Zombie Dragon

'''"I thought there were few pleasures left in the world that I had not already experienced, certainly none that were worth expending any effort towards. I must confess, though, to the great thrill I felt when first I bound Agorak the Silent to my will. As delicious as it was, it paled in comparison to the joy I felt when I finally had the opportunity to unleash him on my enemies. Nothing quite like a Dragon to put fear into the hearts of Men. So much better if he's Undead!"

- Constatin von Carstein, Vampire Lord '''

Zombie Dragons are the reanimated corpses of once proud Dragons that were arisen from their resting place within the Plain of Bones by the use of powerful Dark Magic. The Plain of Bones is a harsh and lifeless landscape of multicolored sand and tainted rock located to the east of the World's Edge Mountains, from which protrude huge rib cages of ancient primeval Dragons. This is the place where Dragons of ancient times once came to die, to rest their bones amongst those of their ancestors as they had done for millions of years, before any other sentient beings walked the world.

Here lies the bones of the great ancestral Dragons: skulls the size of castle towers lie mingled with leg bones larger than the mast of an Imperial warship. These bones date from the ancients days of the draconic race. Though today's Dragons are of a lesser breed, they are still incomparably mightier than other races of the world. However, following the arrival of Chaos, the Plain of Bones have since become saturated with large amounts of Dark Magic. This magic eventually contaminated the remains of these Dragons, forcing them to rise once more as the first Zombie Dragons.

Ever since then, Vampires and powerful Necromancers of all kinds have been known to take a pilgrimage to this ancient landscape where they pick through one amongst many Dragon remains. Once he finds a suitable corpse, the Vampire or Necromancer who use the excess Dark Magic that contaminates the land to resurrect the Dragon back to life as his eternal combat mount. These once majestic creatures stagger upright once more with a great despairing roar before stooping to allow their new master to ride atop their powerful shoulders.

Animated by Dark Magic, a Zombie Dragon is borne aloft by great tattered wings, its body covered with thick, withered hide. Though in life it once breathed fire capable of melting steel, a Zombie Dragon can only belch forth a cloud of pestilent gas which strips flesh from bones and corrodes armor. A Zombie Dragon's claws and sword-like teeth remain as deadly as they ever were, and is still capable of ripping an armoured knight in half and swallowing his warhorse in one motion. When such a monster is used as a steed by a powerful Vampire Lord, even the greatest heroes quail before the raw might of undeath, for the combined might of Vampire and his Undead Dragon is enough to break the back of any army sent against them. Wreathed in a fog of rot and surrounded by swarms of blood-hungry flies, a Zombie Dragon can turn the tide of a battle purely by dint of its horrific presence.

Source

 * Warhammer Armies: Vampire Counts (8th Edition) -- pg. 49