Best? I'll be a little different and say Lord High Chancellor Adam Sutler,
not to mention his amoral right-hand-man Mr. Creedy, in V for Vendetta.
I love John Hurt's performance. He commands the screen even though he doesn't do much besides appear on a giant viewscreen and bark orders to his underlings. Still, it's John-fucking-Hurt!
For worst, what about the smarmy corporate guy in Superman III
? Imagine all the camp of 1970s Lex Luthor but without Gene Hackman's charm.
Dominic Purcell's version of Dracula in Blade Trinity
is both one of the worst comic book movies ever and one of the worst Draculas ever (tied with Richard Roxburgh's godawful whiner in Van Helsing