Commoner: Coming from a humble background these are everyday folk, used to hardship and poverty. Generally has a profession and in smaller settlements might work for themselves or a merchant in larger towns and cities.
Squalid. You live in a leaky stable, a mud-floored hut just outside town, or a vermin-infested boarding house in the worst part of town. You have shelter from the elements, but you live in a desperate and violent Environment, in places rife with disease.
Monster. A monsterous enemy could be something as weak as a goblin to as powerful as a ancient dragon. They consist of monsterous races and creatures. They might have done battle with the creature, been robbed by it, wanting revenge, or hunting it.