|This section contains non-canon fan theory and speculation.
The theory of the Tetraforce is a relic that canonical Zelda games refer to as the Triforce, but with the missing fourth piece in the center. What sparked this theory was the design of the Hylian Shield from Ocarina of Time. It features the Triforce on the top, a red bird (Link's crimson loftwing from Skyward Sword) in the middle, and a lone triangle seemed to be guarded by the bird on the bottom. This triangle is said to be the missing piece of the Tetraforce. Since the Triforce was left by the three Golden Goddesses; Din, Nayru, and Farore, one triangle for each goddess, some people believed that there was a fourth goddess that left behind the fourth piece. These people believe that this goddess was Hylia, the goddess mentioned in Skyward Sword. The Tetraforce contains the ultimate power, and unlike the Triforce, which grants only one wish for the person who lays their hands upon it, the Tetraforce can grant unlimited wishes. Some people believe that the origin of Fierce Deity from Majora's Mask is that a Hero from long ago (long before the events of Skyward Sword) sought the Triforce. Instead, he came to the Tetraforce and absorbed its power, becoming an uncontrollable, mindless deity that destroyed everything. But the soul of the hero was still in some way aware of his terrible deeds and lived for eternity in despair. However, in all sadness, Nintendo has come out and stated that the Tetraforce is not a real thing in the Zelda Universe. But that does not stop some from speculating.