Big Boil is a member of the free folk.
Big Boil has a boil on his arse, which he often complains about.
A Storm of Swords
Big Boil is one of the wildlings under Styr's command who passes the Wall to attack Castle Black from behind. During Summer's attack in Queenscrown, Big Boil is injured by the direwolf. During the attack on Castle Black, Big Boil is injured again and taken into custody by the Night's Watch.