Yellow dragon

From PathfinderWiki

Amateur scholars suggest that the presence of green dragons carries the implied existence of both blue and yellow dragons, in the same manner as mixing pigments of those colors creates the color green. However, there are no known yellow dragons, only tales of sightings across Avistan and Garund. The most prominent of those tales is the story of Kwislingyr, who in reality was a tarnished gold dragon whose corruption robbed him of his metallic luster.1