Archetypes.

 It came to me as a surprise too, but this topic, Archetypes, was something that interested and entertained me a lot. Every story has roles for all the characters introduced in it, the most prominent of them being the protagonists and the antagonists. 

The protagonist, also the "hero" of the story.

The Mentor is the hero's guide on how to live or in some cases, how to "survive".

The Allies or the friends are those who help the hero. 

The Herald is an event or person that makes the call for adventure. It is the catalyst to the story.

The trickster is the clown or mischief-maker who brings comedy and humour. 

The shapeshifter, other than the literal shapeshifter such as a werewolf; is also someone who betrays the protagonist. The ally that is suddenly revealed to be the enemy. 

Threshold guardians are the forces that stand in the hero's way. 

The Antagonist is the "shadow" or the villain of the story.

Damsel in distress is the girl who needs a knight in the shining armour to save her. 

The lover is the irrational person who uses his heart as a guide rather than his head. 

The magician is quite self-explanatory, but he is the person who understands the way of the world to achieve key goals. 

The outlaw is the rebel who never abides by the rules. 

The innocent is the morally pure character. 

The creator is the "inventor" who creates things. 

I personally dislike the lover and the damsel in distress archetype, because, in my opinion, they are so overly used in the media society that it has grown annoying.