I was just having an online chat with a friend about a story he’s writing, and when I asked about why the villain in the story did what he did the answer was what I characterized as “hating cats because they’re not dogs”. It was a motivation, but it wasn’t one that the audience was likely to be able to identify with.
Someone once wrote that a good villain should be one the audience understands, and I agree. I think that in order to make villain anything more than “I’m evil!” you need to make them come alive in some way, and make the audience understand them. The audience shouldn’t (generally) like them, mind you, but they should understand clearly where this character is coming from. It makes them solid in the audience’s head, and gives the audience something more to work with in terms of making the character come alive.
One of the simplest ways to do this is to make the villain’s motivations based on good old-fashioned human needs. They’re things that everyone has, so they’re things that everyone can relate to on some level. If you want a quick list of them, the best place to look is Maslow’s Hierarchy of Human Needs, a chart which shows the basic requirements that Maslow believed all humans need to feel safe and secure in their lives. Maslow believed when one of these needs it out of sync or not being fulfilled it caused mental illness or other issued in the person. I think to take it another way- the desire to fulfill these needs can be seen as a motivation for a great many of the things that humans do, and it’s these unfulfilled desires that drive us.
Many villains are actually following twisted or extreme examples of the desire to fulfill these needs. Let’s take a look at a few…
DarthVader- Safety/Security, he was trying to preserve the security and peace of the people in his own twisted way.
Sauron- Power, but power as a means to Safety/Security.
Lex Luthor- Power, but again Power to Luthor seems to be about Esteem, he doesn’t just want to beat Superman, he wants the world to respect him.
Orochimaru- Safety, he’s afraid of death and is desperately looking for a way to avoid it. He’s also trying to become more powerful to overcome his enemies who threaten his Safety.
Now, this doesn’t mean the villans can or should have only one motivation, but there is usually a core motivation which drives them in what they do. Once you as the writer know what that motivation is, the villains should generally write themselves. This is important because a hero is often judged by their villains as much as they are by what they do.