!! The book provides examples of:
* AlternativeCharacterInterpretation: Not a full example as this is actually mused upon in the book, but the idea that the serum doesn't actually transform Jekyll into a different-looking evil man, it simply transforms him into a different-looking man, and it's the intoxication of being able to get away with any crime that leads him to act so evilly.
** Of course many adaptations, especially recent ones, decide to eschew the idea that it changes his looks at all and represent the changes purely by acting.
** In the book Jekyll pretty much admits that his motive for inventing the serum was nothing other than ForTheEvulz; he wants to be able to act immorally, but as Jekyll he'll always be worried about his respectable image (not really anything to do with conscience). As Hyde he doesn't have to worry, as the worst people think of him is that Hyde might be blackmailing him (and / or could be his BastardBastard son). He never, ever expresses remorse for anything Hyde does; he only bemoans that when Hyde goes too far, they both might get caught.
* CommonKnowledge: As noted in the intro, there are ''many'' common misconceptions about the novel.
* HoYay: Too easy to read some Utterson/Jekyll into the former's concern for the latter.
** His fears that Hyde was Jekyll's lover, and was using that to blackmail him.
*** Homosexual undertones were read into the book early on, and a few of Stevenson's gay friends chided him for possibly bringing them to light at all. The recent passing of homosexual legislation up north meant that closeted homosexuality wasn't just a hot-button issue at the time, but that Stevenson could possibly have had it on the mind while writing. A closer look at the edits from the second manuscript seems to support this theory, as Utterson himself starts to read a little bit more into Jekyll and Hyde's perceived relationship. Then again, this was a time when two men could have a completely platonic [[RomanticTwoGirlFriendship Romantic Two-Man Friendship]] and not be chided for it (again, because the idea of two men having sex with each other was just too absurd for Victorian sensibilities).
*** A short story by Creator/KimNewman, "Further Developments in the Strange Case of Dr. Jekyll and Mr. Hyde", riffs on this; [[spoiler: Essentially, Hyde is a separate person. And he's Jekyll's lover.]]
* ItWasHisSled: In a ''big'' way; the TwistEnding is pretty much the ''only'' thing most people will know when asked about this story, even if they've never read the book or watched the adaptations.
* MainstreamObscurity: Just ask a member of the general public to give you even a vague summary of the plot! As mentioned above, most people ''don't even know'' that the dual identity was originally a TwistEnding, and it is not uncommon to see [[Film/VanHelsing parodies]] [[TheLeagueOfExtraordinaryGentlemen of it]] where Hyde is literally an ogre monster- rather than simply an evil (but not even particularly ugly) man. To be fair, Hyde is described in the book as a misshapen dwarf so ugly he inspires hatred in people without them even understanding why (possibly an uncanny valley effect due to looking somewhat inhuman).
** A lot of people will assume the two girlfriends are part of the book's plot as well; they were introduced in the 1931 film and added to many subsequent versions.
* MisaimedFandom: Many people will use the idea of being a "Jekyll and Hyde" as an excuse for either their own bad behaviour or that of their loved ones: "The real me (Jekyll) would never do such a thing, it was this alien force (Hyde) that took over my body and made me do it." This arguably inverts the moral of Stevenson's story, where Jekyll's refusal to take responsibility for Hyde's actions was a big part of what caused things to go badly.
* UncannyValley: This is how the other characters describe Hyde and recognize that he's not quite right. They always describe him as looking "deformed" somehow, despite having no outwardly noticeable disfigurements. This is subtlety is lost on subsequent adaptations, mostly because it's hard to show on screen, and partly because EvilIsSexy sells better.
* WhatDoYouMeanItWasntMadeOnDrugs: Inverted. Stevenson wrote the first draft of the story in one-sitting during a speed binge.

!! The 1988 video game provides examples of:
* NightmareFuel: The game has two endings. One of them is reached by simply getting to the church as Jekyll before Hyde. It just shows the church and the word "END" appears while the wedding march plays. A second ending, somewhat hidden, is earned by reaching Level 6 as Jekyll and then proceeding to the end as Hyde. Hyde then fights a boss "demon" at the church, and, upon beating it, turns back into Jekyll. Jekyll's able to reach the church unhindered (all the enemies disappear) and an extended cutscene of the wedding plays. "END" appears when the screen fades out after bride and groom kiss. However, after waiting a while, the music will abruptly stop and the sound effect for the bomb is played. When the bomb "explodes", lightning flashes, the word "END" appears reversed, and Mr. Hype appears as a red silhouette with what appears to be a giant cross embedded into his back. Like everything else about the game, the extended ending is unexplained, leaving it ambiguous (for the wrong reasons) as to whether or not it can be considered a "good" or "bad" ending.
** What throws this into NightmareFuel is that Hyde's silhouette in the second ending comes out of nowhere, and given what happens to Dr. Jekyll in the book, it can be implied that Hyde still "lives", or worse, that the demon he killed took over the Hyde personality. The lighter explanation is that the cross represents Jekyll finally "ending" Hyde by getting married. [[http://www.youtube.com/watch?v=PdrFR76Bs6E This video suggests the latter is a good ending]].
* TheProblemWithLicensedGames: It's WebVideo/TheAngryVideoGameNerd's least favourite game. And he plays a ''lot'' of bad ones.