The literary canon of Sherlock Holmes consists of the fifty-six short stories and four novels written by Arthur Conan Doyle. See Franchise.Sherlock Holmes for more information about the character and the various adaptations of Sherlock Holmes.For tropes found in the novels, visit their work pages. For tropes found in the short stories and general tropes regarding the character, see below.
Contains 12 stories published in The Strand between July 1891 and December 1892 with original illustrations by Sidney Paget.
"A Scandal in Bohemia"
"The Adventure of the Red-Headed League"
"A Case of Identity"
"The Boscombe Valley Mystery"
"The Five Orange Pips"
"The Man with the Twisted Lip"
"The Adventure of the Blue Carbuncle"
"The Adventure of the Speckled Band"
"The Adventure of the Engineer's Thumb"
"The Adventure of the Noble Bachelor"
"The Adventure of the Beryl Coronet"
"The Adventure of the Copper Beeches"
The Memoirs of Sherlock Holmes
Contains 12 stories published in The Strand as further episodes of the Adventures between December 1892 and November 1893 with original illustrations by Sidney Paget.
"The Adventure of the Cardboard Box" (this story is included as part of His Last Bow in American editions of the canon)
"The Adventure of the Yellow Face"
"The Adventure of the Stockbroker's Clerk"
"The Adventure of the Gloria Scott" (Holmes's first case, described to Watson)
"The Adventure of the Musgrave Ritual" (another early case, told by Holmes to Watson)
"The Adventure of the Reigate Squire"
"The Adventure of the Crooked Man"
"The Adventure of the Resident Patient"
"The Adventure of the Greek Interpreter" (Mycroft appears for the first time)
"The Adventure of the Naval Treaty"
"The Final Problem" (Watson reports the death of Holmes; Professor Moriarty is introduced)
The Return of Sherlock Holmes
Contains 13 stories published in The Strand between October 1903 and January 1905 with original illustrations by Sidney Paget.
"The Adventure of the Empty House" (the return of Holmes)
"The Adventure of the Norwood Builder"
"The Adventure of the Dancing Men"
"The Adventure of the Solitary Cyclist"
"The Adventure of the Priory School"
"The Adventure of Black Peter"
"The Adventure of Charles Augustus Milverton"
"The Adventure of the Six Napoleons"
"The Adventure of the Three Students"
"The Adventure of the Golden Pince-Nez"
"The Adventure of the Missing Three-Quarter"
"The Adventure of the Abbey Grange"
"The Adventure of the Second Stain"
His Last Bow
Contains seven stories published 1908–1913, 1917.
"The Adventure of Wisteria Lodge" (originally published simply as "A Reminiscence of Mr Sherlock Holmes", this story is made up of two parts given separate titles: "The Singular Experience of Mr. John Scott Eccles" and "The Tiger of San Pedro")
"The Adventure of the Red Circle"
"The Adventure of the Bruce-Partington Plans" (Mycroft appears)
"The Adventure of the Dying Detective"
"The Disappearance of Lady Frances Carfax"
"The Adventure of the Devil's Foot"
" His Last Bow"
The Case-Book of Sherlock Holmes
Contains 12 stories published 1921–1927.
"The Adventure of the Mazarin Stone"
"The Problem of Thor Bridge"
"The Adventure of the Creeping Man"
"The Adventure of the Sussex Vampire"
"The Adventure of the Three Garridebs"
"The Adventure of the Illustrious Client"
"The Adventure of the Three Gables"
"The Adventure of the Blanched Soldier" (narrated by Holmes; Watson does not appear)
"The Adventure of the Lion's Mane" (narrated by Holmes; Watson does not appear)
In the story "Silver Blaze", Sherlock Holmes points out the vital non-clue of a dog failing to react to a mysterious visitor... when a guard dog doesn't bark at an intruder it generally means it's someone he doesn't think is an intruder at all. The scene where Holmes points this out serves as the page quote for the trope.
The absence of certain valuable deeds is a vital clue in "The Adventure of the Norwood Builder."
Addiction Powered: Subverted. Sherlock uses cocaine to stimulate his mind only when he has no sufficiently interesting cases to work on. The challenge of solving a mystery is intellectual stimulation enough that he doesn't need drugs while he's on the job.
Affably Evil: Professor Moriarty, who is gentlemanly enough to let Sherlock write a farewell note to Watson before their fight in "The Final Problem".
"The Adventure of the Lion's Mane" is a gift to zoologists: the murderer is a jellyfish, and the injuries of the dead man plus the title leave no room for doubt.
Animal Assassin: "The Adventure of the Speckled Band." The titular band turns out to be a deadly swamp adder. Also, as the name indicates, "The Adventure of the Lion's Mane" although the title could also be misleading as to the type of animal.
"Lion's Mane" also subverts it in that the animal was not aggressive, and its killings were purely accidental.
Animal Motifs: Lestrade is often described as having bulldog or weasel-like features, usually depending on whether he thinks he's beaten Holmes to the punch.
Arc Words: "The Second Stain" was mentioned several times before its publication.
Aromanticism: Holmes is considered the archetypal aromantic character; as mentioned by Watson in "A Scandal in Bohemia", the famous detective "as a lover...would have placed himself in a false position. He never spoke of the softer passions, save with a gibe and a sneer."
The title character of "Charles Augustus Milverton", who is so unsympathetic that Holmes and Watson allow his killer to get away; also seen in "Black Peter" with a victim who was abusive towards his family and an all around nasty piece of work. The rest of the stories provide plenty more examples. This shows up in "The Boscombe Valley Mystery", "The Cardboard Box", "The Crooked Man", "The Resident Patient", and "The Abbey Grange". In "The Abbey Grange" Holmes and Watson convene a kangaroo court essentially to find the murderer not guilty by reason of this trope.
Subverted/Exaggerated in "The Norwood Builder". The asshole in this story urned out not be a victim at all, but had merely faked his own death and framed an innocent guy for his murder in order to get revenge on the guys mother.
Awesome by Analysis: Holmes lives, breathes and sleeps this trope. Watson has a few examples too.
The Bad Guy Wins: In "A Case of Identity", this happens because of Holmes' sexism. He thinks it's better not to tell his client that her disappeared fiancé was actually her step-father in disguise, because (according to Holmes) "there is danger for him who taketh the tiger cub, and danger also for whoso snatches a delusion from a woman". Holmes even agrees with the culprit that—loathsome though Holmes personally finds him—nothing he's done is legally actionable, despite the fact that breach of promise was a serious thing and she would certainly have won a civil suit against him.
