Series two regular cast members include Colin Morgan, Bradley James, Katie McGrath, Angel Coulby, Anthony Head, Richard Wilson, and John Hurt as the voice of the Great Dragon.

BBC renewed the show for the third series which premiered on 11 September 2010.

Merlin continues to serve Prince Arthur while concealing his magical abilities in a kingdom where they are outlawed.

New adventures arise in the form of trolls, witchfinders, Druids, the return of an old friend and Dragonlords.

While Merlin continues to ensure Arthur grows into the Once and Future King and Arthur and Gwen start to see each other in a new light, a new threat prepares to come to Camelot and a friend will have to make a choice that will alter the legend forever.