The Strange Case of Doctor Jekyll and Mr. Hyde

""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 Jekyll and Hyde trope, this book by Robert Louis Stevenson 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 adviser, 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 potion which could separate his good and evil sides. When he tested it, he was 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, and as 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, and Jekyll resolved 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.

There have been several film adaptations and parodies of this book, including:
 * Straightforward adaptations in 1919 (with John Barrymore), 1931 (with Fredric March and Miriam Hopkins), 1941 (with Spencer Tracy, Ingrid Bergman 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. Also, the March version is the only one to regularly use the (little-known) correct pronunciation of "Jekyll" (Jee-kyll).
 * The pronunciation is debatable as although the author was Scottish and therefore would probably pronounce it "Jee-kyll" the character himself comes from London and therefore would pronounce it the usual way.
 * 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 Hammer's main rival Amicus) keeps to the original plot but changes the names of Jekyll and Hyde in an attempt to keep the twist.
 * The Nutty Professor (both Jerry Lewis' and Eddie Murphy's versions) are comedic takes on the concept, where a nerdy scientist changes into a cool guy.
 * This variation would later be done on the TV sitcom Family Matters when geeky Steve Urkel developed a potion that could turn 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 Oliver Reed, followed the Nutty Professor formula: the kindly Heckyl is horribly ugly while his violent alter-ego is good-looking.
 * The 1971 Hammer Horror Dr. Jekyll and Sister Hyde and the 1995 comedy Dr. Jekyll and Ms. Hyde both add a Gender Bender 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, Jekyll and Hyde.
 * Jekyll, a 2006 modern day TV miniseries involving a descendant of the pair, written by Steven Moffat. Also notable for an example of using the 'Jee-kyll' pronunciation.
 * In The League of Extraordinary Gentlemen movie, Jekyll and Hyde are made into Expies of Bruce Banner and the Incredible Hulk, 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.
 * Van Helsing had Hyde as the first monster the titular Van Helsing fights. Like the "League of Extraordinary Gentlemen" version, Hyde is an ape-like monster, though in this version no justification is given. Also Hyde turns back into Jekyll on his death, unlike the original story.
 * He turns back into Jekyll because the potion wears off; the fact that he dies moments later is coincidence.
 * A direct-to-video version starring Tony Todd 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.
 * Stan Lee notably subverted the concept in The Mighty Thor in the 1960s with a villain named Mr. Hyde. Unlike the original story, where Henry Jekyll was a generally upstanding and honest man, Lee's version of Jekyll (named Calvin Zabo) is actually a thieving, spiteful bastard who deliberately seeks to unleash his inner monster and willingly embraces his power, using it to indulge his grudges and sadistic urges.
 * An infamous Nintendo Entertainment System game by Toho, which routinely shows up on lists of the worst NES games of all time due to ugly graphics and sadistic Fake Difficulty.

While the book is presented as a mystery, with the identity of Hyde as the Twist Ending, this is absent from the films, mainly because the twist is now too famous to surprise anyone.

The films also typically show Hyde as looking monstrous, contrary to the book's description. Hyde is described as looking repugnant, but not because of any physical abnormality. His appearance is perfectly normal; 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 portrayed Hyde as more attractive than Jekyll in keeping with the Evil Is Sexy trope.

Further, in pretty much every later adaptation, Jekyll is unaware of Hyde's actions, suffering from split personality amnesia. This is not in any way suggested by the book, in which Jekyll does remember everything he did as Hyde, but begins to find his own depravity horrifying and tries to dissociate himself from it.

""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.""
 * All There Is to Know About "The Crying Game": The work is well-known by name, but all that most people have heard about it is 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.
 * Applied Phlebotinum: The means by which Hyde is created. This was a time when science, chemistry (alchemy was still trendy), and especially the workings of the human mind were still considered magic.
 * Bastard Bastard: 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):


