King Dodongo, also known as the Infernal Dinosaur, is a boss that appears in The Legend of Zelda: Ocarina of Time. He is a giant Dodongo fought at the end of the game's second dungeon Dodongo's Cavern.
The Legend of Zelda series
King Dodongo is the source of the Dodongo infestation inside Dodongo's Cavern. While the rock-eating Gorons where mining for high quality rocks needed as food they unwittingly stumbled upon King Dodongo and his nest which spilled out into the rest of the mines. When the Gorons sent a message to the King of Hyrule asking for aid, the evil Gerudo tyrant Ganondorf arrived instead and blocked the entrance with a giant boulder, demanding that the Goron chieftain Darunia give him the Goron's Ruby before anything is done about the infestation.
King Dodongo is heavily armored and nearly impervious to all of Link's attack but can be defeated by tossing a bomb into his mouth while he's preparing to breathe fire. The bomb will explode inside of his stomach, stunning him and allowing Link a chance to run up and slash his head. Occasionally, King Dodongo will curl up into a ball and roll around the arena attempting to crush Link. After receiving enough damage, King Dodongo will become disoriented and roll into the lava in the center of the room which cooks him alive.
Hyrule Warriors series
King Dodongo appears as a Boss in Hyrule Warriors, Hyrule Warriors Legends and Hyrule Warriors: Definitive Edition. Like in the regular Zelda games, King Dodongo must be beaten by tossing bombs inside of its mouth and attacking it while it is laying on the ground. He appears in Story Mode but also on the various missions of Adventure Mode.
Super Smash Bros. series
Super Smash Bros. Brawl
In Super Smash Bros. Brawl, King Dodongo makes an appearance as a sticker.