Medigoron

Medigoron is Biggoron's younger brother. He's a not as large as Biggoron, but is still larger than the average Goron. He opened a shop in Goron City where he forges blades, but he's not as skilled as his older brother.

Ocarina of Time
In Ocarina of Time, he owns a store in Goron City, and sells Link the Giant's Knife for 200 Rupees. The blade, despite having taken Medigoron some five or six years to make, has durability issues and turns out to be essentially useless as it breaks after using it 100 times or after striking a hard object. Though Link must use two hands to wield the Giant's Knife, Medigoron considers it to be a small weapon.

Medigoron's Blade Store is a tight fit for his enormous size, an unfortunate side effect of his lack of foresight.

Majora's Mask
He also appears in Majora's Mask, this time as the shopkeeper for the Goron Powder Keg Shop in the Goron Village Cave where he makes the devastating Powder Keg. After Link completes his test on proper usage of Powder Kegs, Medigoron gives him a Powder Keg Certification that proves his capability and allows him to purchase Powder Kegs anywhere they are sold. Medigoron admits, after Link gets his certification, that the test was really quite dangerous, and gives him a free Powder Keg in apology.

Medigoron is also the instructor of the traveling Goron who sells Powder Kegs at the Bomb Shop in Clock Town.

Trivia

 * Medigoron's name seems to be a portmanteau of medi- (from the latin medius, meaning middle), and -goron (believed to originate from the phrase "goron, goron", a Japanese onomatopoeia for the sound of a rolling rock).