Goblin

Diminutive, vicious, and thoroughly evil humanoid creatures with large bulbous heads, small eyes, and typically with olive drab to grey skin. These creatures prefer mountainous, hilly, forested and rough terrain for their lairs, as these are typically easier to hide from other races. They are prodigious diggers, carving warrens from hillsides, mountain slopes, and under the roots of trees.
They can call anywhere home, typically migrating in great numbers when they outgrow their current warren.