Badass Bookworm: Holmes is not only a brilliant detective, but also an innovative forensic scientist, good violinist, and a formidable martial artist who is strong enough to bend an iron poker with his bare hands — and unbend it again afterwards, the harder task. In "The Adventure of the Beryl Coronet", he actually mentions that he has exceptional strength in his fingers.
Banana Republic: A character in "Wisteria Lodge" turns out to be the escaped dictator of a Central American republic named "San Pedro".
Batman Gambit: Holmes continually employs these on criminals and clients alike to get what he needs. He's even done it to Watson, counting on the good doctor's sincerity and guileless nature to lure a murderer into a trap in "The Adventure of the Dying Detective". However, since Batman is partly based on Sherlock Holmes, this trope isn't really surprising.
Berserk Button: Don't compare Holmes to any other detective, even a fictional one. And more heartwarmingly, don't even attempt to do any harm to Watson in front of Holmes. Holmes also appears to really, really despise blackmailers; most of the Asshole Victim characters whose murderers he refused to expose unless he needed to save an innocent were blackmailers, the remainder mostly being abusive drunks.
Big "WHAT?!": Also a case of Not So Stoic. In "The Man With the Twisted Lip," Holmes has concluded that a young man has most certainly been killed, and arrives to deliver the bad news to his widow, in his most businesslike and sympathetic fashion. Then he learns that she just received a letter from him. His whole reaction is justified (and priceless).
Sherlock Holmes sprang out of his chair as if he had been galvanized. "What!" he roared.
Bewildering Punishment: Watson thinks one man guilty because he does not profess this at being arrested; Holmes points out that he must have realized that the evidence was against him, and his behavior before the murder had been unfilial.
Bittersweet Ending: Quite a few, including The Sign of the Four and "A Scandal in Bohemia".
Black Comedy: "The Adventure of the Three Garridebs", as noted by Watson himself in the introduction.
Blackmail: Charles Augustus Milverton's fortune was made by purchasing documents, always making sure they were genuine, that jeopardized well-to-do people's reputations and then he squeezed them for every penny he could. If they aren't rich enough to make the payment, he made an example of them to other victims.
Also the alleged reason for the King of Bohemia wanting the photograph of himself and Irene Adler: he told Holmes that she would blackmail him with it. Then, in a Twist Ending, we find out that it was rather the other way around.
Blindfolded Trip: In both "The Adventure of the Engineer's Thumb" and "The Greek Interpreter", Holmes' client was bundled into a carriage that they could not see out of and driven to an unknown destination.
Brain Fever: Used in several Sherlock Holmes stories, including "The Copper Beeches" in which a girl's stepfather pesters her about her inheritance until she gets brain-fever; "The Adventure of the Naval Treaty" in which a man is ill for nine weeks after a treaty is stolen from under his nose; and "The Crooked Man", where the dead man's wife is conveniently rendered insensible after witnessing her husband's sudden death.
Breakout Character: Mycroft Holmes and Irene Adler come up more times in adaptations than they ever do in the actual stories: Mycroft only appears in three ("The Adventure of the Greek Interpreter", "The Final Problem" and "The Adventure of the Bruce-Partington Plans") whereas Irene only appears in "A Scandal in Bohemia" and is referenced indirectly in a Continuity Nod in "The Five Orange Pips".
Brilliant but Lazy: Mycroft is not only an Aloof Big Brother to Sherlock, he's an even better detective. Subverted in that, while Mycroft is physically lazy, he's actually an extremely hard-working civil servant whose encyclopedic knowledge frequently decides British national policy. Mycroft could easily have been a detective himself, but as he explains in "The Adventure of the Bruce-Partington Plans" he loathes the idea of doing the legwork needed to actually gather the facts he'd need to make his deductions. Sherlock himself indulges in long periods of lethargy and substance abuse when there's no case to be solved.
Some qualification: Mycroft is better at observation and reasoning, but stinks as a detective. His manner of handling the Greek Interpreter case tips off the bad guys big time, who then come back and try to torture the client to death. The point of the story seemed to be that figuring out someone's profession by their left pinky is a cute trick, but it does not a detective make.
This might also tie in Sherlock's refusal to learn anything he deems unimportant to his work, like the Earth turning around the Sun or cultural history not related to crime. Meanwhile Mycroft needs to exactly know these little things for his line of work.
Holmes himself may sometimes qualify as this, although his "periods of lethargy" as described by Watson often come closer to full-on manic depression than simple laziness.
Bunny-Ears Lawyer: Holmes is a fairly messed up genius and in early stories was Book Dumb in an odd way - knowing minute details about criminal history and the topics of his monographs but barely knowing how to read a map and uninformed about a variety of other topics. He actually has a logical (even if said logic does hail from the moon) explanation for this - he considers the mind to be like an attic, possessed of a limited amount of space and therefore useless if you throw just any old shit in there. So interesting-but-functionally-useless facts like "the Earth revolves around the sun" have no place in the mind of a consulting detective, but some of the more eclectic applications of chemistry with little practical day-to-day use may well occupy the forefront of his mind for weeks at a time if he thinks it'll solve a case.
Bus Crash: Mary Watson's death is only hinted at, by Watson's oblique reference in "The Empty House" to "my own sad bereavement", and Holmes' advice that "Work is the best antidote to sorrow, my dear Watson."
Busman's Holiday: "The Adventure of the Reigate Squire" and "The Adventure of the Devil's Foot".
Call to Apiculture: Holmes retires to keep bees on the Sussex Downs. In "The Lion's Mane" he writes of "the soothing life of Nature for which [he] had so often yearned", a rather hypocritical statement given Holmes used to describe the countryside as the birthplace of the most horrible crimes.
Canon Discontinuity: A minor example. Doyle never seemed to be sure whether Watson's war wound was in his shoulder or in his leg.
The Casanova: Baron Gruner, the villain of "The Illustrious Client" is described as “extraordinarily handsome, with a most fascinating manner. a gentle voice and that air of romance and mystery which means so much to a woman. He is said to have the whole sex at his mercy and to have made ample use of the fact.”
Cat Scare: A cat scares the crap out of Watson as he and Holmes are sneaking through the house of "Charles Augustus Milverton".
Catch Phrase: "It is simplicity itself." and "You know my methods."
