The short was so popular that Walt Disney produced several sequels, which also featured the Wolf as the villain. The first of them was named after him: The Big Bad Wolf, also directed by Burt Gillett and first released on April 14, 1934. In the next of the sequels, Three Little Wolves (1936), he was accompanied by three just-as-carnivorous sons. (These three sons were later reduced to just one who, in contrast to his father, was full of goodness and charm and a friend of the Three Little Pigs. ) The fourth cartoon featuring the Three Little Pigs and the Wolf, The Practical Pig, was released in 1939. During World War II, a final, propaganda cartoon followed, produced by The National Film Board of Canada: The Thrifty Pig (1941).