Having previously considered aspects of heroes and antiheroes, I was interested to come across some salient comments on villains in Chuck Klosterman's literary ode to that cultural and real world type. In his book of essays I Wear the Black Hat, he notes "in any situation, the villain is the person who knows the most but cares the least." This applies mainly to your master villains (say, Blofeld or Lex Luthor) and encompasses both the villain's key quality of lacking empathy and also that he has a level of superiority that makes him that much more threatening. It's interesting to note how well this applies to good fictional villains, but generally does not apply to real life villains. Most human beings have the benefit of caring about something other than themselves and most villains you're likely to run into in daily life -- a mugger or bully, for instance -- don't gain a sense of threat from their superior knowledge.
He expands his discussion in another essay, talking about a real person (D.B. Cooper) and commenting that "he should be a villain. But that overlooks the one intangible that makes Americans forgive everything else: superhuman self-assurance . . . Is there anything more attractive than a polite person with limitless self-belief?" What's most fascinating about this is that it is applicable in both real life and fiction and to both villains and heroes (it's a fitting description of, to name just two, James Bond and Superman), but also points up a great paradox in the human psyche. it makes no accounting whatsoever of either morality or motive, which both seem like they ought to be central arbiters of who and who is not, a villain.