William the conqueror [1] is a direct descendant of a viking, Rollo, who made a deal with the king of France: territory in exchange for protection against the
other vikings. The name of this territory is relatively well-known for other historical reasons: Normandy. The conquest of England by William "the conqueror", duke of Normandy, is why the English language has a significant number of French origin.
[1] https://en.wikipedia.org/wiki/William_the_conqueror