The mysterious doppelganger William Wilson haunts the narrator throughout his life, plaguing him with both their identical appearance and by ruining the narrator’s worst plans. The most common reading of the doppelganger Wilson is as a physical manifestation of the narrator’s conscience. When he sees Wilson’s face at the end, he realizes that it’s like looking into a mirror, emphasizing that they may be one and the same. Additionally, Wilson’s whispery voice may be a reference to the biblical “still small voice” (1 Kings 19:12), usually interpreted as the inner voice of conscience. The more leeway the narrator has to commit evil acts, the more Wilson steps in. At Dr. Bransby’s Academy, Wilson merely interferes with the narrator, allowing him to maintain complete dominion over all his classmates. During the debauchery at Eton, where the narrator engages in activity that is immoral but not violent against others, Wilson merely “sobers” him. But when the narrator targets a classmate to bankrupt him, Wilson reveals the scheme. Notably, Wilson appears to unmask the narrator’s cheating only after the narrator realizes that Glendinning has less money than he’d thought and begins to feel guilty. Wilson’s announcement ruins the narrator’s reputation but relieves this guilt.
However, it’s unclear whether the narrator’s split personality is indicative of the supernatural, or whether the doppelganger Wilson only exists in the narrator’s imagination. Considering the narrator’s desire to dominate and overmaster, to the point where he controls his parents from a young age, it’s entirely possible he has imagined his voice of conscience as an external force in an attempt to exorcize it. For all the space Wilson takes up in the narrator’s mind, his impact on the outside world seems small indeed. Critics have noted that the narrator’s peers don’t seem to notice Wilson: he speaks in a quiet voice, and he sleeps apart from other students, in a closet. This raises the question about whether Wilson truly exists outside the narrator’s imagination.