Can you think of a great hero who is made greater because of a villain who counters them perfectly?
Batman is at his most iconic when he’s facing the Joker. When Loki gets out of line, it’s Thor who has to be at the top of his game. And Harry Potter might have lived a relatively normal life without Voldemort causing trouble.
Sherlock Holmes has Moriarty. Ripley has an infestation of aliens. Luke Skywalker versus Darth Vader. Ariel versus Ursula.
However you choose to define a hero, you can often find an antagonist who has the exact set of qualities needed to make the hero who they are.
So does every story need a villain?
Conflict creates interesting stories
The purpose of conflict is to provide tension, not just for your characters, but also for your reader. In stories where the hero has everything they need to succeed, obstacles turn into distractions at best, and at worst become a waste of time. A reader who knows that the hero can’t be stopped from achieving their goal will have little incentive to read until the end.
Conflict can come in many forms. When conflict is external, the hero often has an obvious antagonist. This may take the form of a villain, but can also include societal oppression or even forces of nature. Internal conflict can be less obvious, but can be visible in the form of deep character flaws, including personal or medical issues such as addiction, or self-doubt.
Whatever form the conflict may take, conflict leads to story arcs that compel your reader to stick around.
Villains create conflict
As mentioned earlier, villains are a visible form of external conflict. When a character in your story is positioned with an opposing set of goals to your protagonist, it’s immediately obvious to your reader what’s stopping the hero from succeeding. Will the hero get what they want? A well-structured villain can plant those seeds of doubt in your reader’s head. The only way to know for sure is to keep reading.
Let’s consider Sherlock Holmes. While it’s probably true that his world would always have troublesome crime, Sherlock shines when facing a villain who puts even his great mind to the test. A common thief would pose less conflict for Sherlock, and would therefore pose less interest for a reader.
Conflict doesn’t only come from villains
Remember when we brought up internal and external conflict? Villains are a single example of conflict, but they’re not the only source of trouble.
Villains cause conflict. So does the threat of Armageddon. Some societal rules can stop a hero dead in their tracks, at least until the hero figures out how to rise above them. There are lots of ways to produce conflict. As an author, you’re in the enviable position of getting to choose which one to throw against your poor hero. And you know what? They’ll come out of the conflict even stronger than before. They might even thank you for it.
If you’ve got a villain in your story who isn’t pulling their weight, why not consider replacing them with some other source of conflict? Give your character a flaw, and make it serious. Put them in the way of some real risk, and make their success ambiguous, at least as far as the reader knows.