Divine beings able to create and destroy worlds
"Dragons bless your path."
According to the creation myths of both Celestials and Demons, Dragons are the divine beings from a world known as Ekssar who embody the elements of magic and have created all of Existence, Caeles, Mors, and Aequus, with the sacrifice of their mother, the great goddess Tiamat. It is also believed that it was they who chose The Nine to defend Aequus during the Realm Wars, blessing them with great powers and the Elemental Stones.
After the Calamity, Humans assimilated this belief into most of their new religions, treating dragon as gods as well. One can only speculate how many of them there are, if there are only eight dragons each ruling over an element or if there is a whole society of dragons, how powerful they actually are, whether they can be contacted or not, what shapes they take, etc; and different religions believe in different sides of those matters.