What Makes A Good Villain

Gone are the days when villains could be evil just for the sake of it. Today's readers want complex villains with great backstories who they can love to hate. So what makes a great villain?
Some of my favorite villains are those that have tragic backstories, who were mistreated themselves or lost someone they loved. Rather than try to get help, they let their anger and grief consume them. They're better villains because you can almost understand why they turned to the dark side. You might even see yourself following the same path if you were in their position. Another recurring theme with villains is that they want to do something drastic, that will throw everything into chaos, but you do see their point.  They make a good point, they just lack the right execution. (Looking at you Marvel)
One of my all-time favorite villains is Regina or the Evil Queen from Once Upon A Time. She is complex, the daughter of a narcissist and she lost the man she loves at the hands of her own mother. She did not immediately become a villain, but that anger grew over time. It became more complicated because Regina loved her mother, and from a young age, she was told that what she was doing was for Regina's own good. Regina couldn't hate her mother, so she directed her anger toward Snow White. She then isolated herself, let jealousy get the better of her, and gave in to her dark magic. Her anger became a shield to hide behind and to protect her. Even later in the series, after she redeems herself, you can see her putting up that shield when upset. This makes her more sympathetic because her journey is long, but she wants to be a better person in the end for her child.
Many villains on TV shows are redeemed, usually by falling in love with the main character such as Spike or Damon. Redemption is a great theme in books, but it cannot happen overnight. You also need to balance out what that person has done as a villain and what they had done to redeem themselves. The scales will never balance of course, especially if they have killed people, but they can work toward their 'happy ending' by doing the right thing and letting go of their villain ways. 
When it comes to writing your villain, you need to have a good reason for their actions. People aren't born evil, events shape them. This could be loss, neglect, abuse, or simply being raised in an environment where it was expected of them. 
You need to understand what makes them tick, that way you can predict how they will react to a situation. A villain often comes from a similar background to the protagonist. They are two sides of the same coin, where one gave into darkness and the other finds the light. Do research into how a person reacts to a bad upbringing or abuse and this way you can accurately reflect this in the villain. Not everyone born into these circumstances becomes a bad person, but for those that do, there is usually a point of no return for them.
We like to cheer when the villain is killed, but when you give your villain depth, you often have mixed feelings over their demise. Yes, they did horrible things and they have to die. However, you can see that had circumstances been different, they could have been saved. This makes it all the more tragic.
When it comes to writing your villains, take the time to get them right. Give them good motivations for doing the things they do and don't forget to give them some good attributes too. Your villain may be the most horrible person on Earth, but that doesn't mean he still can't have a soft spot for animals! 
​Happy writing!