According to the American Heritage College Dictionary, an interloper is a trespasser, a person who intrudes in a place or situation. An interloper is also a meddler in the affairs of others.
In Saki's short story entitled "The Interlopers," Ulrich von Gradwitz patrols the dark forest one night in search of his enemy. He considers Georg Znaeym an interloper, a trespasser and "game-snatcher" on his "narrow strip of precipitous woodland" that has been reclaimed from the illegal possession of the Znaeym family "in a famous lawsuit." There is strong animosity between the two men, but when they suddenly confront each other as they each come around the trunk of a huge beech tree, they hesitate in a civilized moment before firing their rifles at each other. In that instant, lightning strikes the tree, and the men are pinioned beneath a tangle of branches.
Although not fatally injured, the two men are exasperated that they are trapped together. Each curses the other and adds insults, describing what his men will do to the other when they arrive. After some time, though, the two men reconcile with one another because they realize the folly of their animosity. Graciously, one tells the other than when his men come, he will have them aid the other. However, in another twist of fortune, there are new interlopers. In the "chattering laugh of a man unstrung with hideous fear," Ulrich von Gradwitz tells Znaeym that these new interlopers are wolves.