The narrator is an anonymous resident of Charleston who befriends Mr. William Legrand by accident. He is a rational, educated man who exhibits genuine concern for his friend's well-being. He frequently observes events with a skeptical eye, quick to fear that Legrand suffers from a mental illness when presented with bizarre behavior regarding the golden beetle.

Mr. William Legrand is a well-educated man from an ancient Huguenot family in New Orleans. Following a series of financial misfortunes, he relocates to the wilderness of Sullivan's Island to escape the shame of his poverty. He demonstrates high intelligence and experiences severe mood swings, alternating between intense enthusiasm and deep melancholy. His discovery of a strange scarabaeus beetle sets off a chain of mysterious actions that alarm his associates.

Jupiter is an emancipated Black man who refuses to leave the service of his former enslaver. He is deeply superstitious and fiercely protective of Mr. William Legrand, frequently worrying about his employer's physical and mental health. He distrusts the newly discovered gold bug, firmly believing it has supernatural properties that make Legrand sick.

Lieutenant G is a military officer stationed at a fort near Sullivan's Island. He briefly takes possession of the gold bug after Mr. William Legrand finds it. His possession of the beetle forces Legrand to draw a picture of it, which accidentally sets a larger mystery into motion.