Final answer:
The literary device in the sentence is a simile, which is used to compare the Red Death to a thief, highlighting its stealthy and unexpected nature.
Step-by-step explanation:
The literary device used in the sentence referring to the Red Death as 'coming like a thief in the night' is simile.
A simile is a figure of speech that compares two different things in an interesting way, typically using the words 'like' or 'as'.
In the provided sentence, the Red Death is compared to a thief using 'like', suggesting it arrives stealthily and unexpectedly, which enhances the suspense and theme of inevitable doom in the narrative.