The Umbarans were a slender near-human species with pale, bluish skin. They had four limbs: two legs, and two arms with five-fingered hands. They had opposable thumbs, essential for throwing, gripping, and the use of tools. Umbarans had gaunt, emaciated faces with gray markings around the sockets of their colorless eyes. They had a single heart, the stabbing of which was a fatal injury. Although Umbarans did have hair,some of them either were bald or shaved their heads. Because of the species’ skill at manipulating others, there were rumors that Umbarans had the ability to control minds. With their colorless eyes, they were capable of seeing in the ultraviolet spectrum.

On their gloomy homeworld of Umbara, the so-called Shadow People formed an organized society divided into castes, and they constantly schemed to improve their social rank. Their technology was more advanced than that found in most of the galaxy. Though Umbarans were capable of speaking Galactic Basic Standard, on their homeworld they primarily communicated in their native language, which had an alphabet that consisted of twenty-six letters. A traditional Umbaran garment was the voluminous shadow cloak.