Three main characters who died in previous seasons briefly appear played by body doubles: Sigurd's corpse is briefly shown in 'The Fisher King', King Ecbert appears in 'The Fisher King' as a corpse and in 'Baldur' as a cloaked figure, and Athelstan is seen as a cloaked figure in 'The Departed'. Clive Standen as Duke Rollo, a warrior and Ragnar's brother he was granted the title of Duke of Normandy by Emperor Charles.John Kavanagh as The Seer, the seiðrmann of Kattegat.Jonathan Rhys Meyers as Bishop Heahmund, a Christian warrior priest.Jordan Patrick Smith as Ubbe, eldest son of Ragnar and Aslaug.Marco Ilsø as Hvitserk, second son of Ragnar and Aslaug.Alex Høgh as King Ivar the Boneless, fourth son of Ragnar and Aslaug he becomes king of Kattegat.Moe Dunford as King Aethelwulf of Wessex (part 1).Jasper Pääkkönen as Halfdan the Black, Harald's violent younger brother (part 1).Peter Franzén as King Harald Finehair, a Viking ambitious to become the first King of Norway.Alexander Ludwig as Bjorn Ironside, Ragnar and Lagertha's son and Torvi's husband.Gustaf Skarsgård as Floki, a gifted shipbuilder.Katheryn Winnick as Queen Lagertha, a shield-maiden and Ragnar's ex-wife she is the queen of Kattegat.Main article: List of Vikings characters Main