A villain is an example of an archetype. The Incredibles, the character in question Syndrome. He's there to create the major conflict with the protagonist's the Incredible's family.
Allusion is a figure of speech, which someone refers directly or indirectly to an object or instance from a different story or such. For example, someone could say to another well known person,"Don't be a Hitler." They would be referencing a historical figure that had a bad influence.
