The Celestial Dragon-Flight is one of the many Dragon Flights in existence and also one of the oldest, second only to the Midnight Dragon-Flight in terms of age, power and sheer size - due to this they are revered amongst most dragonkin and are seldom seen by mortals.
Celestial Dragons tend to the multiverse itself, making them incredibly powerful but also neutral in regards to mortal races - they have seen the rise and fall of countless worlds and see mortal life as being somewhat below their concern: at the same time they can not allow vastly destructive entities such as Ebonscale or Kaosa disrupt the natural order and thus they have acted to limit the influence these beings have on reality.
Most prominent of which was when the Celestial Dragons formed a union with several other Dragon Flights to take down Ebonscale and weaken the monster sufficiently that he could no longer (in their eyes) endanger the universe.
The Celestial Dragons also had plans for Kaosa and her Twilight Dragon-Flight but decided not to risk another war between dragonkin and thus did not openly oppose her until much later - even then they would work largely in secret against the Twilight's influence.
In appearance the Celestial Dragons are pure silver, gold or bronze with eyes that can gaze into the past and future of any object - they can command the powers of space and time yet are the only dragon-flight that do not have wings, instead they opt for an appearance more like that of a stegosaurus, complete with the spiked back and tail: however they differ in the fact they have fairly long necks and can walk either on all fours on on their hindlegs.