Ethelred II, or Aethelred II (968?–1016), king of England 978–1016. He was called Ethelred the Unready, meaning “without counsel” or “resourceless.” Ethelred became king as a child after the murder of his half-brother, Edward the Martyr. Early in his reign Ethelred began a policy of buying off Norwegian and Danish invaders. In 1002 he massacred the Danes living in England, a senseless act that only increased the fury of Danish invasions. In 1013 King Sweyn of Denmark won control of most of England, forcing Ethelred to flee. Ethelred returned after Sweyn's death the next year, ousted Sweyn's son Knut (Canute), and held the throne until his death in 1016.

Ethelred was succeeded by his son Edmund II. Edmund was succeeded by Knut, who married Ethelred's widow, Emma. Another of Ethelred's sons, Edward the Confessor, became king on the death of Knut's son Hardecanute.