Middle Earth/Sauron

Although never seen, Sauron has the biggest part in the ENTIRE book. All three books, in fact.

At first, we don't know too much about the origins of the [One Ring]?, but as the plot unravels, so do the plans of Sauron.

His army consists of hundreds of thousands of Orcs? with stronger, but not quite so many, evil human beings that have a need for power. The [Nine Ringwraiths]? are probably the strongest parts of his army.

He resides in [Barad Dur]? where he can watch all that goes on for thousands of miles with his [Evil Eye]?. He is one of the most cleverly thought-up villains of all time.