Queen Beryl

Queen Beryl was on the overall, in charge of the whole operation for collecting human energy and finding the Holy Silver Crystal for the resurrection of Queen Metallia, ruler of the Dark Kingdom. Merciless and prone to flights of rage, Queen Beryl is responsible for the deaths of two of her own generals, Jadeite and Zoisite.
Queen Beryl, who is a powerful sorceress, is also very much infatuated with Endymion / Tuxedo Mask. She holds a personal vendetta against Princess Serenity / Sailor Moon for being the object of his love.

Beryl succeeded in brainwashing Tuxedo Mask into assuming the role of Commander Endymion for the Dark Kingdom, but Endymion eventually turned against her after regaining his memory.

In the end, Beryl's body was taken over by Queen Metallia for the final confrontation with the Moon Princess Serenity.