Out of the Abyss
A degenerate fishlike humanoid race that once inhabited the shores and islands of the surface world.
Their societies have a theocratic structure, meaning that they are ruled over by their archpriests. Any archpriest of a specific Kuo-Toa domain demands that all of its subjects worship a specific god. The archpriest’s mad belief in its god is so fervent that it manifests the powers of a high cleric.