Clothes Make the Legend: Even if the cape and hat were not really in the stories, it's hard to imagine Holmes without them. Oddly, in Der Mann der Sherlock Holmes war one character is assumed by everybody to be Holmes because he smokes a pipe, he wears a flat tweed cap, and his companion carries a violin case.
Clueless Mystery: The series predates the fair play convention. As such, you will see that some clues are not announced to the reader at all (e.g. typewriter forensics), or you only receive the act of observation rather than the result of the clue (e.g. tapping something with a stick, but not told the result or what it means). Lampshaded by Holmes in "The Crooked Man".
Holmes: “The same may be said, my dear fellow, for the effect of some of these little sketches of yours, which is entirely meretricious, depending as it does upon your retaining in your own hands some factors in the problem which are never imparted to the reader.”
Combat Medic: Watson literally was this before the start of the series; he encounters home after being invalided home from a tour as an army doctor in Afghanistan. He subsequently acts as both doctor and combat support for Holmes.
Combat Pragmatist: An interesting case: Holmes isn't above breaking the law for a good cause, but still averts this trope - the rules of boxing are sacred. Only on one occasion, when dealing with one really nasty scoundrel, does he take out a riding crop and threaten to give him a good thrashing 'round the ears. On the other hand, Watson, who only breaks society's rules in extreme scenarios (which, living with Holmes, has made them not that rare) will just grab a chair or a fire poker and threaten, with complete intent to use it on his opponent.
Milverton would also qualify, as he carries a gun around to every negotiation to avoid any physical confrontation.
Moriarty is the king of unfair. He doesn't do anything himself, instead dispatching an army of professional killers to pick off his victims in the most sudden, unexpected, and brutal ways. Typically they don't even see it coming. Until, of course, in the final scenes of "The Final Problem" when he's lost everything. He just lunges at Holmes - no weapon, no nothing - with the sole intention of sending Holmes, and probably himself as well, over the Falls.
Compromising Memoirs: A note at the start of one of short stories indicates that there are plenty of people who do NOT want Watson to write these stories. Many others live short lives after Holmes helps them. Conveniently letting Watson tell his tales with impunity.
Counterfeit Cash: The bad guys in "The Adventure of the Engineer's Thumb" are doing this. The engineer in question is asked to examine their metal press.
Cramming the Coffin: In In "The Disappearance of Lady Frances Carfax", the villains are too squeamish to commit murder outright, so they chloroform Lady Frances and hide her in the coffin containing the body of her old nurse, which is due to buried the next day.
Curb-Stomp Battle: In "The Adventure of the Solitary Cyclist", the local bully makes the mistake of picking a fight with Holmes while he is gathering information at the pub. Holmes ignores him until the man backhands him. It doesn't end well for the bully.
Holmes: I emerged as you see me. Mr. Woodley went home in a cart.
Curtain Camouflage: In the adventure "Charles Augustus Milverton", Holmes and Watson break into a blackmailer's house and duck under a curtain when they hear Charles coming in.
Dangerously Genre Savvy: Holmes himself is a rare heroic example. Moriarty and his right hand man Col. Moran also seem to be the only Sherlock Holmes villains smart enough to try to attack him in Baker Street. It would have probably worked on anyone else, but they were messing with the master.
Baron Gruner in "The Adventure of the Illustrious Client" almost manages where Moriarty failed. But then, Holmes himself says he is an enemy of Moriarty's potential and danger.
Deadly Gas: The murder weapon in "The Adventure of the Devil's Foot".
Deadpan Snarker: In every single incarnation, this has been Holmes' trademark. While there is an element of arrogance or annoyance on his part, that's just how he honestly acts.
Descending Ceiling: In "The Adventure of the Engineer's Thumb", said engineer runs afoul of some counterfeiters, and winds up getting trapped inside of their metal press.
Dirty Coward: The true criminal in "The Adventure of the Blue Carbuncle" is scared enough of the consequences of his theft that when an innocent man is accused of the crime he's willing to let the man go to prison. Holmes later exploits this by letting the man go, noting that the case against the innocent man will collapse now that the carbuncle has been found and the true thief is too frightened to ever commit a crime again.
The Dog Bites Back: The killer in "Silver Blaze" turns out to be the horse, spooking when he saw light being lit for an operation intended to lame him slightly.
Charles Augustus Milverton was murdered by the last person he ruined.
Don't You Dare Pity Me!: In "The Crooked Man", a tortured and crippled soldier avoids his old love for fear of her pity.
Downer Ending: Quite a few of these, including "Five Orange Pips", "The Final Problem", "Dancing Men" and The Valley of Fear. The ultimate example has to be "Cardboard Box", in which every single player in the crime is a victim of another player's gainless vindictiveness; Holmes remarks that it's almost enough to make one lose his faith in God.
The Dragon: Colonel Sebastian Moran to Moriarty, as well as most of his associates.
Dying Clue: In "The Adventure of the Speckled Band", the last words of a woman who died under mysterious circumstances (an apparently nonsensical rant about the titular speckled band) is the first clue revealed in that case.
Faux Affably Evil: Baron Gruner of "The Illustrious Client", whose manner is described as "most affable....a superficial suggestion of afternoon tea with all the cruelty of the grave behind it." Holmes clarifies that Gruner's affability is that of "a purring cat who thinks he sees prospective mice."
Females Are More Innocent: This could be the Trope Codifier, as Sherlock Holmes never brought any woman to justice. He would always either allow them to escape or make sure no charges were filed against them. (Though in one case, letting a female culprit escape meant leaving her to the mercies of her dime-store sociopath of a boyfriend.) This courtesy was sometimes extended to men, if they were sufficiently Justified Criminals (or if they had a female accomplice).
Femme Fatale: The King of Bohemia tries to give the impression that Irene Adler is one, helped along by her profession as an opera singer in a time when "actress" was frequently synonymous with "prostitute," and Watson refers to her as "of dubious and questionable memory." However, she has none of the usual earmarks of the trope, particularly not regarding using sexuality to manipulate men.
Finger in the Mail: "The Adventure of the Cardboard Box" has a pair of ears placed in a box but delivered to the wrong person.
Flanderization: Inverted in the sense that the official police detectives were often portrayed as inept bunglers in the early stories, but later cases recognized their own merits and otherwise had them contribute to the case in their own ways. Sadly, many adaptations reverse this process, especially on poor Lestrade.
