The Battle Thralls of the Ur-Quan Hierarchy are the species who have pledged to serve the Ur-Quan Kzer-Za by helping them enslave other sentient races. Their duties include providing military support for the Kzer-Za and watching over slave shielded worlds while their masters pursue more important matters.
Battle Thralls have rights to travel through space and to retain some autonomy on their homeworlds. It is likely that their goverments are chosen by the Kzer-Za.
They are not allowed to make war on other Thralls or "fallow" slave species. Punishment ranges from blasting villages and cities to total annihilation, depending on the severity of the crime.
- The Androsynth, although they were destoyed before the Second War began in ernest.
- The Ilwrath
- The Mycon, the only race to seek out the Ur-Quan, rather than waiting to be defeated by them.
- The Spathi, who intended to become a fallow-species, but were pranked by the Umgah.
- The Thraddash, conqured before the First War, but were left to "guard the rear" and did not participate in it directly.
- The Umgah, the first race conqured by the Ur-Quan at the start of the First War.
- The VUX
- The Yehat, the only former Alliance member to choose Thralldom upon defeat.