Anton Chigurh — No Country For Old Men by Cormac McCarthyRead about another entry on the list.
Skills: Inescapable, relentless, and damn near indestructible. Able to withstand broken bones and other injuries that would bring down a normal guy. Enjoys and is good at his job, so that's, um, nice.
Dirty deeds: This cold-blooded assassin with "eyes like wet stones" digs killing people (mostly by smashing holes in their skulls with a captive bolt gun) so much that he has been known to take out the people who hire him. Chigurh ruthlessly exacts revenge on the world at large, taking lives with absolutely no remorse and sometimes determining whether or not to murder someone based on a coin toss.
Quote: "When I came into your life, your life was over."
No Country For Old Men is one of Elmore Leonard's ten favorite books.