Travis Fimmel Ragnar Lothbrok Actor Gabriel Byrne Earl Haraldson Actor Gustaf Skarsgård Floki Actor Katheryn Winnick Lagertha Actor Jessalyn Gilsig Siggy Actor George Blagden Athelstan Actor Clive Standen Rollo Actor Ivan Kaye King Aelle Guest Star 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