Fredegonda
From BiblePortal Wikipedia
Fredegonda [1]
Wife of Chilpéric I. of Neustria; a woman of low birth, but of great beauty and insatiable ambition, who scrupled at no crime to attain her end; made away with Galswintha, Chilpéric's second wife, and superseded her on the throne; slew Siegbert, who had been sent to avenge Galswintha's death, and imprisoned Brunhilda, her sister, of Austrasia, and finally assassinated her husband and governed Neustria in the name of her son, Clotaire II. (543-597).