I would say Vikings were one of the most influential people in history. They were among the first to promote the idea of all men are created equal (Rollo landing in Normandy), opened up river trade routes, made Europe better protect their vulnerable coastal/river cities, established Russia (the Rus Vikings), founded Dublin as a major trading city, discovered Americas by crossing the Atlantic, etc...
Most influential man? I would go with Buddha myself. I respect most of what they say Jesus stood for but the sad part is that most Christians don't follow his teachings.