White dragons are a type of dragon created from the Queen Black Dragon's eggs mixed with Kerapac's blood that were hunted to near-extinction in the Third Age to make Third-age ranger armour, which is made out of white dragonhide. White dragons are imbued with a type of magic that allows them to travel between different planes simply by flying, and their kind also showed a lack of the aggressiveness found in the other types of dragons. To travel between different realms of existence, white dragons cut open small portals that allow them to fly through the Abyss to other worlds.
During One of a Kind, it is revealed that only one white dragon remains, named Therragorn. She was hidden in a dungeon underneath the Wilderness by the King Black Dragon to protect her from dragon hunters, which come to kill her soon after her location is revealed.
In addition, the Queen Black Dragon tells the player and Hannibus that the Dragonkin took white dragons and imbued them with Abyssal magics, which eventually drove the dragons completely mad. The dragons were changed into a completely different species, celestial dragons, as a direct result of the Dragonkin's experiments.