Vikings: Every Character Based On Real Historical Figures

Rollo is an important historical figure, though he lived after the events seen in the show. He was not Ragnar's brother, instead he was born around 860 AD, decades after Ragnar lived.

He raided in France and got famous for laying siege to Paris in 885 AD. Eventually he was given land around the lower Seine when Charles the Simple agreed to let him have it in return for his protection against other Vikings. Here, Rollo founded the Duchy of Normandy and ruled it from 911 to 927 AD. His descendants stayed in power and conquered parts of Italy and Sicily. He was also the great-great-great grandfather of William the Conqueror who later became William I of England.

He may have married Princess Gisla in real life too, when he was given the land. Though she may have only been five years old at the time.