Ælfthryth (also Alfrida, Elfrida or Elfthryth; died 17 November 999, 1000 or 1001) was Queen of the English from her marriage to King Edgar in 964 or 965 until Edgar's death in 975. She was a leading figure in the regency during the minority of her son King Æthelred the Unready between 978 and 984.

Ælfthryth was the first wife of an English king known to have