Morgana Pendragon - The main antagonist of Merlin She was once kind-hearted and free spirited. However, she turned evil after being corrupted by Morgause.
Arthur Pendragon - Prince of Camelot; At first arrogant, he bullies his servants, especially his servant Merlin.
Gaius - Court physician and not only a guardian of Merlin, but also his mentor.
Uther Pendragon - Arthur and Morgana's father. Fatally wounded by an assassin trying to kill Arthur.
A witch once friends with Uther. She brings about various ways to get her revenge on him, like poisoning Camelot's water supply and resurrecting his brother-in-law. Killed by Merlin on the Isle of the Blessed. appeared in The Mark of Nimueh, The Poisoned Chalice, Excalibur and Le Mort d'Arthur.
A commoner who desires to become a knight of Camelot. He shares a brief romance with Gwen and becomes one of Merlin's long-term Secret Keepers. He appeared in the first, second, third and fourth series.