Humans are classified largely by the planet they inhabit. Some, which dwell on very mild planets (reminiscent of Earth) can be reflected as any human in our reality. However, those that settled on much harsher planets, such as the largely unstable Furya, have evolved very unique characteristics absent in other renditions of humanity across the galaxy. That is to say, Furyans are much hardier, having been forced to adapt to the unforgiving climate and rigid landscape of their new "homeworld." That said, perhaps the most defining feature of Furyans are their incredible legacy as powerful, spiritual warriors.
Many months before Riddick was born, a powerful Necromonger commander, Zhylaw (who will later become the Lord Marshal seen in The Chronicles of Riddick feature film) leads an unrelenting genocidal assault on Furya in an attempt to void his fate divulged to him by an Elemental (a fate that dictated he would be killed by a young male Furyan). The genocide on Furya nearly extinguished all Furyan life. It was the belief of Zhylaw that the only remaining Furyans had been converted; that there were no survivors whatsoever. However, Riddick, and Shirah survive (Shirah's existence is relatively ambiguous). She often speaks to Riddick through some form of telepathic communication, though it is left unclear if Riddick is in congress with another surviving Furyan or a Furyan spirit. In either case, questions are raised as to how such a link is possible.
Following the events of The Chronicles of Riddick, Riddick is seated at the throne of Necromonger Empire, replacing the Lord Marshal as their iconic and religious leader (made possible through another Necromonger belief: "You keep what you kill." Though it seems odd that this belief would apply to not only one who is not a Necromonger, but one who is a sworn enemy of the Necromongers). This is not an isolated event, however, since the previous Lord Marshal awarded Riddick a knife he used to kill a loyal Necromonger. So perhaps this is such a deeply ingrained/indoctrinated belief that Necromongers dare not question it.
While not necessarily superhuman, Furyans themselves are impressive physical specimens; they are stronger, faster, tougher, more resistant to pain, more agile, possess acute senses, immense stamina, and recover quicker and with more finality than most of the other human races. Riddick himself has obtained what is called either "The Wrath of the Furyans," "The Race of Fury" (as stated by David Twohy) or "The Furyan Rage", which is essentially the collective anguish, pain, suffering, and anger of the billions of Furyans who didn't escape the Necromonger slaughter. He used it against Vaako and his hunting party of Necromonger soldiers. This phenomenon killed many of the soldiers, except Vaako and the Purifier (who also was a Furyan convert). Riddick also used this technique against Abbott and his fellow prison guards in Butcher Bay, after being interrogated.