Accidental Aesop: The novel can be interpreted to teach that living a debauched life is self-destructive, even though Oscar Wilde meant for the book to have no moral.
Basil's assumptions about Dorian he told Harry in the beginning of a novel, and his behavior Retconned by Dorian - treating him with the jealousy only a lover would have the privilege for; accusing him of cruelly and intentionally playing with the feelingshe can't even know about; even complimenting him all the time which could easily make Dorian uncomfortable, weren't he blissfully ignorant; the Madonna-Whore Complex nature of his desire - though doesn't nullify his good intention, but his love doesn't come across as an idealizable one either.
Also Lord Henry. Was his corruption of Dorian a targeted attack on Dorian? Did he enjoy the results? Or was the outcome simply the result of his particulareccentricities? The novel tends to indicate he at least had intention, but whether the result was his intended outcome or not is up for debate.
Also regarding Lord Henry, there is the possible interpretation of him as being the Devil (being present when Dorian makes his "wish" that the painting would get old, influencing Dorian into hedonism, etc).
Angst? What Angst?: Dorian after Sybil's death. Then again, this is entirely the point.
Common Knowledge: It is a common belief that seeing his portrait would kill Dorian. In fact, Dorian in the novel goes to watch his portrait from time to time; it's when he tries to destroy it that he dies. The portrayal of Dorian in The League of Extraordinary Gentlemen helped to cement the misconception.
The Ho Yay in this book is so thick that it was actually used as evidence in a court case involving Wilde's sexuality.
It's heavily implied that various acquaintances of Dorian's, including Harry and Alan, are his current or former lovers.
The homoeroticism was more explicit in the original manuscript. Some more recent editions have restored it, adding deleted lines, and removing lines Wilde was forced to add to make the characters seem more heterosexual.
Anyone looking much younger than their age is often jokingly stated to have an "ugly portrait in their attic." (This joke is occasionally inverted, where a less-than-good-looking Acceptable Target is said to have "escaped from Dorian Gray's attic.")
Pictures of young handsome Dorian, and older-but-equally-handsome Dorian, have been used to parody the "This is him now—feel old yet?" meme.
Moe: Dorian, before going crazy. He starts out having a naive, childish personality that everyone around him becomes enamored with.
Moral Event Horizon: Pick from Dorian either driving his sort-of girlfriend Sybil Vane to suicide with a cruel Breaking Speech, and only feeling bad due to his own pride or stabbing Basil Hallward to death and then blackmailing his other former lover Alan into disposing of the corpse, which later drives Alan to kill himself too.
Narm: Dorian expecting the portrait to change back instantly only because he isthinkingof behaving more virtuously onwards. Even if the picture would have changed as he wanted, isn't it more logical to think it would have done so only after he had fulfilled his promise? Then again, it fits Dorian's staggering narcissism in that he believes that merely thinking about becoming better, and for selfish purposes at that, is on par with actually doing so and deserving of recognition. The painting itself mocks him, as the only change is a hypocritical smile forming on its lips.
Uniquely, occurring within the author's own writings — a lot of the famous quotes from Wilde's comedies come from the novel, and one of the major characters in Lady Windermere's Fan is an Ascended Extra mentioned in passing in the novel.
Also, Wilde's great uncle, Charles Maturin, wrote the novel Melmoth the Wanderer with the title character as a Flying Dutchman type who similarly keeps a portrait well-hidden, although not for Dorian's reason, only because it is dressed in antiquated clothing.
A meta-example is that the novel is somewhat inspired by the French book A Rebours, which is the "Yellow Book" Dorian is always reading.
The Penguin Classics edition's annotations note that the basis of the story, magical pictures that capture the soul or life essence of its subject's, is a very old trope indeed. The Picture of Dorian Gray was a grim twist and deconstruction of the magical portrait trope, which would have been well known to Wilde's audience at the time of its writing.
The topic of homosexuality— on the editor’s part, not the author’s. Wilde was forced to delete some more explicit references to it prior to publication, and add lines making the characters seem more heterosexual. Some more recent editions have restored his original intentions.
Mr. Isaacs's characterization as a Greedy Jew was particularly anti-Semitic even for its time.
It’s also mentioned in the first chapter that Lord Henry is smoking an opiate. This is barely remarked upon, though it might still establish his hedonism.
It’s also odd that there’d be so many people insisting on Dorian’s innocence, all because he’s pretty and blonde. Victorian society in the time period that the story takes place very much believed in Hair of Gold, Heart of Gold, and especially Beauty Equals Goodness.
Vindicated by History: The original novella version of the story was so poorly received that the magazine that printed it issued a recall for all copies of the issue, and the book version was both forcibly edited and largely ignored aside from scandals over its contents. Today it's considered one of the greats of Gothic horror.
The Woobie: Basil, who has to watch Dorian Gray, the love of his life and his greatest inspiration, descend deeper and deeper into corruption against his wishes and ultimately gets murdered by him. Even The Soulless Dorian felt sorry for him.
Adaptations
Ho Yay: The 1976 adaptation really plays up the homoerotic subtext between the male characters, especially the scene between Dorian and Alan Campbell, where Dorian is basically trying to seduce Alan into destroying the corpse.
Les Yay: This is possibly done in the teen horror novel "Mirror, Mirror", when Dore, the protagonist, is befriended by Luci, a new student. Younger readers may see this as nothing more than friendship, but given the Ho Yay in the original, this could also be a watered-down version of that.
◊ Even blaxploitation movie pimps would find that tacky and offensive.
