Bumper is the horse used by Madelyn when she became a Ranger in The Royal Ranger. He is a black and white piebald, a type of horse Maddie loved at Castle Araluen. He is known to be able to easily carry three young teenagers. Madelyn receives Bumper from Bob Saddler II and Will allows her to get on, but since she has not told Bumper the password, she gets bucked off and angrily accuses Will of knowing that would happen. (This is, of course, being very similar to the first time Will tried to ride Tug.) Bumper's password is 'Don't break me.'
Soon after, Madelyn sees that she can talk with Bumper and when she tells Will her idea, he jokes about it, but knows that all Rangers talk with their horses, like when Tug "talks" to him.
His name is 'Bumper' because he used to bump into objects when he was young and falls over. He still has a tendency to do it, but does not fall over anymore.