Villains are a dime a dozen, but good villains—the ones that stick in your mind—are just as hard to write as good heroes, no matter your genre. The best villains are never purely evil, or evil just because. That complexity is the key to creating a bad guy who stands out.
Two Types of Villains
When you boil the bad guys down to their utmost basics, you end up with two generic types: the ALIEN and the HUMAN. I’m not necessarily talking about science fiction. The Alien type can be found in mysteries, thrillers, occult, and so on. Let’s have a closer look.
The Alien type. Don’t try to understand it—it is foreign to your human thinking, and no amount of human psychology or logic can unravel its motives and methods. Using the Alien type relies on the idea that we fear what we do not know. The problem with this type is that it’s commonly written by humans, and so it often falls flat or comes off as one-dimensional.
The Human type. This is a form of evil which we can understand to some extent. It’s based on human emotion or logic, however skewed or taken to extremes, and has a base we can identify with. This type of villain relies on the idea that we fear the darkness inside us. It often has more impact because it resonates with us.
Let’s focus on the Human type of bad guy.
A Well-Rounded Character
Your Human villain is often as important as your protagonist, and as such, should be a well-rounded character in itself. Ask questions about his childhood, his beliefs, his desires and dreams. Get to know it as well as you know your heroes.
The main difference between your villain and your hero is that your villain (often) will not have character development, and being stuck in his evilness, will be vanquished.
(So many interesting stories are waiting for you if you dare to break that rule!)
The key point to remember is that a villain rarely thinks of himself as evil. He’s the hero of his own story, and often perceives himself as justified in his actions. (That’s another rule that’s fun to break.)
Ten Motivations for Villains
(Click to expand)
Greed. I want more money, no matter the cost.
Played moderately: I will dab in shady deals to win more money.
Played full out: I will backstab for the better deal.
Played to the extreme: I will sell out humanity for the right price.
A straight cause: I grew up rich. I’m conditioned for more of it.
A reversed cause: I grew up poor. I will change my fortune.
Played moderately: I will lord it over every one I outrank.
Played full out: I will work to extend my reach over mankind.
Played to the extreme: I will rule the universe.
A straight cause: I’ve always lived among powerful people. It’s a way of life.
A reversed cause: I fear my own weakness and I will cover it.
Played moderately: I will court you ruthlessly.
Played full out: I will play dirty to get your love.
Played to the extreme: I will annihilate any competitors and take you by force.
A straight cause: I love you.
A reversed cause: I will compensate for you not loving me.
Played moderately: I will see you fail or fall.
Played full out: I will end you.
Played to the extreme: I will take away everything you hold dear and torment you forever.
A straight cause: You’re everything I hate.
A reversed cause: You’re everything I want to be.
Honor. I’m honor-bound to follow this path.
Played moderately: My position (work, army, family, etc.) requires me to be nasty.
Played full out: I dislike what I have to do.
Played to the extreme: I will sacrifice my soul to evil on the shrine of honor.
A straight cause: I value honor more than right or wrong.
A reversed cause: I value honor and I can’t tell right from wrong.
Played moderately: I will go to lengths to command respect.
Played full out: Respect me or die.
Played to the extreme: I will subjugate the galaxy.
A straight cause: I’m a proud man.
A reversed cause: Deep inside, I’m insecure about myself.
Justice. You will pay for your crimes.
Played moderately: I will get you arrested for what you’ve done.
Played full out: I will take the law into my own hands for what you’ve done.
Played to the extreme: I will destroy you and the system that has let you go free.
A straight cause: You have wronged me or mine.
A reversed cause: If I’m to be held up for my actions, so will you.
Revenge. You will pay for what you’ve done to me or mine.
Played moderately: I will pay you back in turn for what you’ve done to me or mine.
Played full out: I will visit our suffering tenfold upon you.
Played to the extreme: I will eradicate you and yours.
A straight cause: You have wronged me or mine.
A reversed cause: You think you’ve hurt us. I will not let you live with that smugness.
Ideology. I believe it’s for the best.
Played moderately: I will obey my creed despite some ethical issues.
Played full out: I will kill for my creed.
Played to the extreme: My creed demands the death of all. So be it.
A straight cause: I believe in my creed wholeheartedly.
A reversed cause: I must believe in my creed, because I’ve gone too far to turn back now.
Superiority. I’m better than you.
Played moderately: I deserve more resources than you.
Played full out: I deserve more rights than you.
Played to the extreme: You do not qualify as a human being.
A straight cause: I was brought up that way.
A reversed cause: I’m secretly afraid of your powers.

There are many more reasons to be evil out there. How many others can you find?