Gamahiro is a giant toad from Mount Myoboku, sometimes just called "Hiro" for short.
He first got summoned way back in Part I, but didn't actually get named until Part II when he showed up again. In the anime, his design shifted noticeably—he started out green and brown, then got recolored to a light-blue-greenish shade during the Pain arc to match what was going on in the manga.
One odd thing about Gamahiro: he's actually talked in the anime, but in the manga itself, he's stayed silent the whole time. Fans have noted this inconsistency between the two versions.
Content compiled by AnimeList.moe from publicly available sources.
