Doc Bandam

In The Wind Waker, Doc Bandam is the eccentric man who owns the Chu Jelly Juice Shop on Windfall Island. He supplies the Great Sea with medicine straight from Chu Jelly. He loves his work and wants people to donate Chu Jelly to him in order to research new potions. Every time Link gives him more Chu Jelly, he will give him a free sample of the new potion, either a red, green, or blue potion, depending on what type of jelly Link gives him. Even if he has already made that type of potion, he will still give Link a free sample. Doc was born on Windfall and frequently takes trips to Pawprint Isle to collect samples of Chu Jelly from the many ChuChus that live there. Link has to bring him five Chu Jellies in order for Doc to construct a Red or Green potion, but fifteen are needed to make a Blue potion. The type of potion Doc makes depends on the color of the Chu Jelly that Link brings him.

Besides being a talented potion maker, he's also fluent on physics, as seen when Link tries to buy a potion without carrying an empty bottle.

Trivia
Rabbitland Rescue Man from Spirit Tracks bears some physical resemblance to Doc Bandam.