What is up with the ending? William has been pursued by his shadowy doppelganger (ghostly double) across the world for years, and he finally kills him only to find that…he’s killed himself! Hmm.
Of course, if you’ve been paying attention, which we know you have, you’d have noticed more than a few hints that the second William Wilson might not be a real dude. All the strangely convenient similarities between them – the same name, the same birthday, same age, countenance, voice, arrival at school, departure from school – are rather suspicious. (Countenance means facial features.) And of course, the more that the narrator insists they are coincident, the more we suspect they are not. William also comments more than once on the fact that others seem not to notice their strange relationship – suggesting that, in fact, the second William is just a figment of his imagination. Notice that, after William is horrified by the countenance of his doppelganger at Dr. Bransby's school, he never again forces himself to look in the double’s face; the doppelganger is always masked or cloaked or hiding in the shadows.
All of these events hint to us that William Wilson #2 is some alter ego of William Wilson #1 – maybe his CONSCIENCE, as the epigraph so boldly suggests. If this is the case, what does it mean that William kills his double at the end of the story? As the doppelganger informs him:
"You have conquered, and I yield. Yet, henceforward art thou also dead—dead to the World, to Heaven and to Hope! In me didst thou exist—and, in my death, see by this image, which is thine own, how utterly thou hast murdered thyself." (last paragraph)
There are two basic ways of interpreting this. Number one is that William Wilson is speaking literally. When he stabbed his doppelganger, he literally stabbed himself – probably to stop himself from continuing to live a life of vice – and now he’s bleeding to death. If this is the case, his narration is taking place rather shortly after the stabbing incident, which is why the narrator claims in his introduction that death is approaching.
Option number two is that William Wilson the doppelganger is speaking metaphorically. Notice that he clarifies his use of the world “dead” – William isn’t dead TOTALLY, he’s just dead “to the World, to Heaven, and to Hope.” That is, his moral self is dead because he has murdered his conscience. What is left is a mere shell of man, hardly fit to be called a man, whose life can hardly be called living. The only sticky point in this interpretation is explaining why the narrator is so consumed with guilt in his introduction to the tale. If he just killed off his conscience and is a morality-free zone, shouldn’t he be off with Di Broglio’s wife rather than lamenting his sins?