Queen Mio
Queen Mio was the identity Mio Kuroki assumed in the Special Act, when she returned and established herself as the Queen of the Dark Kingdom. She was determined to make Mamoru her king, and to that end kidnapped and brainwashed him. When Usagi came to save him, Mio realized that he still loved Usagi, even when under her power. In frustration, Mio transformed into a massive black plant Youma, but was destroyed by the Sailor Senshi when they used Sailor Planet Attack.