Humber the Hun was a legendary king of the Nordic "Huns" as accounted by Geoffrey of Monmouth. According to Geoffrey, following the division of Britain amongst Locrinus, Kamber, and Albanactus, Humber invaded Albany and killed Albanactus in open battle. The remaining people fled south where Locrinus allied with Kamber and defeated Humber near a river. Humber drowned in that river, which was thereafter known as the Humber, one of the main rivers of England.
When Locrinus raided Humber's ships after his death, he found Estrildis, the daughter of the King of Germany there.
References
Humber the Hun Wikipedia(Text) CC BY-SA