The Chazrach, also called "reptoids," were a reptilian species of short, stout stature and flattened snouts. Originating from a galaxy far, far away, these sentient beings from beyond the galaxy were forced into servitude as slaves and soldiers by the Yuuzhan Vong.
Like their masters, the Yuuzhan Vong, the Chazrach were not originally from this galaxy. They were subjugated during the Yuuzhan Vong's expansion and conquest of their original galaxy. In contrast to the Yuuzhan Vong, the Chazrach possessed a connection to the Force.
For millennia—spanning thousands of years—the Chazrach were systematically bred in vast numbers to serve as disposable infantry. Each Chazrach had two dome-shaped calcifications protruding from their forehead, which suppressed their independence and allowed the Yuuzhan Vong to exert control over them. However, this control mechanism proved to be a vulnerability on the battlefield, as they could be easily neutralized. In combat, the Chazrach were directed by warbeasts such as Thrall herders and Rakamats. If a warbeast fell, the Chazrach under its command would indiscriminately attack any moving target, including each other.
The genetic manipulation carried out by the shaper caste eradicated any semblance of awareness or independent thought that the original species may have possessed. This deficiency, coupled with their diminutive and robust physique, rendered them incapable of effectively wielding the standard amphistaff used by the warrior caste as a whip. Instead, the reptoids employed the rigid coufee, which was better suited to their physical form, along with an inferior version of the amphistaff. A select few Chazrach demonstrated such exceptional service to the Yuuzhan Vong over generations that they were permitted to join the warrior caste at its lowest ranks.
Sometime in the distant past, the Yuuzhan Vong overpowered the Chazrach, initiating a breeding program to produce shock troops for their military campaigns. While not as powerful as the warrior caste, they proved to be unwavering and impervious to reason. They accompanied their masters aboard the worldships and later took part in the invasion of the galaxy.
The Battle of Dantooine marked one of the first significant engagements where the Chazrach were deployed, with the reptoids attacking New Republic forces stationed on the planet. However, the mental control exerted over the Chazrach was severed when Luke Skywalker eliminated the Thrall Herder, causing the creatures to revert to a feral state, attacking anything and everything in sight. Later, Commander Shedao Shai made use of Chazrach during the Battle of Ithor.
Reptoids were also present during the invasion of Rychel, where they engaged in combat with New Republic troopers. They also participated in the conquest of Coruscant, the capital of the New Republic.
Throughout the conflict, these beings remained loyal to their masters, defending the Yuuzhan Vong empire at the Battle of Yuuzhan'tar. It was here that the Yuuzhan Vong were ultimately defeated following the demise of Supreme Overlord Shimrra Jamaane.