- "Could this mask's dark powers be as bad as Majora?"
- — In-game description
The Fierce Deity's Mask (Japanese: 鬼神の仮面 Kijin no Kamen lit. Devil God's Mask) is the final transformation mask that Link can obtain in The Legend of Zelda: Majora's Mask. The mask allows Link to transform into a mighty god, Fierce Deity. Because of this, it can only be worn during boss battles, barring glitches. Nobuyuki Hiyama, the voice actor of adult Link in The Legend of Zelda: Ocarina of Time, also voices Fierce Deity Link. The model for Link as Fierce Deity is exactly the same one used for Link as an adult in Ocarina of Time, only with a different design and a different sword. However, the Fierce Deity model is much taller than Adult Link, possibly eight feet (2.4 m) at the least, and is almost the same height as Odolwa; this size seems to be more noticeable when outside of boss rooms through the use of glitches.
Link can obtain the Fierce Deity's Mask by trading the twenty non-transformation masks to the four Lunar Children wearing the Boss Remains at the Moon. Ironically, Link obtains the mask from the child wearing Majora's Mask just prior to the final battle with Majora. The child gives him the Fierce Deity's Mask so that the two of them can play "good guys against bad guys" together. Fierce Deity's Mask is not required to defeat Majora, but it makes the battle much easier.
Many believe that Fierce Deity is Majora's nemesis and that Majora gives Link the mask in order to defeat the hero as well as the spirit inhabiting the mask at the same time.
It is also possible that the Fierce Deity is a different incarnation of Link as the Fierce Deity's Mask bears an identical resemblence to adult Link from The Legend of Zelda: Ocarina of Time whether the mask is worn or not worn.
Like the spirits in the other transformation masks, the Fierce Deity in fact might have been alive at one time. When Link speaks to Pamela's Father while wearing the Fierce Deity's Mask, Pamela's father infamously says, "Oh! Mmmmm! My Ghost Radar is reacting fiercely. But...This is minutely different from its usual response. This is a verrrry intriguing response!"
Another theory is that the Fierce Deity may have been worshipped by some people in Termina. In the Majora's Mask manga, when Tatl is astonished by the form that Link had taken, Kafei and Anju are very well aware of who the Fierce Deity is.