Medigoron

Medigoron is Biggoron's younger brother. He's a size smaller than Biggoron, but 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 claims to be as good as his brother as smithing, and asks Link to pay 200 Rupees in exchange for the Giant's Knife, a blade which turns out to be essentially useless as it breaks after using it 100 times.

Majora's Mask
He also appears in Majora's Mask, this time making the devastating Powder Keg. He is also the Goron that gives Link his Powder Keg Certification, a certificate proving he knows how to use the Powder Kegs.

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).