In the series Vikings, Ragnar’s brother Rollo is arguably a mere secondary character in the Lothbrok family. In real life, however, Rollo's life has center stage.
Rollo of Normandy was also known as Rolf, Hrolf or Rou; in French, Rollon. He was sometimes called Robert and was also known as Rollo the Viking. It was said Rollo was too tall to ride a horse without his feet reaching the ground, and it was for this reason he was known as Rollo the Walker or Rollo the Gangler or Ganger.
Rollo of Normandy was an extremely important historic character, and was responsible for the creation of the duchy of Normandy in France. Although Rollo is sometimes called "the first Duke of Normandy," this is somewhat misleading, as he never held the title of "duke" during his lifetime.
His descendants became known as the Normans, lending their name to the region of Normandy. He is also the great-great-great-grandfather of William the Conqueror , also known as William I of England, which means that Rollo is one of the ancestors of the present-day British royal family. He was born in 846 and died in 930, and he was not Ragnar’s brother, an easy fact to understand since the siege of Paris led by Ragnar and depicted on the season four of the Series historically happened on 845, one year before Rollo was born.
In his early life, Rollo left Norway to embark on raiding expeditions to England, Scotland, and Flanders, eventually arriving in France and settling along the Seine, besieging Paris in 885-886. Charles III (the Simple) of France was able to hold Rollo off for a while, but he eventually negotiated a treaty to stop him. The treaty of Saint-Clair-sur-Epte gave Rollo part of Nuestria in return for his agreement that he and his fellow Vikings would stop pillaging any further in France. It is controversial if he did or not convert to Christianity, with some sources claiming he was baptized in 912, while other sources claim that Rollo "died a pagan."
Because the region was settled by Northmen or "Normans," the territory took on the name "Normandy," and Rouen became its capital. Before Rollo died he turned over the governance of the duchy to his son, William I also known as the Longsword, who continued a mighty dynasty, fathering Richard the Fearless, who fathered Richard the Good, who fathered Robert I, who fathered William the Conqueror.