In order that everyone contributing to the wiki is on the same page I have decided to lay out what types of attributes would lead to the classification of a character as a "Classic Villain".
First off, we should define what a villain is and then what the modifier "Classic" means for our purposes here. The term villain is used to describe a character in literature and other media is the opposite or nemesis or the hero. He is usually in conflict with the hero and can be used to illuminate or highlight the hero's strengths and weaknesses and to create tension and interest to the plot line. He can also be used for thematic development. The villain's character can be a caricature or cartoonish if painted with a broad brush or can be very subtle and so finely developed that it can be difficult to distinguish the villain from the hero. It should also be noted that the villains included in this wiki can be either fictional or real, living or dead.
The "Classic" term is meant to define our villains within certain bounds. One definition of the term classic is: a creation or work that is considered definitive; and, of lasting interest or significance. So we are seeking to further define our villains as one that is instantly recognizable and time-tested. Everyone can look at the villain and instantly recongnize them as such. We have somewhat arbitrarily decided that in order to qualify for "Classic" status our villain must have been created or existed for at least 25 years, or at least must have good attributes. This gives us a sense of lasting significance.
What attributes can we say are common in villains or reconizable as villainaous traits then? Here is a list of some of them. Our villain does not need to possess all or even most, but should have enough to qualify as villaiinaous. Some create villainy through combination with other traits and can also be found in the characters of heros.
There it is a short list of villainous qualities.