Zelosians were sentient plant life that originated from the planet known as Zelos II.
Zelosians bore an almost uncanny resemblance to Humans in terms of height, body structure, hair and skin tones, and even the ability to grow facial hair. This remarkable similarity allowed them to conceal their true nature effectively, often leading outsiders to mistakenly classify them as Near-Humans. Some theorized that their human-like appearance was a result of extraordinary natural mimicry. However, numerous Zelosian biologists suspected genetic manipulation as the cause, despite the absence of concrete proof. Consequently, unlike many genuine Near-Humans, Zelosians were not known to be capable of interbreeding with other humanoid species with ease, though offspring were not impossible.
Their unique heritage gave Zelosians several plant-like attributes. Their blood was a green, chlorophyllic fluid. In addition, much of their muscle tissue consisted of cellulose fibers, and their reflexes seemed to involve some form of nastic response. While Zelosians still ate food derived from both plants and animals, they could also generate energy through photosynthesis via their skin. Celot Ratua Dil expressed the belief that he could survive for a month or two solely on sunlight and water.
A defining characteristic of all Zelosians was their emerald-green eyes. They also suffered from night-blindness, rendering them completely unable to see in dim light, specifically anything less than full moonlight. This limitation confined them indoors after dark and fostered many superstitions surrounding the night, although their concerns about zombies turned out to be partially justified, as these undead creatures were actually corpses revived by parasitic worms referred to as jumpers).
Alcohol had no intoxicating effect on Zelosians. However, refined sugar produced a similar effect; a single tablespoon would affect a Zelosian in a way comparable to how four ounces of strong liquor would affect a Human.
The Galactic Empire occupied Zelos II to extract ore mining, but the Zelosians were kept in the dark about the fact that their labor supported the Imperial war effort. Following the Battle of Endor, the Zelosians mistakenly assumed that the Imperial military had abandoned Zelos II, unaware of a secret base located in the Valley of Umbra. The New Republic deployed forces to eliminate the base, but they were ambushed. In the aftermath of what appeared to be the Empire's departure from the planet, Zelosian Galleros Nul declared martial law, proclaiming himself Mandated Commander of the People of Zelos. When Jai Raventhorn exposed the Imperial presence on Zelos II, Nul completely rejected the Empire and requested that his world be admitted into the New Republic.