Villians and heros

Recently I sat in a workshop and the exercise was to write an opening paragraph for a scene or novel. When we were done, we were to read it to our neighbor and discuss what kind of opening it was and why it worked or didn't work. I wrote the scene from my hero's point of view. When I read it to my neighbor, they loved it and thought he was an awesome villain. Hmmm, perhaps I had gone a bit too far on the bad-ass attitude. I didn't explain to them that this was my hero. The workshop went on, but I've thought long and hard on that moment.
Across genre's some of the best heroes have been villains and some of the best villains have been heroes.
What romance reader doesn't like a little bit of bad in their hero. Why? Because if he did everything the nice way there would be no tension. Without tension there is no conflict, no jazz, no thrill and no sex appeal.
What mystery reader doesn't like to pit their hero against the worst possible villain? Again, tension is built in when the worst possible-or alpha- villain is pitted against your protagonist. Who will win? Can you defeat someone smarter than you? What about someone crazier, or lacking moral direction, a loose cannon if you will?
Think of Heath Ledger's portrayal of the Joker in Batman. He didn't care about anything but chaos. Or Dexter- the serial killer who goes after serial killers.
As a writer we want to create characters that cause tension and excitement in our reader. A page turner is when the reader can't tell who is going to win in the end-even though they are within the "safe" confines of genre-where the detective brings the bad guy to justice and the hero and heroine have happy endings. If you can write a scene or story where the hero is pitted against a villain of equal or greater intelligence you've created a page turner that your reader will want to return to again and again.
Keep in mind that alpha villains don't have to be powerful men or wicked women. They can be as awful as a small girl with no remorse or empathy- think about the character of Briony in Atonement. The creepiest part of that whole story is that even though she had ruined lives there was no recognition of why it was wrong and no remorse.
So, who is your favorite villain in a book or movie and why? Who is your favorite hero and why? Do they have anything in common?
Cheers~