It’s hard for me to pick one favorite anything , so I’ll go with my most recent fave: Madeline Usher in The Fall of the House of Usher. A lot of the credit goes to Mary McDonnell, who delivers every line with Bette Davis pomp and disdain.
Norman Stansfield and Oil Can Harry
Jean-Baptiste Emmanuel Zorg
The bad guys from Justified:
Boyd Crowder
Dewey Crowe
Dickie Bennett
Although, Dewey and Dickie were more bumbling than bad.
I very much enjoyed Andrew Scott’s version of Moriarty from the Sherlock series. Really well played and very finely attuned to be the foil / shadow of Benedict Cumberbatch’s version of Holmes.