Okay so this is gonna be more of a speedy short article inspired by Mauser's question here on random. link Apparently people here have expectations and I won't fail lmao.

Above all else for a villain to be an effective character in my eyes is their backstory/motivation. Nothing makes a villain more fascinating to me than multiple layers. I'm talking about characters like (now I know you won't see this coming!) Azula and Regina. Regina is my prime example of a fleshed out villain. Her lover was killed when she was very young and right in front of her. That sparked her to start on the path to evil; she was desperate to bring him back. Another layer is added in season 2 when you see how actively she resisting the darkness and just how much manipulation and (from her mother) child abuse it took to get her over the edge. She's not just evil for the evils.
Azula is somewhat the same; on the surface it seems like nothing is really going wrong in Azula's life and that she pretty much just the antagonist because her dad said so. It's more than that though. Azula felt unloved by her own mother and so the only person she had to teach her morals was pops. And pops was an all out, full on asshole. Her complexity is sort of buried deep and at first was hard to pick out because she never made mention of it. When it was first mentioned she really glossed over it and made it seem like it was no big deal. At the very end of the show though, it all came out via a complete psychosis.

Which leads to the next point; if you throw on a sprinkle of crazy I'm more intrigued already. I think that that adds one of the critical multi-dimensions. A villain who isn't mentally sound can do some pretty wild things and create a lot of damage. Bellatrix is my bitch here; she's so delightfully sadistic and unpredictable. What makes her so effective as a villain is that her instability makes her creepy in a way that Azula's doesn't. Azula's makes her a sympathetic villain. Bella's makes her an effective villain. You don't know what's gonna happen with her and it keeps you on your toes.

The above mentioned; sympathy is another way to make a good villain. If you give them the right back story or motivation you can create a sympathetic villain. The kind of villain you almost want to agree with or at the very least, hug. Regina would be my biggest example of this. She has lost and been through so much.The woman really just wanted someone to love her and when she couldn't get it she tried to fill the void with vengeance and a false sense of happiness.This kind of villain evokes emotion and you almost want them to be redeemed, warm, and well-fed. Any character that can instill emotion is an effective character. Even if you don't like that character you'd have to admit that they're well written.

The next thing that makes a villain a good villain for me is the kind that keeps you guessing. If a villain can keep you on you toes through the whole show, book, or movie than he or she is doing a good job at being bad. Isabella (BBC's Robin Hood) is good for this. She started out as the good guy and turned evil. She's cunning and manipulative and constantly switched sides. You never really knew whose side she was actually on; the antagonist's or the protagonist's. Basically she did whatever benefited her at the time. She was that character you had to watch at all times lest you wind up with a knife in your back.

Which leads to the next component. Trickiness. A good villain is a smart villain. They don't kick the door in and yell, "LEEEEROY JENKINS!" They plan things and execute the plans well. They are smart and have the hero at a loss as to how to unravel their plan because the plan was so elaborate. Azula was extremely effective in this way; when she didn't have raw power on her side, she had cunning. She has a back up plan for going to the bathroom. I'm talking things like; in one episode she had no bending (her ability to wield fire). What she did instead was take a bunch of Dai Lee (yeah this is spelled wrong but fuck it, this is an article about villainy and my poor spelling is villainous). agents. These guys were earthbenders she had them lined up to protect her. What the heroes and the viewers don't find out until the very end is that she wasn't even trying at all; she was the decoy that wasted their time so they couldn't fight her father and in doing that--take down the Fire Nation. Add another layer of cunning on top of that because she had a wildly intelligent plan to have acquired the agents in the first place. With brains alone, Azula took down a city that hadn't been breached in nearly a hundred years. Literally it took patience and a clever disguise...and playing someone who was trying to play her. Like they were trying to stab each other in the back and she out stabbed him. So yeah, the more clever the villain the better.

Even if they aren't smart there's still a save. If they have wit and humor they can still be a good villain. Like Kronk from Emperor's New Groove. His head is a bit dull but he's a blast to watch. He's got a lot of hilarious lines and his screw ups a great to watch. This is the comic relief villain which can still be super effective if done right.

In other words there are many ways for a villain to be a good villain. They can have all or even just one of the above and I think that they'd be effective. I tend to favor the ones with all of the above the most. But lets be honest, I think for myself personally, all they have to do to be a good villain is be the villain at all lmao. I mean Icy from Winx is just an asshole. But I still love her.