There is the strix, a kind of ancient Roman vampire -- only more monstrous in that it preys on children.
My interest in the strix was inspired by a 2005 thread that I'd found, in which Ursus wrote: So I assume this is the root of the word "stregheria," the word for supposedly Medieval Italian witchcraft? (The Italian word strega, meaning "witch," is derived from the Latin strix.)
One of my favorite ancient Romans, Ovid, describes the striges in Book XI of his Fasti (in the section for the Kalends of June, translation by James G. Frazer):
"There are greedy birds, not those that cheated Phineus' maw of its repast, though from those they are descended. Big is their head, goggle their eyes, their beaks are formed for rapine, their feathers blotched with grey, their claws fitted with hooks. They fly by night and attack nurseless children, and defile their bodies, snatched from their cradles. They are said to rend the flesh of sucklings with their beaks, and their throats are full of the blood which they have drunk. Screech-owl is their name, but the reason of the name is that they are wont to screech horribly by night."
Ovid then goes on to relate an incident in which a child had been attacked by the striges, and the charm, sacrifice, and incantation used to protect the child against further attack:
"Whether, therefore, they are born birds, or are made such by enchantment and are nothing but beldames transformed into fowls by a Marsian spell, they came into the chambers of Proca. In the chambers Proca, a child five days old, was a fresh prey for the birds. They sucked his infant breast with greedy tongues, and the poor child squalled and craved help. Alarmed by the cry of her fosterling, the nurse ran to him and found his cheeks scored by their rigid claws. What was she to do? The colour of the child's face was like the common hue of late leaves nipped by an early frost. She went to Crana