In most of the games I have ever played, the endgame is typically to beat the final boss or the main villain and then you're done. You've saved the (insert whatever world/person/etc. you saved for the 1,000th time here) again and it is all done. The hero has won and all is good. But...what was the point of the whole story? Why did you fight through hordes of enemies just to fight one thing? Video game villains are all different shapes and sizes, but there are some that stand out from others...
What makes a villain great though? What do they have to do to make defeating them worth it?
Video game villains don't always have to be the last boss in a game, but they have to have a certain impact, not only on the in-game character, but on you the player. The best villains from every game I have played have always triggered some kind of emotion from me that made me hate them more. Which, honestly, is a good thing: that means they did their job. Not all villains have to be hated, there were some villains that I actually liked and sometimes that made me want to be on their side. But the emotions caused by villains is what makes them great. Some villains are great throughout the entire campaign, but then they are a joke when you fight them and it makes you feel like all of this work and emotion was for nothing. This plays a big role in how the villain is presented because you build such anger toward them and then the moment you get to go 1v1 it doesn't have any impact whatsoever.
One particular villain that I hated personally, but at the same time admired how he was presented was Handsome Jack from "Borderlands 2." From the beginning he wanted to kill you and went through much to do so, and near the middle of the game he shot Roland (a playable character in "Borderlands" and the leader in "Borderlands 2") straight through the heart killing him instantly. He was about to attack your fortress and causes you to retreat. He had so many gimmicks throughout the entire campaign that it made you want to fight him more and more. Sadly he is the second to last boss and is a huge disappointment. He didn't put up any fight whatsoever and the fight just seemed like it wasn't thought of very much. It gave such a great villain such a lacking goodbye.
The actions of the villain also have to affect the gamer in some way. That's what sets apart a good game villain from a mundane one. Seeing villains in countless games just detracts from their value because if you've beaten them 20 times, what could they possibly do to stop you now? (I'm looking at you Bowser and Ganondorf!)
The good kind of villains really make a huge impact on the character and the game world itself. Being an antagonist that consistently gives your character trouble makes for a good villain, as long as those actions truly impact the character. Some examples are mortally wounding them, killing of a friend or significant other, or destroying their home. Some villains seem as though they are there for no reason or just seem to be the villain of the world. While some of those villains are good, I feel that if they had a personal connection of sorts with the main character that they make for a better villain overall.
In short; a good video game villain is one that impacts more than just the game itself, and one that consistently brings new scenarios to the table. Whether they are your best friend, your boss, or just some a$$**** that everyone hates, video game villains can make or break a game and deserve more attention when making a game.