Mul

From The unofficial Dark Sun wiki

The Mul is about the height of a tall human but with a very heavy bone structure, completely hairless and have a heavy bone ridge running down their forehead. The Mul is a cross-breed of human and dwarf. Very difficult to breed and very commonly is the death of the mother(human women always). Due to these reasons many mothers die before a living mul is born. Muls are sterile, always and also born as slaves. Muls often share the determination of their dwarven parents along with their increased strength and stamina but are often just as stubborn. According to Tim Brown, the word mul is pronounced exactly like the English word "mule".

Muls are bred for gladiatorial combat and slave labour.