Mortimer is a fictional character created by the author Robert Munsch. He is known for his playful and mischievous personality, often getting into humorous situations. Mortimer's adventures typically revolve around his interactions with family and friends, showcasing themes of imagination and childhood. The most famous story featuring Mortimer is titled "Mortimer," where he refuses to go to bed and instead sings loudly. This story highlights the challenges parents face when trying to establish bedtime routines. Mortimer's character resonates with children, making him a beloved figure in children's literature.