Sub-humans are creatures of the Hyborian Age, considered a sideline in the evolution of man. They appear almost human-like and above beasts, yet a with lower order of being than humans, failing to attain the level of morality or intelligence associated with normal human beings.
Conan faced a tribe of savage sub-humans in the icy lands of the Aesir, the frozen wastelands north of Cimmeria, where he saved a girl named Ilga, who was being attacked by them. He also encountered sub-human creatures who inhabited a cave close to the Vilayet Sea in Hyrkania.
In a cavern above a mountain pass near Zamora, Conan and Red Sonja encountered pale quasi-humans (also described as sub-humans) magically bred by the vampirish sorcerer Morophla. Sub-human creatures also inhabited the dungeons of Ravenguard in the Border Kingdoms.
The warlord Khalar Zym had some minions in his retinue who also were described as "sub-human", tall muscular men who had defaced themselves.