Lamia

Lamia was a beautiful woman from Libya, whom Zeus often visited and made love to. Each time she gave birth to a child, the jealous Hera would murder Lamia's baby. Eventually, Lamia was so overcome with grief that she was driven insane. Lamia became madly jealous of other mothers who could bear children that Lamia was driven to snatching babies from their cribs at night, before devouring them.

For these hideous acts, Lamia was transformed into an ugly, hideous monster with the ability to remove her eyes when she wanted to sleep.

Lamia was something like a Greek version of a vampire or an ogress, the ancient form of the bogey-woman, where mothers would frighten their children into behaving or else a child-eating monster would come and snatch you, and then devour you.