Æðelræd

'Ethelred the Unready is a figure of fun in English history. It is now considered old-fashioned to classify monarchs as good kings or bad kings, but by almost any measure Ethelred was a bad one. In 978 he inherited the rich and respected kingdom of Engla-lond that had been pulled together by Aethelflaed, Edward, Athelstan and the other descendants of his great-great-grandfather Alfred. By 1016 Ethelred had lost it all, from Northumbria down to Cornwall, in the course of a reign that made him a byword for folly, low cunning and incompetence.
'Perhaps the one sphere in which he deserves some sympathy is his unfortunate nickname, a mistranslation of the gibe made after his death by chroniclers who dubbed him Ethelred 'Unred'. In fact, unred was an Old English word that meant "ill-advised", and it made a rather clever pun on the meaning of Ethelred's name, "of noble counsel", rendering Ethelred Unred "the well-advised, ill-advised".'
-Robert Lacey

"Ethelred the Unready" sounds hilarious, but in fact conceals an Anglo-Saxon pun: he wasn't "unready" in the sense of "always late" or "poorly prepared", but "un-advised" or "poorly advised". This gave him the name + title of Aethelraed Unraed, Wise Advice Bad Advice.