Canadian Jon Klassen is an author and illustrator of children's books, and also works in animation film. He became world-renowned with the hat trilogy, a visual comedy in three acts: I Want My Hat, This Hat's Not Mine, and We Found a Hat. For the second title in the series, he received the Caldecott and Kate Greenaway Medals. With a very particular illustration stroke, he also signs, with Mac Barnett, the famous trilogy of shapes: Triangle, Square and Circle.