The Thomas Covenant
series by Stephen Donaldson? The protagonist isn't evil
, per se, but he's definitely an anti-hero. When discussing the series, it would not be uncommon to hear him referred to as an asshole leper rapist.
I've never read them, but Michael Moorcock's Elric
series might fit the bill.
The Lies of Locke Lamora
by Scott Lynch features a gang of thieves and con artists as the protagonists. They're essentially good at heart, so may not be what you're looking for. Excellent, though. The Gentlemen Bastards
is the name of the series.
George R. R. Martin's A Song of Ice and Fire
series is certainly filled with despicable characters.