A good villain is based on the concept for Blue and Orange morality. They are not inherently evil, but the path they have chosen is directly blocking the protagonists of the story. For example, an army general is not either an angel or a demon, but rather just a dude who wants to win this war for his country or return back home to his wife and kids. 

This is not to say you can't have a villain that is entirely evil; what would a villain be without evil? However, you've got to have the right motives. Perhaps he has to get something important back. Or maybe he's trying to save his family. All of that usually would be nice and all, except he's going the wrong way about it. Sending out his minions to sack villages, killing suspects, the usual evil stuff. Get what I'm sayin'?