The Underworld is home to those who have no place in the World Above. The tunnels and caverns are filled with a surprisingly large population, most of whom live out their lives without ever seeing the sun. The population is divided into groupings known as Breeds. Some Breeds are true species unto themselves, but most are merely convenient labels for similar individuals. There are seven Breeds that make up the population of the Underworld. Each Breed is fully described below.