Kuo Toa

In ancient times, the kuo-toa inhabited the shores and islands of the upper world, but as humanity and those demihumans associated with them grew more numerous and powerful, they were slowly driven to more remote regions, taking refuge in sea caverns and subterranean waters. Some took refuge in the oceans, but these were mostly wiped out by aquatic predators, leaving the subterranean breeds to carry on as the last of their kind, prone to inbreeding and insanity. The word "goggler," once a racial epithet directed at kuo-toa, lost its meaning and became forgotten. The kuo-toa have not forgotten their old enemies, however. 
At the height of the illithid empire, the mind flayers captured kuo-toa by the thousands and forced them into bondage. The kuo-toa were unable to endure the oppressive mental force the illithids unleashed against them. By the time the mind flayers abandoned them, the prolonged psychic subjugation endured by the kuo-toa had shattered their minds.
The kuo-toa adopted a religious fervor, inventing gods to protect them against threats. Most notable of these threats are the drow, which have slain the kuo-toa on sight since the days when the two races first met.
God Makers. Kuo-toa worship gods of their own creation, but if enough kuo-toa believe that a god is real, the energy of their collective subconscious can cause that god to manifest as a physical entity. The form a kuo-toa god takes depends on the inspiration for its divine image, and is usually random or nonsensical.
One of the most revered gods of the kuo-toa is Blibdoolpoolp the Sea Mother, who takes the form of a female human with a crayfish head, a crayfish’s claws, and an articulated shell covering her shoulders. Blibdoolpoolp was likely invented by a kuo-toa that improved on a broken human statue by adding the limbs and head of a crustacean. In sudden awe of its handiwork, it then named the resulting form a god.
Kuo-toa that cross paths with an aboleth often find themselves worshiping it as a god, unaware to the fact that the aboleth is merely using them for its own nefarious ends.