http://en.wikipedia.org/wiki/Ælfthryth,_Queen_of_England

Ælfthryth was the second or third wife of King Edgar of England. Ælfthryth was the first king's wife known to have been crowned and anointed as Queen of the Kingdom of England. Mother of King Ethelred the Unready, she was a powerful political figure. She was linked to the murder of her stepson King Edward the Martyr and appeared as a stereotypical bad Queen and evil stepmother in many medieval histories.