In The Legend of Zelda: Twilight Princess, the Goron leader who becomes a boss is Darbus.
Darbus is the patriarch of the Goron tribe on Death Mountain. While investigating strange volcanic activity in the Goron Mines, he is corrupted by the power of the Fused Shadow. The Goron elders imprison him inside the mines after he transforms into the lava-like monster Fyrus.
Link eventually confronts Fyrus as the boss of the Goron Mines, the game's second major dungeon. After Link defeats the monster and removes the Fused Shadow's influence, Darbus returns to his normal form. His transformation is central to the Goron portion of Twilight Princess's story.
Gor Coron is a common source of confusion because he is one of the Goron elders and temporarily leads the tribe while Darbus is imprisoned. Darunia is also a famous Goron leader, but he belongs to Ocarina of Time. Darbus, meanwhile, serves as Twilight Princess's patriarch rather than one of its four village elders.