"Horrid Henry" is a children's book series written by Francesca Simon. The series follows the misadventures of a young boy named Henry who is known for his mischievous behavior and love of pranks. In the "Horrid Henry" books, readers follow Henry as he navigates various challenges and obstacles, including school, family life, and his relationships with friends and enemies. The books emphasize themes of humor, creativity, and the importance of learning from one's mistakes.