Cold-drakes

Not every dragon breathes fire. The cold-drakes are the lesser kind, lacking the flame of Glaurung or Smaug, and they make up the difference with iron hard scales, wicked claws, a tail heavy enough to break a man and a breath of cold that freezes what it touches and puts terror into whatever hears them coming. Morgoth bred them in the north in the closing years of the First Age. When that age ended, some went east and settled in the Northern Waste, the Grey Mountains and the Withered Heath, where the cold suits them and there was room to multiply. Over the ages that followed they became the standing danger of the northern ranges, and the Dwarves who mined there paid the price of it.