The third season of the historical drama television series Vikings premiered on February 19, 2015 on History in Canada, and concluded on April 23, 2015, consisting of ten episodes. The series broadly follows the exploits of the legendary Viking chieftain Ragnar Lothbrok and his crew, and later those of his sons. The first season of the series begins at the start of the Viking Age, marked by the Lindisfarne raid in 793. The third season follows the development of Ragnar's family, and the Vikings as they become more entwined in English mingling affairs, and also begin to raid farther afield. Cast Main Travis Fimmel as King Ragnar Lothbrok, the head of the Viking earldom of Kattegat who became king after Horik's death Katheryn Winnick as Lagertha, a shield-maiden and Ragnar's ex-wife; she controls the Earldom of Hedeby calling herself Earl Ingstad. Clive Standen as Rollo, a warrior and Ragnar's brother Jessalyn Gilsig as Siggy, widow of Earl Haraldson and Rollo's lover Gustaf Skarsgård as Floki, a gifted shipbuilder and friend of Ragnar's George Blagden as Athelstan, an Anglo-Saxon monk from Northumbria who is torn between the Viking gods and the Christian God; he is a friend and adviser to both King Ragnar and King Ecbert. Alexander Ludwig as Bjorn Ironside, Ragnar and Lagertha's son, who has fallen in love with the shield-maiden Þórunn Alyssa Sutherland as Queen Aslaug, Brynhildrs daughter and Ragnar's second wife Ben Robson as Kalf, the ruler of Hedeby in the absence of Lagertha Linus Roache as the ruthless King Ecbert of Wessex Kevin Durand as Harbard, a wanderer Lothaire Bluteau as Emperor Charles of West Francia Recurring Amy Bailey as Princess/Queen Kwenthrith of Mercia Moe Dunford as Prince Aethelwulf of Wessex, son of King Ecbert Maude Hirst as Helga, Floki's wife Gaia Weiss as Þórunn (/θorunn/), a freed slave and Björn's love interest Jefferson Hall as Torstein, one of Ragnar's warriors Jennie Jacques as Princess Judith of Northumbria, daughter of King Ælle, wedded to Aethelwulf John Kavanagh as the Seer, a seiðmann Steve Wall as Einar, a relative of late Jarl Sigvard and an opponent of Lagertha in Hedeby Cathal O'Hallin as Hvitserk, second son of Ragnar and Aslaug Cormac Melia as Ubbe, eldest son of Ragnar and Aslaug Philip O'Sullivan as Bishop Edmund, serving at the court of King Ecbert Aaron Monaghan as Prince Burgred, the younger brother of Princess Kwenthrith Edvin Endre as Erlendur,