Throxillian

The Throxillian people were a race of interstellar explorers in the far future of human history.

Throxillian explorers had given the Cimmerian System its name after noting its lack of a visible sun. The Eighth Doctor encountered a group of Throxillians in a base on Cimmeria IV as they were rigging up a set of artificial suns around the planet. (AUDIO: Embrace the Darkness)

Society
Indications were that Throxillian space exploration was handled by private companies looking out after their own interests. Interstellar outposts were company property and the companies flew their own set of rescue ships to safeguard them. Company personnel worked under a ranking system, though whether military or managerial is unclear. (AUDIO: Embrace the Darkness)

Behind the scenes
The original script for Embrace the Darkness had been written with the Morestrans in mind, but the producers could not secure the license, so the Throxillian name was used instead.