Harry Horner is a fictional character from the nursery rhyme "Hickory Dickory Dock." He is often depicted as a clever and mischievous figure who engages in various antics. The rhyme itself features a mouse that runs up and down a clock, with Harry sometimes portrayed as the mouse's companion or a character involved in the story. In some adaptations, Harry Horner is also associated with the phrase "Horner's method," which refers to a mathematical technique. This connection highlights the character's versatility, as he can be seen in both playful and educational contexts, appealing to children and adults alike.