They were all reptilian humanoids that were noted for their leathery skin with an average adult standing 1.8 meters tall. Sometimes these were covered in spikes and horns.

The species held a limited range of facial expressions because they lacked the necessary anatomical infrastructure. Most Nikto had cold black obsidian eyes. These were sometimes covered by a protective membrane. This took the form of a thin transparent pellicle that protected their eyes underwater and during windstorms.  As a result, they were noted for their "staring" eyes and a seemingly blank expression which led to many underestimating Nikto intelligence.

The Nikto species featured six distinct mutated sub-species due to massive radiation bursts from a dying nearby star M'dweshuu, which sped up the rate of mutation so that traits that normally took millions of years to occur instead took only thousands. The five sub-species inhabited different geographic areas of Kintan, developing unique adaptations to suit the different environments on the planet. Only five were known to the galaxy at large; the sixth, the Numol'elrul, were a water-breathing subspecies that lived in the caverns below Glussa Island but were considered nothing more than a legend to the others, as they cut off all contact with the rest of their species around 5000 BBY.

The varying appearance of the Nikto sub-species caused confusion amongst those who were unfamiliar with the Nikto, but all Nikto had certain similarities; leathery skin, sometimes covered with spikes or horns, as well as eyes that included a protective membrane to shield against Kintan's harsh environment.