Underworlders
Society is always about layers. Some people live above the issues that many others have to endure – despite the unfairness of it all. For a time, some declarations of rights pushed things in a positive direction and there was hope, but corruption ensured it could not be sustained and improvements did not last long.
As the Federation became more and more corrupt, ever-increasing numbers of people were left behind. Leftovers and castaways, they all ended with different solutions to their situation. A number accepted short duration, low paid contracts in order to survive, constantly moving from planet to planet.
Some ended up poor or in an even worse situation than when they started – yet they kept trying to make the best of the situation with their family. They accepted welcome package after welcome package from any corporation, switching from bonus to bonus. They were called Shims and were marginalized as profiteers. Shims move often as a family and are lower than middle class.
Others tried an independent life as a miner, explorer, or lone privateer accepting dangerous tasks. Many of these died with survivors often suffering from radiation damage and left forgotten on faraway planets. You will often see them with varied implants, using whatever leftover thing they find on space hulks to survive. They were called Clynosts.
But most chose to stay. They lived in bunkers, they lived in slums and they lived in secret subterranean cities. This is what we really call the Underworld. Underworlders (or unders or uwies) are mostly illegals and unregistered citizens, living beneath society in ignored secret layers of the very planets that the Federation cherishes the most.
They generally don't carry guns and don't threaten society but attempt to keep a low profile and simply carry on with their lives. They do hack a few supplies and sustain themselves off society's dregs, but have mostly built another sort of society of their own, trading service for service.
Underworlders are skilled in Stealth and Programming. They are also surprisingly skilled in defeating protections and defense programs similar to a small skill in Warfare. They of course reject Federal doctrines, meaning they have very low Federal Values.