 * Actually, this might be a case of Ambiguously Gay. As it comes across more like he believes something odd is happening between Jekyll and Hyde, and he never once mentions a woman during the monologue, simply that Jekyll was "wild in his youth". Not to mention that "pede claudo" was an old term that could mean (among other things) a "homeless homosexual".
 * Body Horror
 * A Darker Me: See Alternative Character Interpretation—a possible subtext of the book is that Hyde is only evil because Jekyll's anonymity lets him get away with it.
 * Dead Man Writing: 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 of his disappearance or death.
 * Devil in Plain Sight: Used in later adaptations. In the original novel Hyde looks like a normal Victorian era 'gentleman', but everyone can sense that there is something wrong with him, mostly because he is pure evil.
 * Driven to Suicide: 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.
 * Evil Feels Good: 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.
 * Also used in the Fredric March version, where its clear Jekyll uses Hyde to indulge his frustrated sexual desires.
 * Evil Is Not a Toy: Releasing Hyde—Easy. Getting rid of him—Not so much.
 * Freudian Excuse: See "alternative character interpretation" above. He's turning evil? Really? Or maybe he just needs an excuse to act on his repressed urges? It doesn't get more Freudian than that, does it. Notably, it predates Freud's development of psychoanalysis by a few years.
 * Go Mad from the Revelation: Dr. Lanyon after he sees Hyde transform into Jekyll for the first time.
 * Gone Horribly Right: The potion that separates good and evil seemed like a good idea, but Jekyll forgot that one little possible side-effect...
 * Hearing Voices: 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; Stevenson described this as Jekyll's Fatal Flaw in a letter to a friend.
 * He attempts to deny this, saying that he puts all of himself into his work and his sinning equally.
 * Incredibly Lame Pun: "If he shall be Mister Hyde, I shall be Mister Seek."
 * This troper's English class rather thought that line was more of a Funny Moments, if only because of the juxtaposition of a popular children's game with the odd-sounding formal 19th century language.
 * Involuntary Shapeshifter
 * Jekyll and Hyde: The Trope Namers—oh, and this is now a byword of someone who is nice one minute, nasty the next. Remember what we said about All There Is to Know About "The Crying Game" and It Was His Sled?
 * Mad Scientist
 * Miraculous Malfunction: An impurity of salt is what makes the transformation from Dr. Jekyll into Mr. Hyde possible.
 * My God, What Have I Done?: Jekyll after Hyde kills Danvers Carew.
 * The Napoleon: Hyde is frequently described as being "small" and "shorter than average". This is explained as being because Jekyll never indulged in his evilness before, so his evil side is "underdeveloped".
 * Never My Fault: Even when writing his final letter, Jekyll still insists that, even now, he doesn't consider Hyde's actions his actions. (His choice of pronouns says otherwise.)
 * No Plans, No Prototype, No Backup: This is an accident on Jekyll's part, as it turns out to be an unknown impurity that makes the stuff work.
 * No Pronunciation Guide: It should be "JEEK-il", not "JECK-il".
 * Obviously Evil: Hyde's appearance.
 * Professor Guinea Pig: The Ur Example, beating out The Invisible Man by a decade.
 * Shadow Archetype
 * The Smurfette Principle: 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. For some reason, you would never know this from most adaptations...
 * Split Personality Takeover
 * Technicolor Science: The potion starts out red and then turns purple before settling on green.
 * This Is Your Brain on Evil: 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.
 * Twist Ending: Hard to believe these days because It Was His Sled.
 * Uncanny Valley: 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, but mostly because it's hard to show on screen.
 * Unstoppable Rage: Hyde has no superego and therefore never restrains his rage.

The 1931 movie provides examples of

 * Academy Award: Frederic March's Best Actor win is one of the very few times the Academy has chosen to honor a horror film. (The clean sweep by The Silence of the Lambs is a more dramatic example.)
 * Hays Code: This film predates it, and has some racy for its day moments (mostly with Ivy).
 * The Oner: The movie begins with a three-minute continuous shot which moves between two interiors across a large set—both technically and aesthetically daring for the time. Even more impressively, this shot is from Jekyll's point of view. At one point the camera-as-Jekyll even looks in a mirror; the production had the actor standing on the other side of a glassless frame, with a duplicated section of room-scenery behind him.

The 1941 movie provides examples of

 * Does This Remind You of Anything?: 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.
 * Getting Crap Past the Radar: 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 Ingrid Bergman and Lana Turner, and Jekyll continues to whip them.
 * Not Even Bothering with the Accent: Tracy.