->''"If each, I told myself, could be housed in separate identities, life would be relieved of all that was unbearable..."''
-->-- '''Henry Jekyll'''

Source of the JekyllAndHyde trope, this 1886 book by Creator/RobertLouisStevenson has been much filmed, but practically all the films turn the plot inside out. Note that the original title was ''Strange Case of Dr Jekyll and Mr Hyde'', omitting the "The" for some reason.

The book begins with a mystery. When a girl is brutally attacked late one night, her attacker, calling himself Mr Edward Hyde, buys off the witnesses with a cheque for a small fortune, signed by the eminently respectable Doctor Henry Jekyll.

Jekyll's friend and legal advisor, Gabriel John Utterson, is disturbed when he learns this, since Jekyll has recently made Hyde his heir. While Utterson investigates this, Hyde is witnessed committing a savage murder of a prominent Member of Parliament. Jekyll claims there is nothing to worry about, but Utterson becomes convinced his friend is being blackmailed.

Before Utterson can do anything, Jekyll's butler Poole contacts Utterson to report that a stranger has locked himself in the lab. When they break into the room they find Hyde, having committed suicide by poison, and two letters explaining everything.

Jekyll had been trying to invent a [[AppliedPhlebotinum potion]] which could separate his good and evil sides. When [[ProfessorGuineaPig Jekyll tested it]], he was now transformed into 'Mr Hyde', a manifestation of his evil side with no trace of morality, but his normal personality remained unchanged. In other words, as Dr. Jekyll he was a man with mostly good and ''some'' evil urges, as Mr Hyde he was a man with only evil urges. After some cautious experimenting, Jekyll decided he ''liked'' this side-effect. As Mr Hyde, he could indulge himself in every pleasurable vice, and never be suspected as Hyde looked completely different. However, Hyde eventually committed murder, Jekyll resolved [[TemptingFate never to use the potion again]].

But after a few months, Jekyll began spontaneously changing into Hyde. Only by drinking the potion could he retain his own form, and the potion was running out -- not to mention that ever since the murder, the police had been searching relentlessly for Edward Hyde. When Jekyll made a new batch of the potion, it didn't work; his original chemical samples had been contaminated, and it was the impurities that had made the transformation possible. At the end of his letter, Jekyll writes that he soon will change into Hyde, and thus his life will end.

Naturally, there have been several adaptations and parodies of this book. What makes them particularly interesting is not that each one changes, deletes, or adds certain elements but that they [[RetCanon tend to make the same changes]]. In addition to (or instead of) the above story, here's what you'll usually find in film and stage versions:

* Cutting the TwistEnding: The book is presented as a mystery, with the identity of Hyde as the TwistEnding, but this is completely absent from all films, mainly because [[PopcultureOsmosis the twist is now too famous to surprise anyone]].
* The physical appearance of Hyde: The films typically show Hyde as looking monstrous, contrary to the book's description. Hyde is described as looking repugnant, but not because of any particular physical abnormality. His appearance is rather normal, if a bit dwarfish; it's just that people can somehow sense his great depravity. Adaptations also tend to portray Hyde as more physically formidable than Jekyll, even huge and super-human in some versions, while in the novel Jekyll is a large man and Hyde, representing Jekyll's "less developed" evil urges, is smaller than average. On the other hand, some recent adaptations have [[HotterAndSexier portrayed Hyde as more attractive than Jekyll]] in keeping with the EvilIsSexy trope.
* The nature of the SplitPersonality: Jekyll is usually unaware of Hyde's actions, suffering from [[IdentityAmnesia split personality amnesia]]. This is not in any way suggested by the book, in which Jekyll ''does'' remember everything he did as Hyde, but [[MyGodWhatHaveIDone begins to find his own depravity horrifying]] and tries to dissociate himself from it.
* [[LoveInterest Love Interests]]: Jekyll's good girl fiancée and Hyde's slutty barmaid/prostitute girlfriend. This plot thread, not part of the original story, occurs in almost '''ALL''' adaptations.

