Knuffle Bunny: A Cautionary Tale is a classic children's picture book written and illustrated by Mo Willems. Released by Hyperion Books in 2004, Knuffle Bunny received the 2005 Caldecott Honor. The story spawned an animated short film and a musical play, as well as two sequels. The Knuffle Bunny Series has sold more than 750,000 copies. The series' protagonist, Trixie, is named after Willems's real-life child.

Mo Willems is an American writer, animator, voice actor, and children's book author. His work includes creating the animated television series Sheep in the Big City for Cartoon Network, working on Sesame Street and The Off-Beats, and creating the popular children's book series Elephant and Piggie.