10. Karl Tanner
HBOHailing from Gin Alley in the slums of Kings Landing, Karl Tanner may not have the noble blood of some of the other entries on this list and all the castle forged steel and private lessons in swordsmanship that comes with it, but his tough upbringing arguably made him the intimidating warrior who we see overrun Crasters Keep. They say that iron sharpens iron and growing up in such an austere location during the reign of the Mad King must have been a character-hardening experience to say the least. Learning to fight in the tight, restrictive alleyways of Flea-Bottom meant that Karl became adept at using smaller weapons like daggers and knives as well as picking up a plethora of dirty fighting techniques which served him well over the years. The self-proclaimed fookin legend made a living for himself as an enforcer, assassin and general hired thug before eventually being caught and sent to the Wall. We see Tanner's true talent for murdering when the men of the Night's Watch attempt to liberate Craster's Keep from his control. In a one-on-one battle with Jon Snow he overwhelms the gifted swordsman and is on the verge of adding the bastard son of Eddard Stark to the long list of men and women he has killed before some external influence evens the odds.