The Khthon, a race of small, hairless humanoids, were native to the planet of Trieste. They looked perpetually old and wrinkled. They were a psychic race: able to foretell the future as well as to read the minds of all but strong-willed individuals. The Khthon also knew about the Yssgaroth, whom they called the Old Ones.
The Khthon had a primitive society until Trieste and the other planets in its system were colonised; the human settlers enslaved the weaker Khthons. When the Seven Planets became independent in 2396, the Khthons were given more rights but were still the lower class. They were presumably all killed when the Seven Planets were destroyed in 2400. (PROSE: The Pit)