Oh, well, if you want villainesses, Cruella deVille (from the book, not the movies) has everything you could want. Pyromania. Bizarre beauty. The desire to skin puppies. A tendency to drown cats. An unnatural attachment to fur.
For sheer versatility, I would like to propose Diana Wynne Jones's mother, whom she has credited as appearing in every one of her books as a villain. Once you know that, you start being able to pick her out, though she has greater or lesser degrees of evil, isn't always the primary antagonist, and takes different story roles, some of them benign in a weird way. Alas, too few people read Diana Wynne Jones.
For sheer perfection of banal evil, I give you the titular character of Jones's Aunt Maria (Black Maria in Britain), a sedentary and manipulative old woman who, confronted at the climax with a public revelation of all the harm she's done, including two deaths (one her own daughter), countless kidnappings, and decades-long incarcerations and transformations into animal shapes, responds by saying: "No, upon reflection, I have nothing in my life to reproach myself with, young man."
