Content Warning: This section contains references to addiction and child abuse.   

The monkey’s defining feature is its malevolence; even before it kills anyone, it elicits a vague “disgust” in Hal Shelburn, though this does not override his simultaneous attraction to the toy. The toy is a supernatural and apparently motiveless embodiment of evil, killing at random and exerting a sinister influence over characters like Hal and Petey. Yet the monkey is not purely an abstraction; through it, Stephen King explores more everyday manifestations of evil, ultimately suggesting that much evil is cyclical, automatic, and acquired rather than innate.

The nature of evil arises as an explicit concern toward the story’s conclusion. Struggling to explain the toy to his son, Hal reflects:

Somewhere along the line—perhaps even in the dark back closet of the house in Connecticut where the two boys had begun their growing up—something had happened to the monkey. Something bad. It might be, […] that some bad things—maybe even most bad things—weren’t even really awake and aware of what they were. […] [M]ost evil might be very much like a monkey full of clockwork that you wind up; the clockwork turns, the cymbals begin to beat, the teeth grin, the stupid glass eyes laugh (188).