Cthulhu and HP Lovecraft's mythos are a good example. There are horrific monsters that are worshiped as gods by mysterious cults. The ancient monsters of indescribable grotesque forms, with eyes and tendrils seemingly appearing from mottled flesh, worship and fear their own gods who are even more horrendous and incomprehensible, who they then even worship and fear even bigger, older and more obscure elder gods. Its the idea of the unknown being scary but what's beyond the unknown is even scarier.