Propp

Propp is a russian theorist who studied russian folk tales.

His theory was to do with character types.
He identified 8 types of characters, which where:

- the villain (antagonist) 

- the princess or love interest

- the father or person with knowledge 

- the dispatcher who sends the hero off on his quest.

- the donor, who offers help 

- the sidekick, or helper, who is not as handsome as the hero.
- the hero (protagonist)

- the false hero: a villain who pretends to be good in order to trick the hero.

An example of a film with all these characters in would be Avatar.

In addition to the characters, Propp also has a list of 31 narrative functions, which are called narratemes.