Bakene

Bakene is a cat-like Youma who is one of the Seven Shadows. He was trapped inside a Rainbow Crystal and reborn inside a cat named Hercules. In Episode 27, Kitty Chaos, Zoycite extracted the crystal from him and transformed him into the beastly Bakene, Champion of the Negaverse. It didn't attack much especially since it remembered Luna. The seventh Shadow was killed when Hercules was healed by Sailor Moon using her Moon Healing Activation.