Follow the Leader: Many later detective characters — Hercule Poirot, Nero Wolfe, Inspector Morse, etc. — were influenced by Holmes in one way or another. Of course, Holmes himself was inspired in no small measure by Poe's Dupin. This is even lampshaded by Watson in the first novel, although Holmes dismisses the resemblance with characteristic smugness. There's also a possible Shout-Out in the new movie, where Watson's fiancée mentions that she likes detective novels and lists Poe as one such author.
Forgets to Eat: Holmes occasionally gets so wrapped up in a case that he doesn't bother to stop for food, and in one, he deliberately starves himself for several days in order for a plan to work properly, leading to his occasionally being described as lean.
Formerly Fit: In "The Adventure of the Sussex Vampire", Holmes's client Robert Ferguson. According to Ferguson, Watson himself also qualifies.
Framing Device: Holmes doing his thing is sometimes this to what basically amounts to a Watson-written drama/romance.
Mycroft Holmes is the other extreme to his brother, being very fat with hands like flippers.
Generic Doomsday Villain: Professor James Moriarty was pretty much created solely to kill off Holmes in "The Final Problem."
Genius Bruiser: Holmes, while being a practiced marksman, swordsman and fist-fighter (but also a few other combat sports, such as Singlestick), also does not lack good old brute strength either. On one occasion, a client's relative threatens Holmes and Watson to back off an assignment. To intimidate them, he grabs an iron poker from beside the fireplace, and bends it with his bare hands. After he left, Holmes takes the same poker and bends it back into shape!
Genius Slob: Holmes could very well be the Trope Codifier. While always personally well-kept, Holmes's concept of organisation amounted to keeping his tobacco in the toe of his Persian slipper, his cigars in the coal-scuttle, and his unanswered letters jack-knifed to the mantelpiece, all the while conducting foul-smelling chemical experiments in his study, and even using his walls for target practice.
Genre Popularizer: Other detectives had come before, but Holmes is arguably responsible for popularizing the detective story in its modern, standalone form.
Giggling Villain: The bad guy that has kidnapped and tortured a victim in "The Greek Interpreter" has an unsettling giggling laugh.
Gone Horribly Right: Holmes's experiment with the powder in "The Adventure of the Devil's Foot". It nearly causes both him and Watson to die in the same manner as the victims in that case.
Good Hair, Evil Hair: A rather vividly described evil pencil mustache belonging to Baron Gruner, the villain of "The Illustrious Client".
Holmes: The Baron has little waxed tips of hair under his nose, like the short antennae of an insect.
The client from "A Scandal In Bohemia" dresses very ostentatiously.
In general, Holmes' meticulous observation of clues in people's clothing gave Conan Doyle justified grounds to describe their clothes in detail.
Good Is Not Nice: Holmes isn't a bad guy, but boy he can be an ass. Made particularly clear in most adaptations.
Good Old Fisticuffs: "The Adventure of Black Peter", "The Adventure of the Solitary Cyclist", "The Adventure of the Naval Treaty", and "The Final Problem".
GPS Evidence: Hey, Holmes wrote that monograph on the many types of tobacco ash for a reason. He put that special sort of attention to detail to use, too; he could tell exactly where mud on someone's shoes came from, and used the info.
Had to Come to Prison to Be a Crook: Mentioned in "The Blue Carbuncle", when Sherlock decides to release the man who stole the title gem: "This fellow will not go wrong again; he is too terribly frightened. Send him to jail now, and you make him a jail-bird for life."
Watson ejaculates in a couple of the books. Back then it just meant to interject a comment into a conversation.
Watson's friend Percy ejaculates every third paragraph in The Summation of "The Adventure of the Naval Treaty".
In "The Second Stain", Lestrade warns one of his officers that he would find himself "in Queer Street." This meant he would be in financial trouble back when it was written, but those unfamiliar with hundred year old British euphemisms might take that comment in a whole different direction.
"The Adventure of Shoscombe Old Place" does one better. Watson describes a suspect thusly: "a boxer, an athlete, a plunger on the turf, a lover of fair ladies, and, by all account, so far down Queer Street that he may never find his way back again.” For what it's worth, a "plunger on the turf" was a reckless gambler who preferred to bet on the horses.
"Very sorry to knock you up, Watson," said he, "but it's the common lot this morning. Mrs. Hudson has been knocked up, she retorted upon me, and I on you." - "The Speckled Band"
"She pulled a little handkerchief out of her muff" - "A Case Of Identity"
"Thank you," said my patient. "but I have felt another man since the doctor bandaged me." - "The Adventure of the Engineer's Thumb". (Of course, he means he feels like another man.)
Higher Understanding Through Drugs: Sherlock Holmes uses cocaine (legal in Victorian London) when he doesn't have a case, because otherwise his mind will burn out like a powerful engine running without a load. Played straight with tobacco: he famously calls one case "quite a three-pipe problem" and stays up all night smoking to solve it.
High Heel-Face Turn: In "The Adventure of the Engineer's Thumb" there is a female character involved with the villain who ends up helping the heroes.
In "The Adventure of the Speckled Band", Dr. Grimesby Roylott is bitten by the poisonous snake he intended to use to murder his stepdaughter Helen. Holmes plays an indirect role in Dr. Roylott's death by attacking the snake with his cane and driving it back through the vent, but notes that he's unlikely to feel much remorse over it.
In "The Adventure of the Copper Beeches", when Jephro Rucastle is maimed by the starved mastiff he releases to kill his imprisoned daughter. Particularly appropriate, as he was the one who ordered the dog starved and imprisoned the girl.
In "Silver Blaze", the killer is revealed at the end to be the titular horse, whom the victim intended to make lame after betting against it.
In "The Five Orange Pips", Holmes know that the bad guys have killed John Openshaw's uncle and father, and that Openshaw is their next target. But he still tells Openshaw to go back home, unescorted. Unsurprisingly, the bad guys meet him on the way home and kill him. Holmes must've been carrying the Idiot Ball that day, because there is only one other short story besides this where a person who has sought his help gets killed.
His experiment with the powder in "The Adventure of the Devil's Foot", which quickly becomes a case of Gone Horribly Right. After Watson barely escapes with Holmes in tow, Holmes even lampshades it:
"Upon my word, Watson! I owe you both my thanks and an apology. It was an unjustifiable experiment even for one’s self, and doubly so for a friend. I am really very sorry. [...] It would be superfluous to drive us mad, my dear Watson. A candid observer would certainly declare that we were so already before we embarked upon so wild an experiment."
