The hero must battle a villain. Sometimes that villain can be a force of nature but in most cases, it’s best to have a human hero battling a human villain (or in the case of movies like “Thor,” a god fighting another god). Basically, the human and villain must be nearly the same type of people so the hero essentially battles an evil version of him or herself.
To make a worthwhile villain for your hero to fight against, your villain needs a What and a How. The What defines what the villain wants. Bad movies create villains who exist for no other reason than to fight the hero, but with no purpose or goal. Watch “The Dark Tower”m to see a villain who seems to have no goal or purpose beyond trying to stop the hero.
Ideally, your villain must want to achieve a horrible goal. The villain in “Die Hard” wants to rob a corporate vault and hold an entire Christmas party hostage. That may seem bad enough but what really makes a villain despicable is the How. For example, how does the villain want to achieve his or her What?
In “Star Wars,” Darth Vader’s What goal is to destroy the rebels before they get too strong. That’s bad enough, but the How defines how he goes about it, which is to blow up entire planets with the Death Star.
The What is bad enough, but the How really shows how evil the villain might be.
In “Avatar,” the What goal for the villain is to get at the minerals underneath the aliens’ sacred Hometree. How the villain plans to do this is by slaughtering all the aliens.
In “Kingsman: The Golden Circle,” the villain’s What goal is to legalize drugs and avoid criminal prosecution for the past. How she plans to do this is by holding drug users around the world hostage by threatening to kill them until the President agrees to give her amnesty.
Think of a horrible goal for your villain to achieve and then make it worse by defining How the villain hopes to achieve his or her goal, usually through by massive suffering to innocent people. Even if your villain won’t hurt others, you need to make him or her less than likable. In “Rocky,” Apollo Creed is the villain but what makes him worse is how boisterous he is. In “The Karate Kid,” the villain is the bully. What makes this villain worse isn’t just that he’s a skilled martial artist, but that he’s taunted and beaten up the hero in the past.
Make the villain’s path to a goal involve hurting innocent people. If that’s not possible, then make the villain despicable. That will go a long way towards making your villain a feared foe for your hero to defeat.