Just some I liked:
Annie Wilkes, in "Misery".
Hans Landa, in "Inglorious Basterds"
Rebecca de Mornay, in "The hand that rocks the cradle".
Silva, in "Skyfall".
Anton Chigurh, in "No country for old men"
Caeser the Exterminator, in "Mousehunt".
Stansfield, in "Leon the Professional".
Thulsa...