Edmund the Magnificent
Edmund (later named the Magnificent) was the son of Edward the Elder by his third wife, Edgiva. He was born in 921CE, and first came to prominence at 16, when he accompanied his elder half-brother, Athelstan (who had succeeded their father on the English throne in 924), to war aganist the Norsemen of North England, at the battle of Brunanburgh. When Athelstan died, in 939, Edmund succeed to the throne, the first king to be able to claim sovreignty over "all" of modern England, being ruler of Mercia, Wessex and of the North.
When a Norseman, Olaf or Anlaf Guthfirthson, seized York and declared himself its king the following year, Edmund marched North, beseiged the city, and finally, with the help of the Archbishops of Canterbury and York, settled a treaty. In 941 Olaf/Anlaf had a terminal accident while trying to raid Northumbria, Edmind marched north again, and removed the East Midlands area from the sway of Olaf Sigtryggson, who was trying to hold on to York, as well as blocking an advance from Wales by Idwal of Gwynedd. In 944CE Edmund marched on York itselfm expelled Sigtryggson, and, for good measure, his rival Ragnall Guthfirthson. And in the subseqeutn year he attacked Strathclyde, killed its king, and handed his kingdom to the Scots Malcolm I, and recognised Northumbria as the border between their kingdoms, thereby obtaining Malcolm's favour for life.
Edmund married twice, to (later Saint) Aelfgith, who bore him two sons, Eadwig and Edgar, before her death in 944CE, and Ethelflead, daughter of Aelfgar, Ealdorman of Wilthshire, who gave him no children. Edmund died in 946, stabbed in a scuffle when an outlaw (Leofa) managed to infiltrate a Court in Gloucestershire. He was buried at Glastonbury, and succeeded by Eadred, his younger brother.
His attribution as "the Magnifient" may have been an attempt at translating into Latin a Saxon epithet meaning "Doer of Deeds".