Troll (Catrina)

Catrina was a troll who attempted to take over Camelot by marrying Uther Pendragon. She was later killed by Arthur Pendragon with the help of his servant, Merlin.

Biography
Catrina (with the help of her servant Jonas) created a potion which allowed her to take on the appearance of the Lady Catrina. She later bluffed her way into the palace using the seal of the House of Tregor. She placed a love charm of Uther and he quickly began bending to her every word. When Merlin begins to suspect her, she orders Jonas to trap him before her marriage to Uther, which went on without a hitch.

Upon realising that Merlin had escaped, Catrina claimed he'd stolen her seal, prompting Uther to order his death. She also made Uther enforce a new tax on the people to satisfy her greed, much to Arthur's dismay. When Arthur released a man who didn't pay the tax, she used this to have Uther believe his son was too weak to rule and have him make her the heir to the throne. However, during her ceremony her troll form began to emerge due to Merlin switching her real potion for a fake. As she tried to escape, she transformed completely, much to the shock of everyone except Uther, who didn't notice any change.

However, her plan ultimately failed when Gaius and Merlin staged Arthur's death, bringing Uther to tears of true remorse. These tears broke the enchantment as he saw Catrina for what she truly was. Despite all attempts to prevent Arthur from drinking the antidote, he recovered from his state of living death and stabbed her.