Vladimir Propp analyzed folk tales and identified common character types and narrative functions. According to Propp's theory, characters fulfill specific roles that move the story's plot forward. These roles include the hero, who embarks on a quest to rescue the oppressed; the villain, who opposes the hero; and the donor, who provides assistance to help the hero succeed. Propp also identified roles like the dispatcher, who sends the hero on their mission, and the princess and her father, who need help from the hero.