Rifts - Pathway to Oblivion
Hector Skellian told stories of the interdimensional beings known as the splugorth, who are slavers, and power grabbers throughout the megaverse. He was discussing their practice of kidnapping humans and ogres to put magical tattoos on and use as warrior slaves, or sell as powerful muscle on their markets.
He told the story of how when Atlantis returned, a Splugorth known as Splynncryth took charge and turned it into his headquarters due to the power and efficiency present on Rifts Earth.
Nero Flashton was able to substantiate much of this when, after defeating the splugorth slaver barge and its entourage he informed the group that he was kidnapped by a splugorth, taken to another galaxy, had his implants put in, and an alien creature grafted to his chest as part of their Bio-Wizardry experiments.
Splugorth Slavers are known to roam the east coast of the old US looking for slave stock and testing the powers in the area.