Kings and Queens of the British Isles: AEthelred the Unready

With an unfortunate addition to his name, which in Old English means "Poorly advised", AEthelred the Unready, one of the last of the Saxon Kings (Reigned 978-1016), came to the throne in damaging circumstances, his elder half brother, the previous King, being murdered probably on the orders of AEthelred's mother, who ruled as regent until AEthelred came of age.
AEthelred's reign seems to have been spent mistreating his subjects and allowing enough discord to happen, leaving them vulnerable to repeated Danish attacks, culminating in invasion by Sweyn Forkbeard, and once that had been dealt with, war with Sweyn's son, Canute, who eventually became King of England a few months after AEthelred's death
Remembered with some disparagement, his reign nonetheless signalled the start of changes from the Saxon dynasty, to a brief Viking dynasty, returning to the Saxon dynasty, before the Battle of Hastings some fifty years after AEthelred's death