Sanguisuga

The Sanguisuga are a classification of beasts originating from Et in Opusculo De Telluribus. These beasts come in many forms, but are all characterized by how they exclusively feed off of human blood. They are further classified into two groups:

Nonsexus- Only drink blood of Virgins.

Matrimonium- Only drink the blood of those who are married.

They will not drink the blood of any human outside of their classification's specifications, and will become deathly sick if they do so.