Jack Horner is a fictional character in the comic book series Fables by Bill Willingham. His first appearance was in issue #1 of Fables and continued as a regular character of the series until leaving the series for his own title, Jack of Fables. The character is based on various nursery rhymes and fables with characters named Jack including Little Jack Horner, Jack and the Beanstalk, Jack and Jill, Jack Be Nimble, Jack Frost, Jack O'Lantern, and Jack the Giant Killer and others.