Good vs. Great Villains
The internet is full of advice on how to make good villains and how to make great villains, but a lot of it boils down to a few key points. The ones I see the most are:
- A great villain is the hero in their own story
- A great villain defines the hero's strengths and weaknesses, or emphasizes them
- A great villain is just as capable as the hero, but less restricted in some way
These three rules aren't necessary in every great villain, but every great villain has at least one.
Darth Vader, for example, is the hero in his own story in the Original Trilogy. He has his Empire he wishes to protect but suffers a great defeat when the Death Star is blown up sending him off on an adventure to personally eradicate the rebellion. Through this he discovers his son is still alive, and attempts to recruit his son only to be rebuffed. Finally, his son - acting as an antagonist as far as Vader is concerned - confronts him and forces him to change as Vader opts to side with his son and the rebels and cast down the Empire. Vader is a tragic hero in his story - the man who gave up so much for his Empire then dies to help tear it down over the love of his son.
Lex Luthor, for another example, is a great villain for Superman. Where Superman is strong, Lex Luthor is brilliantly smart. Where Superman represents the "every man" (or is supposed to from his rural Kansas upbringing), Lex Luthor represents the wealthy elite. Where Superman is from the rural country, Lex Luthor is a product of the urban city. They are diametrically opposed, each defining the other by being weak where the other is strong, and strong where the other is weak, and os when they clash you can be in for a real treat...at least until the writer gets bored and Luthor gets into a metal suit to go one on one with superman.
For the final example we have Moriarty. What makes Moriarty such a great villain is not that he is smarter than Sherlock Holmes, but that he is just as smart as Sherlock Holmes, but has his mind turned to more devious purposes. Moriarty works because he shows us what Holmes is capable of if he turns his faculties to more nefarious endeavors. He works because he is Holmes's match, a true equal, just as strong and limited in almost every way, and so when they meet it is always special if for no other reason because each can see themselves in the other. In a sense, Joker also works in this way (barring the hand to hand acumen of Batman, at least.)
Introducing The Villain
You have your villain, but how do you introduce them? For this you want to take a cue from saturday morning cartoons, comics, and other movies: introduce the villain on their own terms.
This doesn't have to be a fair encounter for the PCs, but it does have to be survivable. A good villain, a capable villain especially, isn't likely to show up weak and ready for defeat. They're going to be strong. They may, however, also be arrogant which is something that can let the PCs get away without breaking character for the villain.
Consider the number of villains we meet as they're in the middle of a caper of some sort, only for them to bounce away scot free as the hero is forced to handle some other issue. What that issue is depends on your group and the GM, but it should be memorable. If you can introduce your villain with them getting a win that doesn't feel forced, your players will likely begin to hate them for that alone.
Have An Escape Plan
You know what many players like to do to potential villains? Kill them. You know why? Because games condition them to do that. Killing the guy is where you get the XP from after all in many systems - especially those that introduced most of us to the hobby. Also, PCs tend to not like losing, and a bad guy getting away - no matter the situation - often comes across feeling like a loss even if it is at best a draw for the villain. Because of this, I've had players chase villains to rather extreme lengths, sometimes even not noticing that they were actually causing more harm and furthering the villain's goals all the while.
You want a way for the villain to escape this introduction encounter in mind. One that is actually prepared in game, and not a cheat for forcing the PCs to not kill the villain. If you force the villain to live it is a scripted story moment and loses impact. If the villain escapes because they had things in mind already? That makes them more memorable.
A Guy In The Wings
Don't be afraid to toss your villainous plans onto someone in the wings. If the PCs insta-meep your villain on first meeting, maybe someone else in the organization takes over and does it. This may feel like a cop out, but it is a way to salvage prepwork you've done. You just need to modify the motivations behind things. On the plus side with this, it can often mean the PCs have created their own villain and that is a wonderful thing all on it's own. Consider the ace fighter pilot, leader of Death Squad, and then Death Squad gets meeped by the PCs except for one guy who escapes...barely. Now all the Death Squad stuff can be pushed off, and come back as that one guy trains and prepares for revenge against the PCs that ruined his chance at fame and fortune. It's not just an encounter/challenge anymore, it is personal for that NPC and soon it will be personal for the PCs as well.