Impaled with Extreme Prejudice: In "Black Peter", the victim, an old sea captain, is harpooned through the chest with such force that he is pinned against the wall.
Inner Monologue Conversation: Holmes does the Dupin version (deducing someone's inner monologue through observing their body language) once just to prove that he's as good as Dupin, though he describes it as "showy and superficial".
Insufferable Genius: While rarely outwardly rude, Holmes wasn't exactly big on humility. He even says at one point: "I cannot agree with those who rank modesty among the virtues. To the logician all things should be seen exactly as they are, and to underestimate one's self is as much a departure from truth as to exaggerate one's own powers." (from "The Greek Interpreter")
Inter-Class Romance: "A Scandal in Bohemia" has the "rich guy, common girl" romance with the Prince of Bohemia and Miss Irene Adler. Used to show how superior the resourceful and clever Miss Adler is to her 'superior':
Holmes states that his amazing deductive skills and genius is hereditary, he and his brother both possessing them. He theorized it might have been because they were descended from the famous Vernet line of French painters. Interestingly, Vernet really did have a sister, who did have a few children, one of which would've had to have been a Holmes parent, legitimately or otherwise.
Holmes also believes that Moriarty turned out evil because of "hereditary tendencies of the darkest kind" magnified by his incredible natural genius.
Invincible Hero: Averted, surprisingly. Holmes didn't always win. In "The Five Orange Pips", Holmes freely confesses that he has been beaten four times; three times by men, and once by a woman (which is a Continuity Nod to "A Scandal In Bohemia"). And this was still early in his career. Presumably, those are just the ones where he knew who outsmarted him. In the "Problem of Thor Bridge", Watson mentions his records contain many utter failures. "The Yellow Face" is a whole case about how Holmes nearly screwed the pooch. He ends the case by asking Watson to remind him of this case if it ever seems like he's phoning it in again.
"Watson", said he, "if it should ever strike you that I am getting a little over-confident in my powers, or giving less pains to a case than it deserves, kindly whisper 'Norbury' in my ear, and I shall be infinitely obliged to you."
Jerk with a Heart of Gold: He keeps it well hidden behind a cold, logical exterior, but Holmes isn't entirely without a heart; it usually expresses itself through his friendship with Watson. "The Adventure of the Three Garridebs" presents a particularly striking example.
Karmic Death: Many throughout the stories, but notably the murder of the blackmailer Charles Augustus Milverton. Both Holmes and Watson saw it happen and decided to protect the murderer, who was one of Milverton's victims.
The Klan: The bad guys in "The Five Orange Pips." Controversially, Holmes expresses revulsion at them at a time when they were still publicly seen as a respectable organisation.
Let Off by the Detective: Holmes sometime does this, reasoning that his job is simply to find a solution to a crime. Since he's not technically a member of the police or the courts, he doesn't feel obliged to turn someone over if he thinks their motive was noble.
Locked Room Mystery: "The Speckled Band", in which the victim is killed while locked inside her room.
London Town: 221B Baker Street did not exist at the time (the house numbers only went up to 100 there). Later 221 would be assigned to the Abbey National Building Society (who had to hire a full-time clerk specifically to deal with Sherlock-related fanmail), which has now vacated that office. 221B is allocated to the museum, located between 237 and 241 Baker Street.
Love Martyr: Watson to Holmes, essentially. For every Friendship Moment, there are many more instances of Holmes deliberately making him feel like an idiot or asking him for a favor and then criticizing the way he does it, but Watson is eternally loyal and says that a single sign of affection from Holmes is worth all the grief he puts up with.
The Mafia: Older than Television, at least as far as fiction goes, since the Mafia are the bad guys in "The Six Napoleons". Doyle describes the Mafia as "a secret political society, enforcing its decrees by murder."
Mandatory Unretirement: In "His Last Bow", Holmes, who had retired to the country to raise bees, is revealed to have come out of retirement at the behest of the Prime Minister to catch a German spy. (Doyle wrote one more short story collection later, but in universe, "His Last Bow", set in 1914, is the last Sherlock Holmes story.)
Maybe Magic, Maybe Mundane: ...or maybe just karma. Either way, the murderers of "The Five Orange Pips" meet a sudden end, shortly after Holmes vows revenge.
Master of Disguise: Holmes often disguised himself for his investigations, and in most instances not even Watson recognized him. Notably, Watson can't see through Holmes's disguise when he first returns to London after pretending to be dead. Watson faints when Holmes takes off his disguise.
Irene Adler's claim to fame, canonically, is that she actually noticed Holmes' ploy, saw through his disguise, deduced who he was - and then, just to be sure, disguised herself as a man, sped to his address in time to watch him laughing his way up the steps into 221B Baker Street, still in the disguise he'd just used on her. She then walks past, wishing him good night and using his name. Holmes himself, still drunk on how smart he is, fails to realize he's in disguise and a stranger on the street just called him by name. A fandom was born.
Note that Holmes' ability to see through other people's' disguises wasn't always consistent with his usual perceptiveness. Many fans choose to believe that he did see through disguises, every time: he just didn't let on unless it suited his plans to do so.
Moon Logic Puzzle: While readers may be alerted that some piece of evidence is important, the nature of the evidence might not be known until near the end of the story. Of course, this could be dismissed as an Unreliable Narrator who tells the story from their point of view rather than getting the information from Holmes.
My Greatest Failure: "The Yellow Face", in which Holmes forms a plausible theory for the solution that turns out to be utterly wrong.
Mysterious Past: Sherlock Holmes himself. Watson often wondered what set of circumstances could've produced Holmes, and Holmes never gave away anything about his history, larger family (except his brother), or education. We only know he's descended from French artists and British country squires, he went to University for two years, and has a brother, which doesn't even begin to explain all his weirdness. Then again, we actually learn even less about Watson - but then again, Holmes has way more strangeness to account for. Explaining Holmes' mysterious past is a common topic in pastiche and fanfiction.
Nice Hat: Contrary to what now is popular belief, Holmes did wear a deerstalker. But never in the city, always in the country. In the city he sometimes wore a top hat, when not undercover of course. This is according to the original Sydney Paget illustrations, that Sir Arthur Conan Doyle approved himself (and he usually requested Paget as his artist), so it's canon, or at least more canon that interior illustrations tend to be.
