Thrall was the term given by the New Republic to those, usually Human, taken in to be Yuuzhan Vong slaves via surge-coral implantation. They were tall and fit, and had various amounts of coral growing out of their bodies to serve as natural weapons or defenses. Such coral outgrowths could include ridges to protect the eyes; spikes from the knuckles, elbows, and knees; limb and chest-plates; or even full-body stormtrooper-esque body armor. According to Kaye Galfridian, their feeling of pain is visible in their eyes.
They sometimes walked with the use of their knuckles. Although they let out war cries, they were more animal than sentient, not being on control of their actions according to Kaye Galfridian, being unable to use complicated weapons or tactics more advanced than basic cunning. In addition for use as soldiers, they were used to train Yuuzhan Vong warriors.
On occupied Garqi, the Garqi Agricultural University was a major center for Thrall production.
Master Shaper Nagme created an army of Thralls on Dibrook. She shaped her thralls to become stronger, more violent and ferocious and capable to breathe the Dibrook's air.
After the Yuuzhan Vong War, the thralls were not seen, but after the failure of the Ossus Project more than one hundred years later another type of surge-coral affected people appeared, and were called vongspawns.