Wilbur Monroe Leaf was an American writer of children's literature who wrote and illustrated nearly 40 books during his 40-year career. He is best known for The Story of Ferdinand (1936), a children's classic which he wrote on a yellow legal-length pad in less than an hour. Labeled as subversive, it stirred an international controversy.

The Story of Ferdinand (1936) is the best-known work by the American author Munro Leaf. Illustrated by Robert Lawson, the children's book tells the story of a bull who would rather smell flowers than fight in bullfights. He sits in the middle of the bull ring failing to take heed of any of the provocations of the matador and others to fight. The Story of Ferdinand was published in 1936 by Viking Books. Later, after the Spanish Civil War, it was viewed as having a political agenda. During World War II, the British Air Transport Auxiliary started flying into Europe after D-Day and their pilots, who were non-combatants, used Ferdinand the Bull as their call sign. The book has been adapted into two films, the 1938 animated short Ferdinand the Bull and the 2017 animated feature film Ferdinand.