Grettir is a mysterious dwarf Warlock with many unknown powers.
Grettir was a sorcerer who guarded the bridge leading the way to The Fisher King's kingdom and anticipated the arrival of Arthur Pendragon, Merlin, and Gwaine. He desired the Fisher King's kingdom to be returned to its former glory. When Arthur first arrived alone, Grettir met him on the bridge and knew him at once, referring to him as Courage. He also told Arthur that he would need Strength and Magic to complete his quest, though unbeknownst to Arthur, this meant Gwaine and Merlin respectively.
When Arthur crossed the bridge on his quest for the Trident, Grettir noticed the Phoenix Eye on his wrist and was evidently aware of its true purpose. Arthur insisted that it was a gift of good fortune from someone someone very dear to him, but Grettir did not enlighten him as to its detrimental effect and simply laughed at this, before disappearing.
Later on, Grettir met Merlin, identifying him as "Magic", before telling him that the quest was actually his, rather than Arthur's. Gwaine appears shortly thereafter, with which Grettir remarked that the trio is complete. Upon seeing Grettir, Gwaine took out his sword and pointed at Grettir, asking him who he was. In response, Grettir turned the sword into a flower until Gwaine had reached the other side of the bridge, justifying it by saying that he meant no harm and would expect Gwaine to mean no harm in return. (The Eye of the Phoenix).
- Warwick Davis, the actor who portrays Grettir, has also had roles in Star Wars, Harry Potter, 'The Chronicles of Narnia: Prince Caspian, 'Willow, The Hitchhiker's Guide to the Galaxy, four of the Leprechaun films, and the comedy series Extras. He also has his own series called Life's Too Short.
- It is never explicitly mentioned that Grettir is a dwarf, he's just referred to as one based on his size.
- A deleted scene from The Eye of the Phoenix has Arthur's map disintegrating spontaneously when he is looking at it, while Grettir can be heard laughing mischievously in the background.