According to lore, Mary Worth, also known as Bloody Mary, is an evil ghost who cannot find peace. She is said to appear in a mirror when summoned. The origins of the Mary Worth story may point back to 17th-century Massachusetts. Mary Worth was a young girl whose face was covered in hideous dark-red scars that were either an accident of birth or caused by an injury. The village children teased her and followed her in the streets calling out 'Bloody Mary' over and over again. During a witch scare, Mary was accused of witchcraft and hanged. According to lore, one night, not long after Mary's execution, a group of children decided to play a game of conjuring. They set up a mirror against the wall and began to chant 'Bloody Mary, Bloody Mary'. Suddenly Mary appeared in the mirror. Her face was even more hideous and her hands had turned into claws. She reached through the looking glass to tear the children's faces. Shrieking and screaming, the terrified children ran out of the room. Although Bloody Mary disappeared that day, it is said that her spirit remains, waiting for someone to stand in front of a mirror and chant her name.

In some versions of the legend, the summoner must say 'Bloody Mary, I killed your baby'. In these variants, Bloody Mary is believed to be the spirit of a mother who murdered her children, or a woman who was murdered shortly before or after her wedding. On the other hand, it has been suggested that the story about taunting Bloody Mary about her baby may relate tenuously to folklore about Mary I, Queen of England from 1553 - 1558, who became known as Bloody Mary for her persecution of Protestants. The Queen's life was marked by a number of miscarriages in false pregnancies; if she had succeeded in having a child, this would have established a Roman Catholic succession and the continuance of religious persecution after her death.

The mirror ritual by which Bloody Mary is summoned may also relate to a form of divination involving mirrors and darkness that was once performed on Halloween. Young women were encouraged to walk up a flight of stairs backwards, holding a candle and a hand mirror, in a darkened house. As they gazed into the mirror, they were supposed to be able to catch a glimpse of their future husand's face. There was however, a chance that they would see s skull-face instead, indicating that they were destined to die before they married.