Ragnar Lodbrok (Ragnar "Hairy-Breeks", Old Norse: Ragnarr Loðbrók) was a Norse legendary hero from the Viking Age who was thoroughly reshaped in Old Norse poetry and legendary sagas.

The namesake and subject of “Ragnar’s Saga”, and one of the most popular Viking heroes among the Norse themselves, Ragnar was a great Viking commander and the scourge of France and England. A perennial seeker after the Danish throne, he was briefly ‘king’ of both Denmark and a large part of Sweden. A colorful figure, he claimed to be descended from Odin, was linked to two famous shieldmaidens, Lathgertha in the Gesta Danorum, and Queen Aslaug according to the Völsungasaga.

Ivar Ragnarsson (Old Norse: Īvarr; died possibly 873) nicknamed the Boneless (inn beinlausi), was a Viking leader and by reputation also a berserker. By the late 11th century he was known as a son of the powerful Ragnar Lodbrok, ruler of an area probably comprising parts of modern-day Denmark and Sweden.

In the autumn of AD 865, with his brothers Halfdan Ragnarsson (Halfdene) and Ubbe Ragnarsson (Hubba), Ivar led the Great Heathen Army in the invasion of the East Anglian region of England. An accommodation was quickly reached with the East Anglians. The following year, Ivar led his forces north on horseback and easily captured York (which the Danes called Jorvik) from the Northumbrians who were at that time engaged in a civil war.

Ivar and the Danes succeeded in holding York against a vain attempt to relieve the city in AD 867.

Ivar is also attributed with the slaying of St. Edmund of East Anglia in AD 869. The story is first known from Abbo of Fleury's Latin Passion of King Edmund and Ælfric's Old English adaptation thereof. By their accounts, when Edmund refused to become the vassal of a pagan, he was killed in much the same way as Saint Sebastian was martyred. Ivar had Edmund bound to a tree, whereupon Vikings shot arrows into him until he died. According to later accounts, Edmund was shot in the nave of a church.