Humanoids native to the planet Sullust, the Sullustans were distinguished by the two flaps of jowls around their cheeks, and large, mouse-like eyes that were typically dark and gleaming. They also had large ears. The species wore native headgear to cover their wide heads; at least one of these was modified for use as a flight helmet by the famous Sullustan Alliance and Resistance pilot Nien Nunb. The Sullustan language of Sullustese was a rapid chatter spoken in liquid tones.

Sullustans were a sophisticated species and lived in subterranean cities surrounded by lava.