Specific adaptations include:
* A highly successful stage play that opened in America not long after the book came out and toured for 20 years. It was this play that introduced the idea of the two love interests.
* Straightforward adaptations in 1919 (with John Barrymore), [[Film/DrJekyllAndMrHyde1931 1931]] (with Creator/FredricMarch and Miriam Hopkins), 1941 (with Creator/SpencerTracy, Creator/IngridBergman and Lana Turner) and 1960 (a Hammer version with Paul Massie). All these adaptations made substantial changes to the main plot - in particular, Jekyll tends to be cast much younger than he is in the novel, and a female love interest is usually added. They also abandon the character of Utterson and his investigation for a story centered on Jekyll and Hyde. Also, the March version is the only one to regularly use the (little-known) correct pronunciation of "Jekyll" (''Jee''-kyll). The 1931 film is probably the best-regarded film version. It offers a rare case of a horror film winning an UsefulNotes/AcademyAward, as March won Best Actor for his portrayal of Jekyll and Hyde.
* ''The Janus Head'', a 1920 silent German film version directed by F.W. Murnau and starring Conrad Veidt. It changes the characters' names to Dr. Warren and Mr. O'Connor. Also has a very young Bela Lugosi as the butler. It is also apparently lost forever, but if the production notes are to be believed, it has the first moving camera in cinema history.
* Stephen Weeks's version, ''I, Monster'' (produced by Creator/AmicusProductions) keeps to the original plot but changes the names of Jekyll and Hyde in an attempt to keep the twist.
* ''Film/TheNuttyProfessor'' (both Creator/JerryLewis' and Creator/EddieMurphy's versions) are comedic takes on the concept, where a nerdy scientist changes into a cool guy.
* The TV sitcom ''Series/FamilyMatters'' has geeky Steve Urkel develop a potion that turns him into the suave, handsome Stephan Urquelle.
* ''The Two Faces of Doctor Jekyll'' puts an interesting twist on the Jekyll/Hyde dichotomy: Jekyll is hirsute, sloppy dressed, mannerless and abrasive, while Hyde is elegant, suave, charming and debonair.
* ''Dr. Heckyl and Mr. Hype,'' a 1980 comedy/horror with Creator/OliverReed, followed the ''Nutty Professor'' formula: the kindy Heckyl is horribly ugly while his violent alter-ego is good-looking.
* The 1971 Film/HammerHorror ''Dr. Jekyll and Sister Hyde'' and the 1995 comedy ''Dr. Jekyll and Ms. Hyde'' both add a GenderBender twist to the story.
* ''Mary Reilly'' tells the story with a romance/horror twist: Hyde was Jekyll's attempt to become young and strong again.
* Frank Wildhorn and Leslie Bricusse adapted it during the '90s into a stage musical, ''Theatre/JekyllAndHyde''.
* ''Series/{{Jekyll}}'', a 2006 modern day TV miniseries involving a descendant of the pair, written by Creator/StevenMoffat. Also notable for an example of using the 'Jee-kyll' pronunciation.
* In ''Comicbook/TheLeagueOfExtraordinaryGentlemen'' and its [[Film/TheLeagueOfExtraordinaryGentlemen film adaptation]], Jekyll and Hyde are made into {{Exp|y}}ies of Bruce Banner and the Comicbook/IncredibleHulk, who were in turn based off Jekyll and Hyde. The pair can communicate - Jekyll sees Hyde in mirrors, and omnipresent in his subconscious. Hyde's powers of perception are not usable by Jekyll except if the former advises the latter. The comic depicts Hyde as a huge, monstrously strong humanoid, which Hyde himself explains - separated into distinct individuals, Jekyll grows weak and frail without Hyde's passion, while Hyde grows in power without Jekyll's morals to limit him.
* ''Film/VanHelsing'' had Hyde as the first monster the titular Van Helsing fights. Hyde is an ape-like monster who battles Van Helsing in the BatmanColdOpen. Hyde turns back into Jekyll on his death, unlike the original story.
* An animated prequel of ''Film/VanHelsing'' fleshes out the story. Apparently the doctor has the hots for Queen Victoria of England. And he harvests essence from young women to make a temporary youth potion for the queen.
* A direct-to-video version starring [[Film/{{Candyman}} To]][[Film/StarTrekVTheFinalFrontier ny To]][[FinalDestination dd]] in 2009. Unlike most adaptations, it tried to remain close to the novel by giving the impression that Jekyll & Hyde were two different people. At least until about two-thirds of the way into the movie.
* An infamous UsefulNotes/NintendoEntertainmentSystem game by Creator/{{Toho}}, which routinely shows up on lists of the worst NES games of all time due to ugly graphics and sadistic FakeDifficulty.
* There's a 70s Blaxploitation flick, ''Dr Black and Mr Hyde'', which cashed in on the Blaxploitation horror craze that was started by ''Blacula''.
* The AnimatedAdaptation by Creator/BurbankFilmsAustralia, which attempts to stick as close to the original novel as possible.
* Creator/{{ITV}}'s series ''Jekyll & Hyde'' follows Robert Jekyll, grandson of the Henry Jekyll from the novel, and is set in the 1930s. It is, according to WordOfGod, a superhero-type show in the vein of X-Men, and as such Hyde is just one of many supernatural creatures targeted by a sinister CreatureHunterOrganization.
* Series three of Showtime's ''Series/PennyDreadful'' introduces us to Doctor Jekyll as a half-Indian, half-British young chemist, [[EveryoneWentToSchoolTogether who went to medical school with Victor Frankenstein]].
* A minor character in ''Literature/WelkinWeasels'' is Professor Speckle Jyde, a mild-mannered gerbil who yearns to be a troublemaker, and so creates a potion that turns him into the obnoxious shrew Dr Lycan Heck.

