source: springhole

• any motivation can be a villainous one. what makes a motivation villainous is that someone is willing to unjustly or excessively hurt someone else to see it through.
• all kinds of people from all walks of life can be villains. think about people you've met or known about over the years. and ask yourself: what might someone living their lives be doing to hurt someone?
• villains do not have to all be good, rational or sympathetic, just because they need motivations for what they do.
• villains who are all talk and no actions are not scary. show your villains doing bad things to other characters, especially ones we love or want to be safe.
• there are a number of ways villains can hurt people: physically, materially/financially, psychologically, socially, academically, professionally, etc. keep things fresh by having your villains use an assortment of ways to make the heroes miserable.
• always be able to provide plausible answers for both: what does my villain stand to gain or think there is to gain from this? and why does my villain think this is the best way to get it?