The Fierce Deity is an evil and powerful spirit cursed to be bound to a mask.
The Fierce Deity is a character from LoZ:Majora's Mask. It wields the double-helix sword and is extremely strong and powerful. Whoever wears the mask will become corrupted with it's evil and power. As long as the person wears the mask, the Fierce Deity will be in control of the person's body.
When the Fierce Deity was alive, he had white hair and eyes with no pupil or iris. He had blue and red markings on his face and was very tall and muscular.