!!This book provides examples of:

* AllThereIsToKnowAboutTheCryingGame: The work is [[MainstreamObscurity well-known by name]], but all that most people have heard about it is [[JekyllAndHyde the twist ending]]. Many do not even know that the dual identity story was originally a twist at all, and most newer adaptations treat it as a foregone conclusion. Some even make Hyde himself some sort of ugly were-monster rather than just a really evil man, most notably in the infamous NES game released by Bandai.
* AlternateIdentityAmnesia: Neither Jekyll nor Hyde have very clear memories of what the other does.
* AmateurSleuth: This is basically Utterson's role in the original story.
* ApocalypticLog: TheReveal comes in ''two'' of these, one left by Dr. Lanyon, giving an account of how Jekyll revealed his secret to him, and the second a confession by Jekyll himself, written after he could no longer make the formula and realized Hyde would take over completely. Both are read by Utterson and they make up Chapters 9 and 10.
* AppliedPhlebotinum: The means by which Hyde is created. This was a time when chemistry, and especially the workings of the human mind, were still relatively unknown (even more so than today, that is), and therefore could be used in the same way radiation was used as a reason for giant monsters and superpowers in the 1950s.
* BastardBastard: Hyde is not only smaller but younger-looking than Jekyll, and Utterson briefly wonders if he's the by-blow of Jekyll's youthful indiscretions (though the story phrases it far less bluntly):
-->"Poor Harry Jekyll," he thought, "my mind misgives me; he is in deep waters! He was wild when he was young; a long while ago to be sure; but in the law of God, there is no statute of limitations. Ay, it must be that; the ghost of some old sin, the cancer of some concealed disgrace: punishment coming, ''pede claudo'', years after memory has forgotten and self-love condoned the fault."
* BigBad: Edward Hyde, Jekyll's evil given form.
* BitterAlmonds: "The strong smell of kernels that hung in the air"--that is, almond kernels. Hyde has taken cyanide.
* {{Blackmail}}: Near the beginning of the book, Jekyll has changed his will to leave everything to Hyde; the protagonists of the book believe Hyde is blackmailing Jekyll.
* BodyHorror: Though not pushed as far as later writers went with it.
* TheCaseOf: One of the earliest works to use this intriguing title template.
* ChromosomeCasting: The only female characters are several of Hyde's victims mentioned in passing, as well as Hyde's landlady and Jekyll's cook.
* ADarkerMe: This is the appeal of Hyde for Jekyll; he even refers to Hyde as "the darker side of my nature".
--> '''Jekyll''': This, too, was myself. It seemed natural and human.
* DeadManWriting: Jekyll wrote a complete briefing about what happened to him (it's the last chapter of the book), but it mustn't be opened before his [[SplitPersonalityTakeover disappearance]] or death.
* DevilInPlainSight: Everyone can sense that there is something wrong with Hyde, mostly because he is pure evil. They think he might be deformed in some way, but nobody can quite put their finger on how.
* DoesThisRemindYouOfAnything:
** The book is a thinly veiled metaphor for drug addiction. Stevenson was an opium user.
** The description of Sir Danvers' beauty- thought by some to make him sound rather camp- also gets read like this.
* DrivenToSuicide: After Jekyll realizes that Hyde will take all control of him - both of his body and his personality - he restrains himself to his lab until the final transformation. Hyde takes cyanide when Utterson shows up outside the lab and demands to see Jekyll.
* EvilFeelsGood: Only the original version, not the adaptations. This is the very reason Jekyll thinks separating his evil side from his good side is a good idea -- as Hyde, he's free to do anything without restraint from the law -- or, far more importantly, his own conscience. This was a very prescient idea in Victorian England.
* EvilIsNotAToy: Releasing Hyde -- Easy. Getting rid of him -- Not so much.
* EvilMakesYouUgly: In comparison to the middle aged but handsome Jekyll, Hyde is "troglodytic" and "ape-like" in appearance.
* ExtraExtraReadAllAboutIt: "Special edition! Shocking murder of MP!"
* {{GIFT}}: The great appeal of Hyde to Jekyll is that he can't be held responsible for Hyde's crimes.
--> '''Jekyll''': But for me, in my impenetrable mantle, the safely was complete. Think of it--I did not even exist! Let me but escape into my laboratory door, give me but a second or two to mix and swallow the draught...and whatever he had done, Edward Hyde would pass away like the stain of breath upon a mirror; and there in his stead, quietly at home...would be Henry Jekyll.
* GoMadFromTheRevelation: Dr. Lanyon after he sees Hyde transform into Jekyll for the first time.
* GoneHorriblyWrong: The potion was ''supposed'' to completely separate the good and evil sides. Instead, it just separated the evil side, meaning that Jekyll was never 'pure good' to balance out the 'pure evil'. Notably, Jekyll considers this a good thing at first, because it allows him to act out all his repressed evil urges. Doing that [[GoneHorriblyRight works out pretty well]], until the SplitPersonalityTakeover starts kicking in...
