Bullbo

Bullbos are giant boar creatures that are used as mounts by Bulblins. Their charging is immensely powerful, though they tend to lose control of their direction at high speeds.

The Legend of Zelda: Twilight Princess
In The Legend of Zelda: Twilight Princess, Bullbos primarily appear in scenes where Bulblins are shown pillaging, with the Bullbos' speed allowing for abrupt attacks and retreats. The player first faces them in a horseback battle in Hyrule Field outside of Kakariko Village, where each Bullbo is ridden by two Bulbins. One acts as a handler, and the other is an archer shooting at Link. If Link knocks the handler off, the Bullbo with go berserk and throw the archer off if it is not already. Attacking Bullbos themselves causes them to charge a bit before falling onto their sides, eventually getting back up. Unridden Bullbos tend to be nonaggressive, usually just standing in place.

Unridden Bullbos can be found most prominently around Gerudo Desert, particularly around the Bulblin camp. A few remain even after it is destroyed, and can be ridden. If Link spurs one while riding it, it snorts, rears up, and barrels forward for a short period. They can break wooden structures like walls and watchtowers while charging, but also do not stop for rock walls or cliffs, causing them to crash (throwing Link off) or fall. They are among the only animals that Wolf Link cannot talk to. The Bulblin camp also has a roasted Bullbo carcass on a spit over a fire; attacking it repeatedly reveals a Piece of Heart.

The Legend of Zelda: Spirit Tracks
In The Legend of Zelda: Spirit Tracks, Bullbos start appearing in pairs on the overworld once the Snow Realm is opened. Unlike most previous enemies found on the rails, they are not easily scared off by the whistle. They are more aggressive in this game, attempting to ram the player. The initial encounter with them causes Zelda to realize they need better offensive capabilities aboard the Spirit Train, and suggests asking Alfonzo, who makes them a cannon. Once the Snow Temple is cleared, they sometimes appear ridden by Bulblins. They appear in the Forest Realm, the tundra portion of the Snow Realm, and in the Fire Realm. In this area, they can be instantly defeated by getting hit by a falling rock or Dark Train.

Trivia

 * During the design phase of The Legend of Zelda: Breath of the Wild, the generic boars that appear in the final game were intended to be Bullbos, though their conceptual variants were simply referred to as "Snow Boar," "Black Boar," and "Master Boar." This may have been changed to better distinguish between "normal" and "monster" species.