Skaven
The Skaven are a race of humanoid rat-men, who inhabit the caves, tunnels, mines, and sewers of the realms. They control a vast Under-Empire of probably hundreds of Cities connected by tunnels created by the warpstone-based engines of the Skryre Clan. Little is known about the origins of the Skaven race. However, it is probable that they were created in an ancient city by a mysterious stranger who completed the unfinished temple of the gods and hung a great horned bell from the top of the tower. As the bell rang for the thirteenth time lightning lit up the sky and dark storm clouds gathered. As the weeks went on the rain never stopped and the vermin of the city grew bigger and bolder until they overwhelmed the inhabitants of the city.