"The Sailor Scout of Destruction" from the Super Sailor Moon series. She posessed powers capable of destroying a planet and was the owner of a scepter called the Silence Glaive. However, she had to be careful. If she ever used her powers to their ultimate extent, meaning to kill and destroy, she would die as well. She also was one of two creatures living inside the innocent Hotaru Tomoh.
Even though Sailor Moon is the leader of the group, Sailor Saturn carries the ultimate power of death.