"Billionaire Boy" is a children's book written by David Walliams. It tells the story of a young boy named Joe who is the son of a billionaire. Despite his wealth, Joe struggles with loneliness and the challenges of fitting in at school, where his classmates often treat him differently because of his family's riches. The book explores themes of friendship, acceptance, and the importance of being true to oneself. Through humorous and heartwarming moments, Joe learns valuable lessons about life beyond money and the significance of genuine relationships.