* HairTriggerTemper: Some minor annoyance in conversation with Danvers Carew causes Hyde to fly into a rage and beat him to death.
* HaveAGayOldTime:
** Here is how Mr. Enfield explains his reluctance to start asking questions about other people's business:
--> "...the more it looks like Queer Street, the less I ask."
** Then there's how Jekyll describes the duality of man, using an old word for a bundle of sticks:
--> "It was the curse of mankind that these incongruous faggots were thus bound together...."
* HearingVoices: It is highly suggested in the final chapter that Jekyll was able to hear Hyde inside his head, because "(Hyde) was constantly demanding to get out". However, there is no sentence that 100% confirms this.
* {{Hypocrite}}: Jekyll does not take responsibility for the evil actions of Hyde, yet he takes the potion specifically to enjoy performing evil actions as Hyde. Stevenson called this Jekyll's FatalFlaw in a letter to a friend.
* IncrediblyLamePun
--> '''Utterson:''' If he be Mr. Hyde, I shall be Mr. Seek
* InvoluntaryShapeshifter: After months of taking the potion, Jekyll finds that he is turning into Hyde without it.
* JekyllAndHyde: The {{Trope Namer|s}} -- oh, and this is now a byword of someone who is nice one minute, nasty the next.
* KillingYourAlternateSelf: Faced with becoming the monstrous alter-ego Hyde permanently, Jekyll apparently commits suicide. His body is found with a letter ending "I bring the life of that unhappy Henry Jekyll to an end." Perhaps the oldest example of this trope.
* MiraculousMalfunction: An "impurity of salt" is what makes the transformation from Dr. Jekyll into Mr. Hyde possible. This is what finally dooms Jekyll--he doesn't know what the impurity is, and when his salt runs out, he can't replace it.
* MyGodWhatHaveIDone: Jekyll after Hyde kills Danvers Carew. After this, he stops characterizing Hyde as being a part of himself, instead attempting to distance himself from the persona by referring to Hyde as a separate entity attempting to seize control of his body.
* TheNapoleon: Hyde is frequently described as being "short," "small" and even "dwarfish," in contrast to the taller Jekyll. This is explained as being because Jekyll never indulged in his evilness before, so his evil side is "underdeveloped." Hyde is, however, very dangerous.
* NeverMyFault: Even when writing his final letter, Jekyll still insists that, even now, he doesn't consider Hyde's actions ''his'' actions. ([[HypocrisyNod His choice of pronouns says otherwise]].)
* NoPlansNoPrototypeNoBackup: This is an accident on Jekyll's part, as it turns out to be an unknown impurity that makes the stuff work.
* NoPronunciationGuide: It should be "''Jee''-kyll", not "''Jeh''-kyll". Not that ''that's'' ever stopped anybody from pronouncing it "''Jeh''-kyll" for decades.
* NoodleIncident: Stevenson never goes into great detail about most of the things that Hyde does on his nightly escapades before crossing the MoralEventHorizon by murdering Sir Danvers Carew for no reason; the narrative only states that his activities were of an evil and lustful nature. Given the Victorian England setting and what was considered abhorrent for the time, he may have been engaging with prostitutes and drinking heavily in shady taverns, but we can only surmise.
* ObviouslyEvil: Hyde's appearance is banal, yet everyone who looks at him instinctively recognizes his evil.
* ProfessorGuineaPig: The UrExample, beating out ''Literature/TheInvisibleMan'' by a decade.
* PsychoSerum: TropeMaker
* PureIsNotGood: Henry Jekyll, a man with mostly good and some evil urges, thinks that if he could separate his good and bad urges into separate identities, life would be better, because he would be free of morality and could indulge himself on every pleasurable vice without hypocrisy. Then his bad side crosses the MoralEventHorizon and Jekyll’s life is threatened. ''The only thing that kept Jekyll safe was his hypocrisy''. Mirrored with the “impurity of salt”, the impurities had made the potion work. ''Without the contamination of the samples, he cannot make the transformation work''.
* SexIsEvilAndIAmHorny: It is implied that among the aforementioned vices was womanizing. In his confession, the doctor characterizes "a certain impatient gaiety of disposition" as the worst of his vices. At the time, "gay" was used to describe a ''heterosexual'' person who was inordinately lustful.
* ShadowArchetype
* TheSmurfettePrinciple: One of critics' favorite subjects is how no nominal women appear in the original book or even get involved in the plot except as spectators or victims.
* SplitPersonalityTakeover: Likely the UrExample.
* TechnicolorScience: The potion starts out red and then turns purple before settling on green.
* ThisIsYourBrainOnEvil: The addiction metaphors are obvious... and appropriately creepy. This was written at a time when the effects of opium addiction were just coming to light.
* TwistEnding: The "[[ItWasHisSled twist]]" comes at about the 3/4 mark, and then closes out with Jekyll's own posthumous explanation for everything that happened.
* UnstoppableRage: After Hyde goes into a rage and attacks Carew, he exults in the thrill of the evil action and beats the man to death.
* WouldHurtAChild: In his first appearance Hyde literally walks over a little girl he meets on the street.
!!Adaptations with their own pages include:

