Grey Ghost
From A Wiki of Ice and Fire
Grey Ghost was a wild dragon that dwelt in a smoking vent high on the desolate eastern side of the volcano called Dragonmont. He was named by Dragonstone's smallfolk. He was never claimed nor ridden by any man, living or dead.
Description
He was a pale grey-white, the colour of morning mist.
About
He was a nobly shy dragon who avoided men and their works for years at a time. He preferred to feed on fish and was often glimpsed flying low over the narrow sea, snatching prey from the waters. Some of the dragonseeds sought the Grey Ghost but could not find him as he was ever an elusive creature.
Grey Ghost was killed and partially devoured by Sunfyre upon his return to Dragonstone.