A memorable roleplaying villain is much more than a stat block or a bunch of numbers. It's one that strikes a psychological connection with the players. It's one that is talked about fondly long after the last fight or campaign is over. A memorable rpg villain is the culmination of all the player and character efforts and the last fight of the campaign. Here I will discuss the different aspects of what makes a great villain and one which your players will enjoy.

The villain must have a connection to the PLAYERS
You have your hit points and powers and stats all ready to go for your villain. The villain has been terrorizing the characters and the countryside. But do the players themselves really care? As a game master it is often easy to forget that there are two personalities that the villain is fighting; the character and the player are separate. To be a memorable villain there must be an emotional and psychological connection with the players. When the players are more involved and have an interest in the villain they'll have more fun and have a personal stake at defeating the villain. They will be almost driven beyond their control to defeat the villain because they now have a personal stake at the villain's defeat.

A memorable RPG villain looks evil
The description of the villain is one of the first things the game master presents to the players about the villain. It's important to set a strong and immediate sense of evil and wickedness with your villain. Colors are important symbols and should not be overlooked. Black symbolizes darkness and night time in which people have a hard time seeing what is beyond their reach. There is so much real life association with the color black and evilness that it's an easy option for the game master. It is the opposite of white which symbolizes light and goodness. While not as powerful an association, red is also a strong evil color. It's the color of blood which more often than not is a bad thing. When was a lot of blood thrown around in a setting been a good thing? The game master can take these colors and add them to several parts of a villain's appearance. Hair color is an obvious one where movies have conditioned us that the black haired person is the villain while the blonde or light brown is usually the innocent. Symbols and clothes can also carry color meaning.

A memorable RPG villain has an evil name
Think about the infamous villains from movies and literature. Darth Vader is a prime example. Darth is similar to dark and Vader is similar to invader. Word variations are common elsewhere with Draco (dragon) and Snape (snake) from Harry Potter also give a sense of villainy. Just like with physical appearance, imagery can be taken from the color black or things that are black. People with the name of Onyxvein or Nightraven aren't going to bring up images of cheerful innocents.

A memorable RPG villain has foiled the players in previous battles
There are few things more irksome to players then a villain getting away. Not only have they missed out on potential experience points or improved equipment but they were bested and defeated. With every fight afterwards, there is a little bit more urge to finally succeed where they failed before. Some care is needed by the game master in this. The villain must be able to flee in a realistic way or there could be a feeling from the players that they were purposefully cheated and never had a chance in the first place. Additionally the villain cannot keep fighting and fleeing too many times or the players will become more annoyed then interested in fighting and you will have the opposite psychological effect that you want.

A memorable RPG villain has unique and interesting surprises for the players
The players have waded through the minions of our villain and are ready for the big fight. The villain steps forward and draws their sword and attacks until defeated. This scenario turns into just another fight and one the players have already done many times in getting to the villain. Going back to our Darth Vader example it at first seems odd that in a world of laser guns and spaceships someone would use what is basically a sword. Not until we are surprised when it deflects laser blasts and cuts through walls do we see why someone would use a lightsabre. Anything new and unexpected will throw a wrench into the player's plans that they have made for the villain. If the villain has fought them in the past then they will know the strengths and weaknesses of the characters and can use that in the climactic fight.

A memorable RPG villain challenges the players as much as the characters they control
A villain's stats and numbers challenge the characters but as we talked about before there are two people behind a character. If the villain can engage and challenge the characters they will be more inclined to find the villain memorable. Ways to engage the players can be done by the use of riddles that need to be solved. Adding in hints in the campaign weeks or months before about how to defeat the villain challenges the player's memory. Unique and new battlefield terrain and situations will give the player's pause as they try to figure out what is about to and what is happening in combat. Basically what we want here is to make the players do more than just roll dice and repeat the same maneuvers they have done in every past game session.

A memorable RPG villain challenges the player's morals
Challenging a player's morals is one of the strongest psychological tools that a game master has. A character will be outraged at a villain desecrating their religion or wiping out their home town but does the player care? A villain could wipe out a merchant's trading caravan but will the players really have a connection to what that means on an emotional level? By bringing in real life connections that a player, and not the character, can associate with you will gain a huge psychological connection that will all but force the player to hate the villain. For example if any of your players are school teachers have the villain kidnap, threaten, or hurt children. Additionally if any of them are parents then have the captured children be the same age and gender as the player's children. Any player that is a pet lover will be angered by a villain killing innocent animals needlessly. The key is to find out what pulls the heartstrings of the players as people in their day to day lives and then gently pull them. Gently being the keyword and a game master should be cautious about overdoing it and not pushing the players psychologically too far. Keep in mind that many of the above responses could be automatic and quite strong.

A defeated memorable RPG villain is talked about long after the campaign is over
I've covered several different aspects of what makes a villain memorable. Their physical characteristics draw up mental images for the players. The players speak the villain's name further drawing up a psychological image of villainy. The villain keeps escaping and denying the players satisfaction. Lastly the villain targeted the player's morals as much as their characters. In the end the campaign is a success for the game master in the sense that the players had a great enjoyable time overcoming their foe with all of the buildup given to them from the game master.