Actor Liam Cunningham has been announced as joining the cast of BBC One fantasy series Merlin – guest stars from series four to return.

First Look: Liam Cunningham on the set of Merlin

The actor who is currently appearing in the second series of Sky Atlantic’s Game of Thrones, will appear in series five in a guest role.

The BBC also confirmed returning guest stars to Digital Spy: “We can confirm that… Liam Cunningham is going to appear in series five, along with returning guest stars Lindsay Duncan (Queen Annis) and Janet Montgomery (Princess Mithian),” the BBC said.

Merlin will return to BBC One later this year.

Behind the Scenes –  Colin Morgan on set