The Deathbusters - the head villains.
Professor Souichi Tomoe
Professor Tomoe was head of research at the university he worked at,and one day in his laboratory he was showing an experiment to his colleagues along with his daughter Hotaru when something went terribly wrong with the experiment. All of the spectators died along with Hotaru. The sole survivor was Professor Tomoe himself. A Daimon Master approached the professor some time later, suggesting that, in return for the professor's soul, Hotaru could be given life again. Professor Tomoe agreed, and he bacame head of the Deathbusters. Later, when Sailors Neptune and Uranus summoned their talismans, the evil in Professor Tomoe was released.
Kaolinite
Kaolinite was the first of the Deathbusters to quest for the heart crystals . She was not a Witches five member, and was killed by the Inner Senshi and Sailor Uranus atop Tokyo Tower. But she came back as Kaori, housekeeper and lab assistant to Professor Tomoe, and a cruel tyrant to Hotaru. She fed Hotaru Chibi-usa's talisman or heart crystal. When Prof. Tomoe congratulated Kaolinite for finding a pure heart, Mistress Nine killed Kaolinite with a blast. (By the way, in the episode of her first death, she used her hair as a weapon, very much like Mistress Nine)
Mistress Nine
Mistress Nine's only goal was to summon the Master Pharoah Ninety. She possesed Hotaru after Kaolinite fed Hotaru Chibi-usa's heart crystal. She died when Hotaru repossesed her body and became Sailor Saturn. She had long, flowing hair that she uses as a weapon.