An NPC class is a class held by a non player character. Most characters are not heroes. They do not spend their days battling monsters, searching for magic items, or blasting their enemies with spells; they plow farms, make shoes, and sell rope. Some are artisans, some are grand or petty nobles; but whatever the case, they do not possess heroic classes like arcanist or warrior. Instead, they have other classes. Some characters, particularly those who oppose or ally with heroes, are suitably villainous or heroic to warrant the use of the base classes. These are the classes for those who do not spend a lot of time adventuring.