Lamia

Somewhat vampirical, this was a female monster who was thought to steal children and drink their blood. She was thought to have a woman's head and breasts, but a serpent's body. In some accounts she was one of Zeus' lovers who bore him children. Hera, in fits of jealousy, caused each child that was born to die. In despair, Lamia became a monster jealous of mothers more fortunate than herself. So she devoured their children. Female spirits which attached themselves to children in order to suck their blood were also called Lamiae.