Nice Job Fixing It, Villain: In the "Red-Headed League", if John Clay has kept the League running for two more weeks, Jabez Wilson would not have gotten suspicious and gone to Holmes, who in turn would not have able to foil his heist.
No Celebrities Were Harmed: Charles Augustus Milverton is based off of a real life (alleged) blackmailer, Charles Augustus Howell.
"The Reigate Squire", where thieves broke in a rich landowner's home and made off with "an odd volume of Pope's Homer, two plated candlesticks, an ivory letter-weight, a small oak barometer, and a ball of twine".
"The Adventure of the Veiled Lodger" opens with a veiled threat to whomever has been attempting to steal Watson's papers that if the attempts continue, he'll publicise the full details regarding "the politician, the lighthouse and the trained cormorant".
Occasional references are made to Noodle Clues from unpublished cases, such as one Holmes solved by winding a dead man's watch, or another solution based on how far some parsley had sunken into the butter on a hot day.
Gilbert Adair, in the somewhat bizarre finale 'And then there was no one' to his trilogy of murder mystery pastiches, actually gives the full story of 'The Giant Rat of Sumatra'. And it's surprisingly Doyle-like.
No Pronunciation Guide: Holmes' name is supposed to be pronounced with an audible l, not "homes" as it often is. Whether this is followed or not seems to be a dialectal thing, related to how people pronounce similar words like "balmy".
Also, adaptations vary in how they pronounce Lestrade's name, it can rhyme with 'hard' or with 'aid'.
Not So Stoic: Holmes in "The Three Garridebs", after Watson gets hurt.
(Holmes speaking) "You're not hurt, Watson? For God's sake, say that you are not hurt!" It was worth a wound—it was worth many wounds—to know the depth of loyalty and love which lay behind that cold mask. The clear, hard eyes were dimmed for a moment, and the firm lips were shaking. For the one and only time I caught a glimpse of a great heart as well as of a great brain. All my years of humble but single-minded service culminated in that moment of revelation.
There are a few minor examples of Holmes' unshockable demeanour being cracked by a sufficiently out-of-the-blue revelation: "The Adventure if the Noble Bachelor," when Watson reads that the bride went missing; "The Second Stain," when Watson tells him he won't be able to talk to one of his suspects, because he's dead; and "The Man with the Twisted Lip," when the wife of a man thought to be dead announces she's had a letter from him.
Holmes's initial exclamation after Watson saves his life after the near-disastrous experiment with the powder in "The Adventure of the Devil's Foot" is specifically noted as a case of this by Watson.
Oddball in the Series: In his later years Conan Doyle apparently got bored with Watson as narrator. Two of the last stories he wrote, "The Adventure of the Blanched Soldier" and "The Adventure of the Lion's Mane", are narrated by Holmes and do not feature Watson at all. Two more of the later stories, "His Last Bow" and "The Mazarin Stone", are told from a third-person POV. They are the only stories in the canon where Sherlock's adventures are told in third person.
Old Friend: After being essentially absent for 6 books, Tobias Gregson treats Holmes like one when they meet up in "The Adventure of the Red Circle".
On One Condition: In "The Three Garridebs", a will stipulates that a man with the extremely rare surname Garrideb will inherit a property provided that he can find two other people with the same surname. The property will be split between the three of them. However, just two Garridebs would get nothing. The trope turns out to have been purposefully invoked by the villain, who made the whole thing up for his own purposes.
Only a Flesh Wound: Subverted. Doyle (unsurprisingly given that he was a doctor) accurately treats Watson's wound in Afghanistan as highly physically debilitating. Unfortunately, he could rarely remember exactly where the wound was...
And then there's the time in "The Three Garridebs" when it was only a flesh wound, giving us a Crowning Moment of Heartwarming when we see Holmes really and truly frightened at the thought of Watson being hurt.
Only Friend: Holmes's idiosyncracies and general lack of interest in other humans except as puzzles ensures that Watson is his entire social circle.
Opium Den: Watson goes to one in "The Man With the Twisted Lip" to retrieve a friend who has become an opium addict. He there finds Holmes, who is there on a different case.
Orgy of Evidence: In "The Adventure of the Norwood Builder", there is already considerable evidence incriminating the suspect in the eyes of the police, but the clincher is a bloody thumbprint of the suspect on the wall. Holmes finds this suspicious, especially as he had carefully searched that hall the day before, and there had been no bloody thumbprint there, making the clue in his eyes proof that it was a setup.
Overshadowed by Awesome: Watson, who is intelligent and capable in his own right; he just pales in comparison to Holmes.
Pinkerton Detective: In "The Red Circle" one has come from America to catch an Italian criminal.
Police Are Useless: In the early stories, the men of Scotland Yard were a collection of incompetent dullards who'd have trouble catching a cold, much less a criminal. In The Sign of the Four Holmes proclaims "I would rather have the help of Toby (a dog) than the entire detective force of London!" Holmes' dim view of the police was actually Truth in Television at the time, such as fouling up the investigation of the Jack the Ripper murders, and as the real-life police took steps to improve their investigative techniques, their depictions in the stories also improved to the point where Inspector Gregson was praised for his courage and Inspector Lestrade was a more thorough investigator who simply lacked Holmes' Hyper Awareness. The police were also generally portrayed as having their own merits and being capable of solving the everyday cases that were beneath Holmes' notice. However, in "The Adventure of Wisteria Lodge", the country detective Baynes is nearly up to Holmes' standard for observation (finding and analyzing the crumpled note in the fireplace) and tactical cleverness (the false arrest). Holmes handsomely congratulates him, saying "You will rise high in your profession."
Professor Guinea Pig: In "The Adventure of the Devil's Foot", Holmes' working hypothesis is that some unusual ashes he discovers become, when burned, a powerful poison. He tests his hypothesis... by burning the ashes while Holmes and Watson sit down and find out if they get poisoned or not. Holmes does take precautions, but even so appears to underestimate the possible potency of the poison, and only quick action by Watson saves both of their lives.
The Profiler: Both Holmes and Watson often fancy themselves to be this, sometimes correct and sometimes not.
In "The Adventure of the Red Circle", someone places ads in the London Daily Gazette' "agony column" to send secret messages.
"The Adventure of the Bruce-Partington Plans" also features messages in an agony column as a clue, this time in the Daily Telegraph.
