Post reading..

I think that Great Gatsby has antagonists but not villains as we would find in the context of escape fiction. Generally Tom Buchanan is a very unsympathetic character. If you really want a villain, he might qualify. He is entitled, racist, self absorbed and vindictive.

Sort of. There are indeed antagonists, like Tom Buchanan, and protagonists, like Nick Carraway, our narrator for this story. But villians and heroes? Probably not. Certainly no heroes! Not one person steps up and "saves the damsel in distress", so to speak. Everyone is so melodramatic, and if they aren't melodramatic, they meet an end that is such (Gatsby, for example.). Hope this helps!