Aethelred the Unready was an English king who ruled from 966 to 1016. He is often remembered for his struggles against Viking invasions during his reign. His nickname, "Unready," comes from the Old English word "unræd," meaning "bad counsel," reflecting his difficulties in making effective decisions. Despite his challenges, Aethelred attempted various strategies to defend his kingdom, including paying off the Vikings with large sums of money known as Danegeld. His reign ended with the rise of Cnut, a Danish king who eventually conquered England, marking a significant shift in English history.