Dragons are immense, powerful, winged reptilian creatures, created from proto-dragons by the Titans to safeguard the world of Azeroth millennia ago. They are divided into several types called dragonflights. Since the fall of Deathwing, they have lost their titan-given powers as well as the ability to reproduce. They still remain powerful sorcerers however.
The proto-dragons were the ancestors of dragons before they evolved into the sapient, beautiful majestic creatures that they are known as today. Brann Bronzebeard recently uncovered evidence, corroborated by reports from adventurers in Deepholm, that proto-dragons and dragons may have originated from elemental drakes (i.e, stone dragons and storm dragons). Dragons share a common ancestry with both gryphons and wyverns, but it is unknown how far back they diverged.
Galakrond, a massive proto-dragon, is known as the “progenitor of dragonkind.” It is said that it is from Galakrond the titans created the Aspects, but this is a rumor the Aspects actively encouraged so as to keep the truth about Galakrond a secret from the dragonflights.