Elfrida (945-1000, also Aelfthryth or Elfthryth) was the second wife of King Edgar of England.

Her father was Earl Ordgar, Alderman of Devon. Before marrying King Edgar, Elfrida was the wife of Ethelbald, Alderman of the East Angles. Edgar had slain Ethelbald, in order to obtain the hand of his widow; and Elfrida appears to have connived at the crime.

Elfrida was also party to the murder of her step son Edward the Martyr at her residence in Corfe Castle on March 18 978. This was to place her 10-year-old son Ethelred on the throne as King Ethelred II of England.

References

• Chapter XIII - History of the Anglo-Saxons - by Sir Francis Palgrave (1876).