Yerbal is a character from The Legend of Zelda: Skyward Sword. He is a Kikwi living in Faron Woods. Yerbal once climbed the Great Tree and has refused to come back down. Because of this, he is known as the Kikwi Hermit. He has a distinctive and loud snore.
When Link scales the Great Tree, Yerbal tells him about Farore's Flame, making Link promise not to tell anyone about the information (however if Link refuses he will tell him anyway). He references the Secret Moblin from The Legend of Zelda when he says, "All right, I'll tell you. But remember-- it's a secret to everybody." Despite this promise, Faron manages to deduce how Link learned where she was located, and implies that she will eat Yerbal the next time he arrives at Lake Floria as punishment. If Link talks to Yerbal after opening the door to Lake Floria, he will remind Link not to tell the Water Dragon that Yerbal told him how to find him.
If Link talks to him while searching for the Sacred Water for Faron, Yerbal will point out that Faron is fond of the water from a spring inside the Skyview Temple. If Link talks to him after obtaining some Sacred Water, but before Link gives it to Faron, Yerbal will confirm it is the Water Faron desires and states that if Link is embarrassed to give it to Faron, he can tell her it was a gift from Yerbal.
In Hero Mode, Yerbal's dialogue will change, and he will not tell Link the same information about Farore's Flame that he did in the first quest, telling him he should know where to go. Should Link tell him that he does not know where to go, he will tell him the same information from the first quest.
As many Kikwis seem to be named after varieties of tea, it is possible that Yerbal is named after yerba mate. Alternatively, his name may be derived from the word "herbal", as in herbal tea.