Flashman: the great character creation of George MacDonald Fraser. Utterly reprehensible (coward, womaniser, etc.) but don't you just see yourself in him and wish for just a touch of his luck?
Lockhart Flawse (aka 'The Bastard'): the wonderfully dark and sardonically comic hero of Tom Sharpe's 'The Throwback. better even than Wilt.
Griffin: 'The Invisible Man' ... paranoia personified.
Meursault: the lead in Camus 'L'Etranger' and literature's most compelling psychotic.
Moriarty: Sherlock's bete noir and a villain to admire (tho' not evil enough in my opinion).
Alex: from the masterpiece that is 'A Clockwork Orange' ... brilliant, brilliant, brilliant. Funny evil and profound with it. the Droogs' patois is inspired.
O'Brien: the dark presence in '1984', the greatest book I've ever read. The fact that the political treatise Orwell puts in the middle is genius and gives me hope that my own 'Confusionism' tract won't be edited out of 'The Demi-Monde: Summer'.
And the winner is ... Alex! (by a nose ahead of O'Brien).