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Jordan Patrick Smith as Ubbe, eldest son of Ragnar and Aslaug (part 2, guest part 1). Elijah O'Sullivan portrays a young Sigurd Snake-in-the-Eye. David Lindström as Sigurd Snake-in-the-Eye, third son of Ragnar and Aslaug (part 2, guest part 1). Stephen Rockett portrays a young Hvitserk. Marco Ilsø as Hvitserk, second son of Ragnar and Aslaug (part 2, guest part 1). James Quinn Markey portrays a young Ivar the Boneless. Alex Høgh as Ivar the Boneless, the fourth son of Ragnar and Aslaug (part 2, guest part 1). Kevin Durand as Harbard, a charismatic wanderer and storyteller (part 1). Jasper Pääkkönen as Halfdan the Black, Harald's violent younger brother.
Peter Franzén as King Harald Finehair, a Viking ambitious to become the first King of Norway. Linus Roache as King Ecbert of Wessex, the ruthless king of Wessex. John Kavanagh as The Seer, the seiðrmann of Kattegat. Lothaire Bluteau as Emperor Charles of West Francia (part 1). Ben Robson as Earl Kalf, a Viking warrior who shares the control of Hedeby with Lagertha (part 1). Alyssa Sutherland as Queen Aslaug, Brynhildr 's daughter and Ragnar's second wife. Nathan O'Toole portrays a young Bjorn Ironside, appearing in Ragnar's visions. Alexander Ludwig as Bjorn Ironside, Ragnar and Lagertha's son, who has a relationship with Torvi. He is on trial for the murder of Athelstan Gustaf Skarsgård as Floki, a gifted shipbuilder and a friend of Ragnar's. Clive Standen as Duke Rollo, a warrior and Ragnar's brother he was granted the title of Duke of Normandy by Emperor Charles. Katheryn Winnick as Queen Lagertha, a shield-maiden and Ragnar's ex-wife she controls the Earldom of Hedeby calling herself Earl Ingstad. Travis Fimmel as King Ragnar Lothbrok, the head of the Earldom of Kattegat who was crowned king after Horik's death. Main article: List of Vikings characters Main