She’s no Bathory, but still an interesting story.
Eadburh (also Eadburg, Edburga) was the daughter of King Offa of Mercia and Queen Cynethryth. She became queen by her marriage to King Beorhtric of Wessex in 789.
It is said that she “accidentally” poisoned her husband and fled to Francia- there, Charlemagne asked her if she’d like to marry him, or his son. When chose his son (because of his youth) Charlemagne said “because you didn’t choose me, you shall have neither.” (or something along those lines.)
Instead- she became the abbess of a convent.
However, even at the abbey she managed to find trouble and was accused of “fornicating with an English exile”. So… she was then expelled from the abbey. But there’s more.
According to some creepy welsh monk named John Asser:
“This Queen Edburga was a handsome murderess, who poisoned people when they offended her. One day she mixed a cup of poison for a certain noble belonging to the court, but her husband drank of it, too, by mistake, and died. Upon this, the people revolted in great crowds, and running to the palace, and thundering at the gates, cried, “Down with the wicked queen who poisons men!” They drove her out of the country, and abolished the title she had disgraced. When years passed away, some travellers came home from Italy, and said that in the town of Pavia they had been a ragged beggar woman – who had once been handsome, but was then shriveled, bent, and yellow – wandering about the streets, crying for bread; and that this beggar woman; and that this beggar woman was the poisoning English queen. It was, indeed, Edburga; and so she died, without a shelter for her wretched head.”
She actually goes down in history as a serial killer. I think this was all rubbish- a politically motivated smear campaign. But you can decide for yourself. Read a more in-depth article on her life here: http://thefreelancehistorywriter.com/2013/10/11/eadburh-queen-of-the-west-saxons/