They first appear in Las Paradiso, where they attempt to destroy Crypto and Pox, they are later seen at the Sunnywood stadium. Their technology is later encountered in Shen Long, and their source is located in Belleville. And finally, they are spotted on the Furon homeworld, where the final confrontation takes place.
There is three types of Nexos, each appearing at different events, and different places.
- Nexo Warriors - Alien cyborgs that were thought to be extinct years ago. Basic Nexos infantry, there are three different types, red the strongest, blue the weakest, and green the common foot soldiers. They are armed with a powerful phase cannon in their right arm, and use a small energy flail in close combat; they can also fire rockets at their enemies. The Red Nexos are the largest of the three and are located around the Fourth Ring of Furon, acting as law enforcement. Green and blue Nexos are encountered during missions and when the alert level is red.
- Nexo Walkers - Large walkers that are capable of great destruction of buildings. They are equipped with powerful lasers, missiles, and a diamond-hard exoskeleton. It can be destroyed by targeting the DNA collection recepticles between its hind legs.
- Nexo Saucers - These are saucers piloted by Nexos warriors, and are armed with twin energy cannons, that resemble Crypto's plasma cannons to some degree. They serve as the Nexos air force and will only attack while Crypto is piloting his Saucer.
Nexosporidium warriors are a race of cyborgs that were once thought to be extinct. Used as an army by the conspirators on the Furon Homeworld. Emperor Meningitis had them re-cloned for his serve as his own body guards. They serve as the main enemies for Path of the Furon.