Traveling Warrior

The is a character that appears in the original side story of the Majora's Mask manga. He is a hero from a faraway land who came to Termina and met Majora ten thousand years prior to the events of Ocarina of Time and Majora's Mask.

History
An unknown warrior appears before a large, shaggy creature known as Majora. The creature, believing that the warrior wants his magical armor so that he may have his heart's desire, intends to kill the warrior. However, the warrior produces a drum and begins playing it. Entranced by the music, Majora begins to dance for three days straight. Upon the completion of the third day, the creature dies from exhaustion. The warrior then crafts a mask from his armor.

Fierce Deity
Many fans believe that the Traveling Warrior is the personification of the Fierce Deity before being sealed in the Fierce Deity Mask. He must be the same person who Majora considers him as the true bad guy, probably for sealing his soul in a mask. This is supported by the fact that the warrior bears many similar features to the Fierce Deity and, consequently, Link.

Terminan Link
Some fans believe that the hero could be the Terminan equivalent of Link. Similarly to how the traveling hero resembles the Fierce Deity, he also greatly resembles the Hero of Time and Hylia's Chosen Hero. However, it is impossible for the hero to be a Terminan since he was from a different world which would probably be Hyrule.

Link's Ancestor
Another possible identity of the hero is that he may be one of Link's ancestors, like Lord Raven from the Oracle of Ages manga. He rather looks more like the Hero of Men.