What do you call something that causes fear?
Example:
The wind and the owls weren't the/my only [...] that night.
I didn't using fear as a noun is a bit weird in this situation? What's a better alternative?
Using fear as a noun like this is perfectly acceptable. Most of the alternatives being suggested feel awkward in comparison. "My worst fear" and "my only fear" are common sentence fragments; google searches for them return 367k and 305k results respectively. Most tellingly) "the fear of" returns a whopping 47 million results.
You've already got the correct word - use it!
Fright may fit your context:
- Sudden intense fear, as of something immediately threatening
One option is Terror
- Informal. a person or thing that is especially annoying or unpleasant.
Even more so in British usage:
- A person or thing that inspires great dread
This fits pretty well into your sentence:
The wind and the owls weren't the only terror that night.
How about :
The wind and the owls weren't the only fearsome things that night.