In "The Adventure of the Dancing Men", a series of dancing stick figures appeared in several locations visible to anyone who passed by. Holmes decides the figures represent letters and decodes the message.
Purple Prose: Holmes accuses Watson's writing style of being this.
Put on a Bus: Poor Mary throughout most of The Memoirs. Then, in "The Empty House", we're given an indirect indication that the bus crashed.
Rail Enthusiast: Watson can recite the rail schedules off the top of his head.
Real Fake Wedding: Inverted in "The Adventure of the Solitary Cyclist", where the groom claims the pastor (and therefore the wedding) was legitimate. Holmes replies that even if the pastor was real (doubtful at best) the forced wedding won't hold up in court.
Recursive Canon: Watson and Holmes are both aware in-universe that Watson is writing and publishing stories about Holmes's career. Holmes disapproves of the sensationalistic tone of Watson's stories.
Remember the New Guy: Professor Moriarty is introduced in "The Final Problem", written after two novels and two prior short story collections, as the archnemesis Holmes has been hunting for years.
Retcon: Remember that for seven years after "The Final Problem" was published, Holmes was dead, then the fandom bugged Arthur Conan Doyle enough that he wrote "The Empty House".
It is implied that Watson does this all the time to avoid lawsuits.
"The Adventure Of The Second Stain" is first mentioned in "The Adventure Of The Naval Treaty". Watson recounts how it involved so many of Britain's highest noble families, and involved Holmes explaining the true solution to the French detective M. Dubuque and the German detective Fritz Von Waldbaum. The version of "The Adventure Of The Second Stain" that is actually published is a completely different story.
Sacrificed Basic Skill for Awesome Training: In the first story, it's revealed that Holmes has no literary knowledge beyond modern crime literature, and when Watson explains the makeup of the solar system to him, he is interested, but immediately comments that he will "do his best to forget it." Why? Because Holmes reasons that there is only so much you can hold in your head, and he needs only what is required for his profession. This was later ignored by Doyle. Despite apparently having nil knowledge of literature, Holmes is able to quote Johann Wolfgang von Goethe in the original and is familiar with Thomas Carlyle. Perhaps Holmes just had one of those "famous quote each day" novelty calendars?
Scare 'Em Straight: This trope is Lampshaded by Holmes when he lets James Ryder go in "The Adventure of the Blue Carbuncle". Holmes notes that Ryder is already a nervous wreck after everything he's been through, and that he's too scared to ever commit a crime again. Putting Ryder in jail would only making him a jailbird for life, but letting him go after very nearly being ruined will keep him from ever doing wrong again. In any event, the greater good would be served since Holmes would be able to ensure the man Ryder framed would be found innocent of the crime.
Scooby-Doo Hoax: Every single time Holmes encounters a "supernatural" phenomenon, he will use his deductive powers and knowledge of esoteric elements to determine not only that it was a hoax, but exactly how it was done. The Hound of the Baskervilles is perhaps one of the most famous examples.
Screw the Rules, I'm Doing What's Right: Holmes LOVES this trope. Made particulary clear in "The Disappearance of Lady Frances Carfax" where he convinces someone to wait for the police (which would take 24 hours to get a warrant) before breaking and entering the house of a conman in search of his kidnapped loved one... only for him and Watson to arrive to the conman's house and hold him at gun point while they search for the kidnapped person.
"Where is your warrant?" Holmes half drew a revolver from his pocket. "This will have to serve till a better one comes." "Why, you are a common burglar." "So you might describe me", said Holmes cheerfully. "My companion is also a dangerous ruffian. And together we are going through your house."
Secret Relationship: This turns out to be at the bottom of "The Adventure of the Missing Three-Quarter"; the missing man is secretly married to a woman of a lower social class, and can't reveal it or his uncle will disinherit him. When she becomes fatally ill, he simply disappears so he can go to her without having to explain.
Sentenced to Down Under: This is what happened to a character in "The Adventure of the Gloria Scott". However, he and his fellow convicts rebel and seize control of the ship before they reach Australia.
"The Adventure of the Three Garridebs" uses this for a plot point. Holmes is able to divine from the spelling of the word "plow" (in British English, "plough") and a couple of vocabulary choices that an advertisement purportedly from an Englishman is actually from an American.
Used for humor in "The Adventure of the Noble Bachelor"
Lord St. Simon: Lady St. Simon said something about ‘jumping a claim.’ She was accustomed to use slang of the kind. I have no idea what she meant.
Holmes: American slang is very expressive sometimes.
In "His Last Bow", Holmes, who has disguised himself as an American, expresses his contempt for American vocabulary.
Holmes: I shall no doubt reappear at Claridge’s tomorrow as I was before this American stunt — I beg your pardon, Watson, my well of English seems to be permanently defiled — before this American job came my way.
Sometimes Watson's war wound is in his shoulder, and sometimes it's in his leg.
In "The Adventure of the Twisted Lip", Mary Watson calls her husband "James".
In "The Final Problem", Watson doesn't know who Moriarty is, so Holmes has to explain it to him. However, in "The Valley of Fear", which was written after "The Final Problem" but takes place before it, Holmes already informs him about Moriarty and his terrible deeds, so Watson should've known about him in "The Final Problem".
In the "The Adventure of the Naval Treaty", Watson refers to another case he hasn't yet written about, "The Adventure of the Second Stain". He mentions some interesting facts about the case, specifically that the case "implicates so many of the first families in the kingdom that for many years it will be impossible to make it public", and that it involved "Monsieur Dubuque of the Paris police, and Fritz von Waldbaum, the well-known specialist of Dantzig, both of whom had wasted their energies upon what proved to be side-issue". "The Adventure of the Second Stain" was finally published 11 years later, but it turns out that only one "first family" was implicated in the case, and there's no mention of Dubuque or Waldbaum in the story, nor does it seem very likely that anyone in Paris or Dantzig was ever involved in investigating the case.
Sharp-Dressed Man: Holmes liked to dress well and, as noted above, in the books would never wear countrywear in the city.
Sherlock Scan: The Trope Namer - Sherlock's favorite marketing shtick, a perfect means to impress potential clients as to his skills.
Shout-Out: Holmes often tosses off a pithy quotation at the end of the early stories. Goethe is a favorite source.
Sliding Scale of Continuity: The stories can be read in any order (with a very few notable exceptions like The Final Problem and The Empty House). And after the first few stories, they aren't all set in the order they were written in, anyway. Conan Doyle deliberately wrote them like this so that readers would not quit following the series just because they had missed a story or two.
