Cuaroc was a Dragon who existed as an Eldunarí during the reign of Galbatorix. Housed within a specially-constructed artificial body, he guarded the Vault of Souls under Vroengard. He bore the titles "Hunter of the Nïdhwal" and "Bane of the Urgals."
Cuaroc's artificial body was made out of a polished metallic substance and took the form of a large dragon-headed man. His chest and limbs were greatly muscled like those of a Kull and he wore no clothing except for a segmented loincloth made out of the same metal as his body. In his left hand he held a metal shield and in his right he held the iridescent sword of a Rider. His chest had a hidden latch which opened to reveal a purple Eldunarí, connected to thousands of silver wires.
It is possible that Cuaroc's artificial body was the most complex piece of machinery as of the present era, as it seems to resemble a magically-powered android-like body.
Cuaroc was originally a dragon and after his body was killed he continued to live inside of his Eldunari. He was given a new, artificial body created by Silvarí the Enchantress and was tasked with defending the Eldunarí against the threat of Galbatorix or any other such enemy. After Eragon took all but five of the Eldunarí, Cuaroc stayed behind to protect the eggs and remaining Eldunarí. After the fall of Galbatorix, Cuaroc went with Eragon, Blödhgarm, as well as a few other elves to find a new home for the eggs and Eldunarí outside of Alagaësia.