Waterstone's in the U.K. has compiled a list of favourite literary villains.
"Villains are the more convincing and interesting characters."
Of the villains listed (and of those I'm familiar with), I feel the criminal of Suskind's Perfume is the one with the fullest, best-drawn character, and the one to whom I reacted most viscerally. (I'm racking my brain for villains they overlooked.)
There is a separate children's list.
For Britain's World Book Day a couple weeks back, The Independent published a list of of 100 favourite fictional characters chosen by 100 literary luminaries. (China Miéville chose Jane Eyre — who'd've guessed it?)
(Humbert Humbert makes both lists, and other villains also appear as all-time favourites.)
Thinking on this the last while, I've come to realize that I tend to read novels for ideas, then for story. Characters come after these.
After much agonizing I've determined my favourite to be Sara Crewe of A Little Princess, even though she is of "children's litereature." Then comes Larry of The Razor's Edge.
Who are your faves?