Bulls (known as Cattle) are one of the toughest and fastest beasts in the world of Narnia. Bulls can run very fast, and they can easily use their horns to bash their enemies. They are not to be confused with Human-Headed Bulls or a minotaurs. Female bulls are cows.
In The Magician's Nephew, a bull and a cow were risen out of the ground with beasts that heard Aslan's call, after the world of Narnia was created.
In The Lion, the Witch, and the Wardrobe, bulls were mentioned in the gathering in Aslan's camp, when the Pevensies and the Beavers arrived to meet Aslan. Lucy thought what she saw was an ordinary bull, but it was a human-headed bull. Bulls fought in Aslan's Army against the White Witch's Army during the First Battle of Beruna.