelief Mistress 9 suffered in Pharaoh 90 trying to eliminate her, Hotaru was able to fight Mistress 9 from within, and, with memories of her father and Rini, along with Mistress 9 having been weakened by Pharaoh 90 so she could not fight off Hotaru this time, overpowered her, completely destroying her while Hotaru became Sailor Saturn.
Mistress 9 shoots bolts of lightning, and can extend her extremely long hair to wrap around her enemies. She can also reach through portals to anywhere else using a shadowy hand.
Voiced by Jennifer Gould