His name is Yerbal. He is a hermit of the herbivorous Kikwi race.
Yerbal is Kikwi who sleeps atop the Great Tree. Link meets him while he is searching for a Farore's Flame. To wake Yerbal from his sleep, hit him with any projectile weapon. Then, Yerbal will direct Link towards Faron.
Humorously, when Link meets Faron, she announces that she will eat Yerbal for divulging her location. However, Yerbal remains very much alive for the rest of the game.