"Good" Character: David Balfour (Kidnapped) ranks as one of my favorite "good" characters.  He is young and rather naive--trying desperately to be brave and manly in an extraordinary set of circumstances.  Even though his pride often stifles his better qualities, he always comes around in the end.

"Bad" character: The Joker (from the new movie Dark Knight) is without a doubt the villain of all villains.  He kills for the sake of killing, lies for the sake of lying, and tries to drag as many down with him as possible.  He seemingly lacks motivation, which cements him in my mind as a purely evil character.