Winthrop said:
Okay, so I haven't gotten around to Korra yet, but I just watched the original series a few months ago for the first time, and this article states that The Last Airbender didn't have a sympathetic villain and everyone seems to be agreeing with this notion and just debating whether or not Korra's are deeper than that, and they are right that Ozai wasn't sympathetic. But maybe people are forgetting that for a large part of the series Zuko and Iroh are villains and they are incredibly sympathetic and relatable. Sure I wouldn't call them evil, but they ARE working for an evil nation and trying to complete unfinished genocide and kill the world's only hope for personal gain. I could see where someone would argue that they aren't the main villain because Ozai is the one responsible for all the destruction and because they eventually become good, but in a sense those same comments could be made about Darth Vader. While they aren't the greatest evil in the world or Aang's greatest enemy, they get by far the most screen time and have the more direct and personal conflict with Aang.
Even if you want to bar those two on the ground that eventually they become good guys, Azulla is still a bit sympathetic once she goes nuts. Shes still behaving in an evil way, but the fact that the realization that even her own closest friends didn't love her clearly troubled her in a very human way. I think that saying the Last Airbender had unsympathetic villains without considering those characters and looking at Ozai is silly, because Ozai essentially has no personality and was just a force of nature in the background for most of the series.
Zuko and Iroh are not villains, they are antagonists. A villain is someone the protagonists actively oppose and try to hinder/stop, an antagonist is someone who actively opposes the protagonists and tries to hinder/stop them. Most of the time the two are the same, but not necessarily.
For example, in the ATLA series, Zuko and Iroh are antagonists in Season One and even Two. They try to apprehend Aang (well, technically only Zuko wants to, but that's beside the point) but the protagonists don't try to stop
them. Then they turn protagonists in Season Three.
Ozai on the other hand is a villain who tries to remake the world in his image and thus the Avatar and gang actively opposes him from Season One, by collecting information, training and collecting allies. However he is not an antagonist until the last few episodes, since he doesn't oppose the protagonists directly, only by proxy and influence.
Then there is Azula, who starts out as an antagonist that wants to take down the protagonists directly and then becomes a villain by the end of Season Three when Zuko and Katara personally have to oppose her and take her down.
I'm just telling you this because correct usage of this terminology is kind of important when we are talking about fiction.
[Edit]: Actually, villainy and protagonism-antagonism work on two separate scales, but I don't have the time to get into that in detail right now. Maybe once I'm home from work...