An eldritch concept embodying the unknown. Common motifs include, but are not limited to: the unexplored, the dark and shadows, order and disorder, uncertainty, otherness, a loss of humanity, off-putting sensations, strangers, botany, instability, and suggestive romantic themes.

The most common portrayals are The Nightlanders, beings that look like shadows; the Smiling Man, a being with a too wide smile and "wrong" eyes that stalks and kills people; and The Ivory Woman, a chalk-like being that creates and manipulates accidents and uncertainty. When written as a Fear, The Deep, a being that may not even exist, has also be portrayed as this.

Portrayals of the Fear of the Unknown: