Sheik
A mysterious warrior with a great wisdom and strength. He is one of the last remainders of the legendary Sheikah tribe who protect the royal family of Hyrule. Sheik helps Link along his quest while he never reveals who he is and why he is aiding Link. His speed and focus make him a very powerful ally in stopping evil's wishes.
It is later revealed in the game, that Sheik is actually someone you've been looking for the entire game.