| Katheryn Winnick | Lagertha |
| Alexander Ludwig | Bjorn Lothbrok |
| John Kavanagh | The Seer |
| Peter Franzén | King Harald Finehair |
| Alex Høgh Andersen | Ivar
(as Alex Høgh) |
| Marco Ilsø | Hvitserk |
| Jordan Patrick Smith | Ubbe |
| Jonathan Rhys Meyers | Bishop Heahmund |
| Ferdia Walsh-Peelo | Alfred the Great |
| Georgia Hirst | Torvi |
| Jennie Jacques | Judith |
| Roisin Murphy | Elsewith
(as Róisín Murphy) |
| Ragga Ragnars | Gunnhild |
| Dean Ridge | Magnus |
| Michael Power | Ivar's Bodyguard |
| Alicia Agneson | Freydis |
| Darren Cahill | Aethelred |
| Cian Gallagher | Saxon Servant |
| Ann Skelly | Ethelfled |
| Jim Roche | Saxon Scribe |
| Malcolm Douglas | Cyneheard |
| Tomi May | Jarl Olavsonn |
| Aoife Byrne | Shield Maiden
(uncredited) |
| Katie Castle | Shield Maiden
(uncredited) |
| Joseph Duggan | Viking
(uncredited) |
| Niamh Hogan | Shield Maiden
(uncredited) |
| Michelle O'Flaherty | Shieldmaden
(uncredited) |
| Eimear O'Grady | Shield Maiden
(uncredited) |
| Charles Sans | Viking Elder
(uncredited) |
| Adam Winnick | Viking Warrior
(uncredited) |