X'rphan the White Wyrm

The Frost Dragon is a high-level monster from Sword Art Online. It can be found on Floor 55 deep within the West Mountain. It is said that to produce a rare mineral called Crystallite Ingot which is formed inside its body and can only be obtained with the presence of a master smith.

Sword Art Online
Kirito and Lisbeth attempted to obtain Crystallite Ingot to forge a new sword for Kirito, but the Frost Dragon proved to be quite difficult to handle with, and were both thrown inside its den too deep to escape. After spending the night together, they managed to find the mineral which turned out to be the dragon's excrement. When the dragon reappeared, Kirito and Lisbeth rode on its back to escape its den.