Aboleths

Before the coming of the gods, aboleths lurked in primordial oceans and underground lakes. They reached out with their minds and seized control of the burgeoning life-forms of the mortal realm, making those creatures their slaves. Their dominance made them like gods. Then the true gods appeared, smashing the aboleths’ empire and freeing their slaves. Aboleths have never forgotten.
Aboleths have flawless memories. They pass on their knowledge and experience from generation to generation. Thus, the injury of their defeat by the gods remains perfectly preserved in their minds. Aboleths’ minds are treasure troves of ancient lore, recalling moments from prehistory with perfect clarity. They plot patiently and intricately across eons. Few creatures can conceive of the extent of an aboleth’s plan.
Aboleths dwell in watery environments, including ocean abysses, deep lakes, and the Elemental Plane of Water. In these domains and the lands that adjoin them, aboleths are like gods, demanding worship and obedience from their subjects. When they consume other creatures, aboleths add the knowledge and experiences of their prey to their eternal memories. Aboleths use their telepathic powers to read the minds of creatures and know their desires. An aboleth uses this knowledge to gain a creature’s loyalty, promising to fulfill such wants in exchange for obedience. Within its lair, the aboleth can further use its powers to override senses, granting creatures, such as its followers, the illusion of promised rewards.
Enemies of the Gods. The aboleths’ fall from power is written in stark clarity on their flawless memories, for aboleths never truly die. If an aboleth’s body is destroyed, its spirit returns to the Elemental Plane of Water, where a new body coalesces for it over days or months.
Ultimately, aboleths dream of overthrowing the gods and regaining control of the world. Aboleths have had untold eons to plot and to prepare their plans for perfect execution.