Katheryn Winnick Lagertha Actor Moe Dunford Aethelwulf Actor Josefin Asplund Astrid Actor Alexander Ludwig Bjorn Actor Gustaf Skarsgård Floki Actor Jonathan Rhys-Meyers Bishop Heahmund Actor Jasper Pääkkönen Halfdan the Black Actor Marco Ilsø Hvitserk Actor Alex Høgh Andersen Ivar the Boneless Actor Jennie Jacques Judith Actor Peter Franzén King Harold Finehair Actor Clive Standen Rollo Actor Jordan Smith Ubbe Actor John Kavanagh The Seer Actor Michael Hirst Executive Producer Morgan O'Sullivan Executive Producer John Weber Executive Producer Sherry Marsh Executive Producer Alan Gasmer Executive Producer James Flynn Executive Producer Sheila Hockin Executive Producer