His world is not the unknown, but that irrational horror: the unknowable.
His invisible mental currents reached for the unknown horror and held it tightly.
Like all unknown horrors, it's deeply attractive and terrifying at the same time.
Suppose you discover some entirely new unknown horror from your people's past.
It was a race with unknown horror.
Its lighting had brought home to him, and everyone else, that they really were on their way down to the unknown horrors of the Pit.
He watched the brown fabric of his clothes as if it were a curtain, about to open upon unknown but certain horror.
The thick walls afforded some sense of protection from the unknown horror that lurked beyond the light.
The warriors, keyed up for a fight or to face some unknown horror, began to chuckle.
This time she had to go beyond the screams, to find the unknown horror at the heart of their pain and fear.