"This giant horse is the last of its kind. Its physical capabilities completely overshadow those of regular horses, but its temperament is extremely wild. Only a truly skilled rider can train, or even catch, this beast of a mount. This is a horse that chooses its rider."
The Giant Horse is a special type of Horse found in Breath of the Wild. There is only one to be found in Hyrule, and it rests in the Taobab Grasslands, in the Lake Region. It can be found in a clearing surrounded by other horses. It is easily distinguishable, since it is much larger than other horses. It's assumed to be related to Ganondorf's horse.
Once registered, this horse cannot be fitted with other saddle or bridle than the ones provided, and its mane cannot be changed.