Ælfthryth ( - 1000 or 1001, also Alfrida, Elfrida or Elfthryth) 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 Æthelred 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 bad queen and evil stepmother in many medieval histories.