The males of Sigma Draconis VI, who live a harsh Stone Age existence on the frozen surface while the women, the Eymorgs, dwell in comfort in a machine-run city below ground.
The Morgs are the male half of the humanoid population of Sigma Draconis VI. Their ancestors once belonged to an advanced civilisation, but after the planet fell into an ice age the sexes were separated: the women withdrew to an underground complex maintained by a great computer, while the men were left on the glaciated surface.
They appear in the Original Series episode Spock's Brain. A band of fur-clad Morgs ambushes the Enterprise landing party with clubs and stones. A captured Morg has no concept of women or companions and speaks fearfully of the others, the givers of pain and delight, who take men below to serve them.
At the end of the episode, with the Controller no longer served by Spock's brain, Kirk leaves the Eymorgs to learn to live alongside the Morgs on the surface.