Don Gero is a character from The Legend of Zelda: Majora's Mask. Although never seen in person, he is the conductor of the Frog Choir. His mask can be obtained after Link brings Rock Sirloin to the Hungry Goron in the Mountain Village. The description of Don Gero's Mask states that it looks just like Don Gero himself. If Link wears Don Gero's Mask, the frogs from the choir will believe him to be Don Gero. They will comment that he has lost weight, indicating that the real Don Gero may actually be larger than the mask indicates.
"Don" is an Italian, Spanish and Portuguese honorific given to a male individual of great importance, such as noblemen. "Gero" is the Japanese onomatopoeia for a frog's croak.