Although The Picture of Dorian Gray deceptively begins as a novel of manners with satirical and witty dialogue from Lord Henry, it takes a dark turn and ends up incorporating many Gothic elements. Specifically, a curse, supernatural elements, a Byronic hero, a hidden chamber, and horrific crimes lend a Gothic feel to the novel.
The curse takes a surprising form in this novel. Rather than being a familial curse that plagues the main character, the curse comes out of Dorian's own mouth as a fleeting wish. He states that he wishes the portrait would grow old and ugly but that he would always remain as youthful as the painting looks now. As he utters the wish, he makes a Faustian bargain, declaring that he would give his soul for such an outcome. Ironically, he does just that. The wish that turns to a curse and the Faustian bargain are darkly Gothic.
Obviously, the novel incorporates the supernatural. The fact that the painting ages but Dorian doesn't is an impossibility that requires the intervention of supernatural forces—forces that are never explained in the novel. This reliance on the supernatural is representative of Gothic literature.
Dorian Gray qualifies as a Byronic hero, a figure that populates many Gothic novels. Like other Gothic heroes, Gray is capable of great evil. His passions exceed those of normal men. He is attractive to others, whom he treats cruelly. He harbors a secret, deep guilt that torments him from causing Sybil's suicide and from various other acts of selfishness and murder.
What's a Gothic novel without a secret room, forbidden wing, or hidden chamber? In Wilde's novel, the portrait is hidden away in a closet in Dorian's chamber where no one can see it but him.
Finally, Dorian's hedonistic lifestyle and shameless crimes bring out the horror factor that is typical of Gothic literature. His murder of Basil Hallward, who has only tried to befriend and advise him, is particularly shocking. The final scene of his attempt to "kill" the painting, which results in his own death, is a wonderfully Gothic scene, incorporating gruesome violence with the supernatural.
Wilde turns what appears at first to be a novel of manners into a Gothic novel by his use of several techniques that are characteristic of the Gothic genre.