"The Sniper" is a work of fiction and a short story. Beyond these obvious points, classification into subgenres becomes somewhat idiosyncratic. It is all too easy simply to take a theme, the setting, or some other aspect of the story and claim that this is a subgenre of fiction. Historical fiction is a widely recognized subgenre, and one might use it to describe "The Sniper," as the story is set during a clearly defined historical event. The action takes place in late June 1922 during the Battle of Dublin. This, however, was very recent history when "The Sniper" was written, since it was published only six months later, in January 1923.

Perhaps the best generic description of "The Sniper" is "suspense fiction," a genre which overlaps with many others, including mystery and horror. Suspense is one of the chief features of the story, since the protagonist is not only a dangerous man himself, but constantly in danger. He takes the risk of lighting a cigarette, and, almost immediately, a bullet hits the roof near him. Later, he runs across the street through a hail of bullets to discover the identity of the man he has killed. The author keeps up the suspense until the final sentence, making it the story's most prominent feature.