* ''Film/DrJekyllAndMrHyde1931'' (film)
* ''Theatre/JekyllAndHyde'' (musical)
!!Tropes common to multiple adaptations:
* AdaptedOut / DemotedToExtra: The fate of Mr. Utterson, due to most every adaptation centering on Jekyll from the start rather that Utterson investigating a mystery, as the novel did. In the 1920 film he pops up towards the end as one of Jekyll's friends, in the 1931 film he is an extra, and in the 1941 film he's completely omitted.
* AdaptationalBadass: The part about Hyde being a diminutive man, much smaller than Jekyll, is usually adapted out. Instead, Hyde is usually portrayed as a burly brute of a man, larger than Jekyll.
* AdaptationalHeroism: Most adaptations of the original story completely rewrite Jekyll's motivations for separating good from evil. In the original story, Jekyll wanted to do it so he could evade responsibility and consequences for his actions by separating himself from not just his appearance and name, but his conscience as well, giving him freedom to do whatever he pleased. Most adaptations, possibly to emphasize the good vs. evil dynamic of Jekyll and Hyde, have made Jekyll into a humanitarian saint of science who wanted to separate good from evil to eliminate wrong from the world, and in the case of the musical, cure insanity, particularly his father's tragic case.
* ArtifactTitle: A good number of adaptations preserve the "Strange Case" portion of the original title. Although to the modern audience, it's not much of a mystery anymore since adaptations, unlike the original story, typically show the story from Jekyll's point of view.
* BettyAndVeronica: Many adaptations add contrasting female companionship options that weren't in the book, an innocent girlfriend/fiancee for Jekyll and for Hyde an earthier, more sexually available woman that he brutalizes.
* PragmaticAdaptation: Jekyll wasn't the central character of the original story--the story is told from the POV of Mr. Utterson, Jekyll's old friend and lawyer who investigates the mystery. Most of the original story depicts Hyde's actions as being told about instead of shown. The twist ending was revealed in a letter where everything is again told instead of shown. Most adaptations, instead, focus on depicting Jekyll's dramatic struggle between his two selves and his eventual downfall, since everybody already knew the ending. (Utterson, the main character, is a bit part in the 1931 film and is left out of the 1941 film completely.)
* SuperPoweredEvilSide: In many modern adaptations, such as ''Van Hellsing'' and [= ITV's=] ''Jekyll and Hyde'', Hyde possesses superhuman powers, most commonly inhuman strength.

