Primordial Titans

In a time long before men and elves, when magic was orders of magnitude more abundant, gargantuan beasts ruled over the youthful world. Dragons held domain over the sky; their lofty shadows falling on the mountain thrones of Giants, who ruled the vast swathes of land below. In the sea, great Leviathans controlled the icy, unfathomable depths.
For eons, this natural order went unopposed, though it was by no means a peaceful order. The three factions were constantly at war with one another, vying for influence in each other's domains. This proved exceptionally difficult for the Leviathans, who would come to be known as Aboleth. They could not match the raw strength presented by the giants and dragons and thus had to rely on their intelligence and beguiling influence to compete.
Ultimately, all three factions crumbled when the Great Diminishing occurred, reducing each to but a fraction of their power and influence. Though they have tried many times to regain their former glory, the world is intrinsically different now than the one that allowed them to reach such lofty heights eons ago. Should the world ever produce conditions sufficient for a return to such stature remains only an academic discussion for the time being...