#23: Four Christmases
When it comes to specific film genres, there are likely people and characters that are relevant to that theme somehow, and often make cameo appearances for whatever reason. More often than not it seems like the director needs to fill a role and this is the perfect way to do it.

Take Peter Billingsley in Four Christmases for example. He is like THE guy to call when you need to fill a slot in a Christmas movie. Most recognized for his role in the 1983 film A Christmas Story, Billingsley also appeared in the Christmas comedy, Elf.