Prince Endymion
Prince Endymion was the evil side of Mamoru. He became evil because he was captured by Queen Beryl and brainwashed. Sailormoon had healed him once, but was immediately taken back to be reprogrammed. Zoisite didn't care for him, and killed him in jealousy. Queen Beryl was upset about this and killed Zoisite. Prince Endymion was once again brain washed only this time it was pretty permanent. Through the season it was interesting to see that Prince Endymion would save Sailormoon a couple times even though he swore he was evil.
In the final battle between him and Sailormoon, he really lets her have it. He chokes her, kicks her, electrocutes her, as well as other things. Queen Beryl ordered him to cut off Sailormoon's head. In a last effort Sailormoon tried to heal him but it didn't phase him. He jumped up and knocked her down. He raised his sword about to do it, but Sailormoon used her tiara and blasted him down. She took out her locket, and asked him to come back. He touched the locket and he was healed. Queen beryl upset about this, threw a black crystal dagger at them. Prince Endymion then shot a rose through it and the shards stabbed at his body as he shielded Sailormoon. Queen Beryl disappeared and Prince Endymion died.