[quote=@Crimmy]
<Snipped quote by Lugubrious>

An antihero is a merely a protagonist who lacks conventional heroic qualities.
[/quote]

Still stealing my Skype quotes I see. 

EDIT: Should probably add that by the same token, an Anti-Villain is simply a Villain with heroic qualities and/or goals. So the either have evil goals with relatively moral means of achieving them, or good goals with brutal and evil means of achieving them.