Whilst information is scarce on Crom Cruach, it is suspected to manifest as some kind of cyclopean serpent or annelid, although as with all of its kind, it is sure to bear no more than a passing resemblance to such animals.
An ancient deity mentioned in an English translation of the Necronomicon who was worshiped in pre-Christian Europe, particularly in Celtic Ireland, those who sacrificed to the Bloody Crooked One were given the title Master of the Runes. It is said to lie dormant beneath the prehistoric megaliths known today as Stonehenge.
- Crom Cruach in the Cthulhu Mythos was inspired by the actual worship of a god of the same name in ancient Britain.
- The Door to Saturn (1932), by Clark Ashton Smith.
- Wilbur Whateley Waiting (1987), by Robert M. Price.