Erzebet Bathory in The Blood Confession, by Alisa M. LibbyRead about the other entries on the list.
In the late 16th century, a vain countess began to fear that one day her looks would fade. She noticed a lot of her maids were gorgeous, and got the idea that maybe their blood would keep her looking forever young. As with any slippery slope, it started with simple bloodletting akin to “medical practices” of yore (albeit with cosmetic intentions, not health ones), and then oops! It became serial murders. This is a chilling fictionalized account that will make you think the Evil Queen from Snow White was really not that bad.