The Outsiders appear to categorise subjugated species in two ways: Vassal species and Thrall species.
Battle Thralls are species under the control of the Outsiders that are used as combatants and assault forces.
There are currently two known species classed as Battle Thralls.
The first has been named as the Children of the Sun, and are therapodian in physical appearance. They are not innately hostile and there is a slow but ongoing attempt at diplomacy. For more information about them, please check HELP CHILDREN OF THE SUN.
The second species has yet to be named, but use starships that are heavily armored and that require a physical assault in order to weaken it enough for conventional weapons to destroy the hull.
As of yet, it is unknown whether they would be open to communication with humanity.
