Wyvern

The Dragon (unofficial) also known as the Grimm Dragon is a titanic flying Creature of Grimm that is capable of summoning other Grimm.

After Ruby unleashes her power in "End of the Beginning", the dragon was frozen to the top of Beacon Tower, unable to move.

Appearance
The Dragon is an enormous winged creature, with large red bat-like wings, a pair of legs and a tail. The red membrane of the wing is translucent. It has rough black skin, with white bone-like spines along its body, including an external skull, rib cage and rows of dorsal spikes.

It also has three bony spikes on its tail and large claws on its hind legs. Its skull has a pair of large prominent horns and six yellow-red eyes. Its jaw has teeth extending down along the creature's neck, beyond its skull, such that its entire neck also opens when it roars.

History
The beast was apparently laying dormant within a mountaintop near Mountain Glenn for an unspecified period of time. During the massive Grimm invasion of Vale in "Battle of Beacon", amidst the chaos and destruction unfolding within the city, the Dragon awakens beneath the mountain and smashes its way out, causing the ground to tremble. The beast then takes to the air and heads towards Beacon Academy, summoning lesser Grimm in its wake.

Cinder Fall apparently foresaw the awakening of the Dragon and tells Mercury Black to make sure that he films and broadcasts its arrival. When it awakens, Glynda Goodwitch softly murmurs in horror while Professor Ozpin reservedly watches its approach.

In "Heroes and Monsters" and "End of the Beginning", the Dragon appears to be transfixed to the Beacon Tower, circling around it repeatedly. Cinder ascends to the top of the tower and begins communicating with the Dragon. She makes eye contact with it and tells it that Beacon is its home now. However, Cinder is interrupted by Pyrrha Nikos, who attempts to stop her. During their fight, the Dragon and Cinder destroy the top of Beacon Tower, disabling the Cross Continental Transmit System. After witnessing Cinder killing Pyrrha, Ruby Rose unleashes a tremendous power in grief. A blinding white light envelops the Dragon, which seemingly "freezes" it in its place, perched on the side of the tower.

Although frozen, the Dragon remains alive and continues to attract more Grimm to what remains of Beacon. Its enormous inert body is still fully visible from Vale.

Abilities and Powers
Although it has yet to be seen in combat, it is clear that the Dragon is enormous and capable of flight despite its size. Uniquely, it has the ability to summon other Grimm: the creature exudes a black, incredibly viscous tar-like substance from the skin all over its body. When droplets of this substance impact the ground, lesser forms of Grimm are summoned from the residue. Types of Grimm which have been seen summoned in this manner include Creeps, Beowolves and Ursai.

Trivia

 * Dragons are a mythical winged reptilian creature present in many cultures. As the Grimm Dragon has two legs with its front arms attached to its wings, it could be classified as a wyvern, a creature usually considered a subspecies or relative to the dragon. However, it should be noted that there is no standard description for what is a Dragon and what is a Wyvern; it is entirely up to the decisions of the creators.
 * The Dragon was designed by production/concept artist Erin Winn.
 * On the Volume 3 commentaries, the Dragon's ability to summon Grimm from the liquid that leaks off it is described as a sneak peek towards the origin of the Grimm.