Friedrich Schiller, Preface to The Robbers, 1781
Schiller knew already that there is nothing more boring than a simple all-black-villain. His choice of words may be a bit florid nowadays, but his idea is dead on. Don’t make your villain a flat copy of some random comic baddie. Give him some humanity. Same as the hero, the villain WANTS something. The difference is, he goes the wrong way about it. Makes questionable choices.