Bloody Mary is a spirit who is said to kill anyone who chants her name numerous times in front of a mirror around midnight. This ghost was based on the half-sister of Elizabeth I, who tried to steal the throne from her sister. She earned the title "Bloody" Mary because she killed hundreds of people who followed Anglicanism which is a different type of Church that allows married couples to divorce. Her father, King Henry VIII created Anglicanism so he could divorce his wife in favor of another woman. This was one of the many ways he remarried. The nursery rhyme "Mary, Mary, quite contrary" is NOT based on her life.
Protection: Surround yourself in salt.
How to kill: Show her a mirror (not proven)
Bloody Mary is one of the world's most widely recognized monsters.