Even though your main battle involves your hero fighting your villain, neither one are battling alone. The hero has allies and your villain has his own henchmen. No matter how powerful your villain might be, he can’t do everything or be everywhere. That’s why your villain needs allies of his own, otherwise known as henchmen.
A villain’s henchmen serve three basic purposes. First, the henchman can challenge and fight the hero early in the movie. Your hero’s battle with the villain should be saved for the end. For example, suppose Darth Vader personally came to Luke’s planet, looking for R2D2 and ran into Luke. Then Luke and Darth Vader battled until Luke won. That would be the end of the movie after about 30 minutes.
Since your villain can’t fight your hero face-to-face too soon, your villain needs henchmen who can afford to lose a battle with the hero early in your story. In “Die Hard,” all of those other nameless terrorists battle Bruce Willis as he picks them off, one by one. Bruce Willis can’t kill Hans, the head terrorist until the very end or else that would be the end of the story.
Second, your villain’s henchmen can advance the plot by being someplace that the villain can’t be. In “WALL-E,” Auto, the evil auto-pilot computer, is physically restricted to the captain’s cabin. To try and get rid of the plant, Auto has to give the plant to his henchman, the little Gopher robot that tries to destroy the plant by placing it in an escape capsule and blowing it up in space.
In “Die Hard,” the terrorists actually have two unintentional henchmen. The first are the incompetent FBI and police who are making Bruce Willis’s life miserable. The second are the TV news crew that learns of Bruce Willis’s identity and reveals who his wife is. Although neither the news crew or FBI are working for Hans the terrorist, they’re aiding the villain and thus working as the villain’s henchmen.
Third, your villain’s henchmen forms a subplot that can reveal details about your story that we might not learn otherwise. For example, Hans the terrorist would never have been able to figure out Bruce Willis’s link to his wife if it wasn’t for the blundering of the TV news crew.
Despite aiding the villain, the villain’s henchmen often butt heads with the villain, forming a minor subplot. In “Die Hard,” Hans the head terrorist struggles to control one of his terrorists who seeks revenge against Bruce Willis. While Bruce Willis has to fight against Hans and his army of terrorists, we now have the subplot between the vengeful terrorist seeking to avenge his brother’s death vs. Bruce Willis. By giving one of the villain’s henchmen a goal of his own, this subplot helps grab our attention and maintain suspense while we also wonder what’s going to happen with Bruce Willis in his fight against Hans.
The villain’s henchmen provide additional threats against the hero. Instead of Bruce Willis fighting against Hans and his army of terrorists, we now have Bruce Willis fighting Hans and his army of terrorists along with Bruce Willis fighting against the vengeful terrorist who wants to avenge his brother’s death. Same threat, but making this other villain’s henchman so vengeful makes him a secondary threat than just another faceless terrorist trying to kill Bruce Willis.
To make sure your villain has henchmen helping him battle against the hero. Think of two different henchmen who can aid your villain.
In “Die Hard,” the three main categories of henchmen are the other terrorists, the FBI, and the news crew. In “Star Wars,” the other henchmen are the Death Star generals, the stormtroopers, and the San People. The villain’s henchmen don’t always work directly for the villain, but they can still serve the villain’s purpose anyway.
The more you can define your story with both your villain and his henchmen, the more likely your story will feel real, multi-dimensional, and compelling. Fail to create any henchmen to help your villain and your whole story risks dragging until the final conflict between your hero and the villain.