Horrid Henry is a popular children's book series written by Francesca Simon. The stories follow a mischievous boy named Henry who often gets into trouble due to his naughty behavior. He has a younger brother named Perfect Peter, who is the opposite of Henry, always behaving well and pleasing their parents. The series features various adventures and antics, showcasing Henry's schemes to avoid chores, outsmart his friends, and deal with his rival, Rude Ralph. The humorous tales are illustrated by Tony Ross, making them engaging for young readers and helping to teach lessons about behavior and consequences.