Lilith

Lilith is a figure who crops up throughout folklore in various incarnations. She is purported to be the origin of the vampire curse, it being her blood that taints the original vampire in any family. Many have sought out her favor, only to disappear during the journey. It is rumored that she will grant a boon to whoever proves themselves worthy.

Needless to say, should you chose to fight her, it may be hard.

Some books mention an unnamed woman.