The Mystery of the Third Planet, aka The Secret of the Third Planet is a 1981 Soviet traditionally animated feature film directed by Roman Kachanov and produced by the Soyuzmultfilm studio in Moscow. It is based on a children's science fiction novella "Alice's Travel" by Kir Bulychev, from Alisa Selezneva book series. The movie is considered a cult classic in Russia and was included in various lists of the best animated films and science fiction films.