!!The 1920 movie provides examples of:
* ChekhovsGun: The PoisonRing that Hyde takes from Gina. At the end, Jekyll swallows the poison to stop Hyde from raping Millicent.
* TheFilmOfTheBook: While still using the BettyAndVeronica trope and not being a mystery, this film is somewhat more faithful to the novel than the 1931 and 1941 adaptations. Utterson appears in this version, although his importance is reduced, and Jekyll poisons himself rather than being shot as in 1931 and 1941.
* OpiumDen: Hyde visits one, although he doesn't take any opium.
* PinkElephants: An opium addict in withdrawal starts hallucinating red ants.
* PoisonRing: Gina, the Italian dancer that is the Veronica in this version's BettyAndVeronica pair, has an old ring that has a secret capsule for storing poison (this actually being an old myth about Lucrezia Borgia).
* ShoutOut: Sir George Carew's quote, "The only way to get rid of a temptation is to yield to it", is a direct lift from Creator/OscarWilde and ''Literature/ThePictureOfDorianGray''.

!!The 1941 movie provides examples of:
* GettingCrapPastTheRadar: A pretty startling example for 1941. During another transformation montage, we see Jekyll as a carriage driver whipping his horses. Then the horses transform into Creator/IngridBergman and Lana Turner, and Jekyll continues to whip them.
* GoryDiscretionShot: What Hyde did to Ivy's back is only seen by the other characters. Later, it's implied that he strangles Ivy and beats Beatrix's father to death, but in both cases the victim is kept off-screen.
* NotEvenBotheringWithTheAccent: Tracy, like March before him, doesn't even try for any kind of British accent.
* VisualInnuendo: During one of the hallucinatory montages when Jekyll transforms into Hyde, he has a vision of Ivy the barmaid's head as the cork in a champagne bottle--and the cork pops.