(a ton more useful information about screenwriting)
antagonist
A major character whose values or behavior conflict with those of the protagonist, leading to a change in the protagonist. In certain stories, the antagonist is not a character per se, but is rather a force: the elements, society, etc.
Origin
The word “antagonist” is derived from the Greek word antagnistes, which means rival or opponent.
Antagonist vs. Villain
Some writers use “antagonist”, “opponent” and “villain” as interchangeable. This is only useful when the protagonist and hero are the same character.
It’s also important to realize that the antagonist is not necessarily a bad guy. In many stories, the antagonist is ultimately working in the protagonist’s best interest: the coach who won’t let the athlete give up on himself, the quirky girl who the hero falls in love with despite his rules, or the messy dog which gets the fastidious shopkeeper to loosen up.
Examples
In the 2005 movie version of Charlie and the Chocolate Factory, Willy Wonka is the protagonist, while Charlie is the antagonist. Charlie causes Willy to change; that’s the nature of a protagonist-antagonist relationship.