Snakes Are Evil: Holmes compares Moriarty's shifty gaze to that of a snake. When describing Milverton, a particularly odious blackmailer, he claims he gets the same impression as when looking at the snakes at the zoo.
Spanner in the Works: "The Adventure of the Naval Treaty" features Joseph Harrison, the brother of Percy Phelps' fiancee stealing an important treaty. He hides it under the floorboards in his bedroom, intending to sell it to the French or Russian Embassies later, but before he can Percy comes home after suffering a nervous breakdown over the treaty's theft. Joseph ends up kicked out of his own room, where Percy goes to rest, and the treaty remains hidden under the floorboards where Joseph can't reach it. This prevents the treaty from being sold long enough for Percy to recover from his fever and enlist the help of Holmes.
Spin-Off: Recurring characters Mycroft Holmes, Irene Adler and Lestrade all have their own authorized series of non canonical books, with varying degrees of success.
Lestrade: I find it hard enough to tackle facts, Holmes, without flying away after theories and fancies.
Holmes: You are right, you do find it very hard to tackle the facts.
A Storm Is Coming: "His Last Bow", which was written in 1917 and set in August 1914 just a few days before Britain's entry into World War I, ends with Holmes anticipating what is to come.
Holmes: There's an east wind coming, Watson.
Watson: I think not, Holmes. It is very warm.
Holmes: Good old Watson! You are the one fixed point in a changing age. There's an east wind coming all the same, such a wind as never blew on England yet. It will be cold and bitter, Watson, and a good many of us may wither before its blast. But it's God's own wind none the less, and a cleaner, better, stronger land will lie in the sunshine when the storm has cleared.
Strictly Formula: Not the stories themselves, but Watson notes on reading a newspaper article about a divorce that he already knows what it's about: a drunken husband, who pushes his wife one time too many, and a sympathizing landlady. But in this case, he's Wrong Genre Savvy: Holmes was involved in the case because the husband was in the habit of throwing his false teeth at his wife.
The Stoner: Cocaine, naturally. Holmes only does it whe he's bored.
Talk About the Weather: Lestrade resorts to this once, where the case is very odd and he's not sure he should tell Holmes.
Techno Babble: In "The Missing Three-Quarter", the captain of a football team rattles off a massive speech of football terms that explains why his team is screwed if Holmes doesn't find his missing three-quarter.
Thanatos Gambit: In "The Problem of Thor Bridge", the wife, jealous of the governess that her husband has fallen in love with, rigs up an elaborate suicide that is intended to frame the governess for murder.
Total Party Kill: The fate of all the honest crew on the Gloria Scott and then a second time shortly afterwards, with the mutineers, as well as the entire ship.
Treasure Map: "The Adventure of the Musgrave Ritual". However, given that the map's directions gave the starting point derived from the shadow of one tree when the sun was above a second tree as they were nearly two and a half centuries before the map was used (They would have grown, changing both the angle of the sun and the length of the object casting the shadow - given that they weren't the same kind of tree, they might not have grown at the same rate, further complicating the issue), and the directions were given in the highly inaccurate paces (Holmes has noted that the length of a man's pace is directly related to his height many times, and the idea that Holmes' legs are the same length as the legs of the man who made the map is a bit of a stretch, even if it was noted the man who followed the map was rather tall), the fact that they actually found the treasure is rather surprising.
Truth In Literature: Doyle himself would go on to investigate, Sherlock Holmes style, the cases of two men who had been wrongly imprisoned and found the evidence to set them free.
The examination of a victim's clothes for clues and the use of plaster to make impressions of marks on the ground was first done in the stories and later became real-life procedure.
Unexpected Inheritance: A major part of The Sign of the Four and "The Adventure of the Solitary Cyclist". A fake one is used in "The Adventure of the Three Garridebs".
Considering Watson openly admits to having mixed up narratives in ordinary conversation at a tense moment (e.g. firing a tiger cub at a double-barreled shotgun rather than vice versa), it could be argued that he accuses himself of being one, too.
Unspoken Plan Guarantee: Setting up culprits to incriminate themselves, Holmes never lets Watson or the police in on what he's planning. Often, they (and readers) don't even have any idea which culprit he's expecting will show up.
Note that "A Scandal in Bohemia", Holmes' most well-known failure to catch a culprit, involves Holmes telling Watson and his client his plan in exact detail, only for it to be foiled.
Unbuilt Trope: By now, even ardent fans of the series are used to the classic image of Holmes as the genius "superhero detective" who stands up for justice and battles criminals and evil geniuses. The series shows many tropes that are now familiar in the genre.
Defective Detective - Holmes eccentricities are portrayed very differently from more modern depictions of the detective. While the modern Defective Detective can credit much of their forensic skills to their eccentricities, they also at times hinder the detective.
Forensic Drama - Holmes simply explains all of his forensic analysis at the end, with the reader seldom privy to intermediate steps.
Police Procedural - Sherlock Holmes, a private detective, is seldom described doing the same procedure exactly the same way. He is also wildly inconsistent on whether or not he does detailed interviews of witnesses. The police, who do follow a set procedure, generally don't get the job done.
Villain with Good Publicity: No one could believe Moriarty was a master criminal even when "The Final Problem" was published. According to Watson he only published an account of his dear friend's death because, thanks to Moriarty's brother, people still didn't believe he was guilty. Moriarty was described by an Inspector as being "a very respectable, learned, and talented sort of man" and even went as far as saying that "When he put his hand on my shoulder as we were parting, it was like a father's blessing before you go out into the cold, cruel world." Holmes couldn't help but chuckle at the irony.
The Watson: The Trope Namer. Watson virtually never guesses what is going on or makes a correct deduction of his own, but instead serves to ask the reader's questions and make Holmes look good. Lampshaded by Holmes in "The Blanched Soldier".
Holmes: A confederate who foresees your conclusions and course of action is always dangerous, but one to whom each development comes as a perpetual surprise, and to whom the future is always a closed book, is indeed an ideal helpmate.
We Help the Helpless: Holmes sells his services to anyone and everyone, from the poorest pawnbrokers to the wealthiest kings. Helping some of his university classmates with their dilemmas inspired Holmes to do it for a living.
What Happened to the Mouse?: The Baker Street Irregulars are called on in the first two novels, and are never seen again. The authorized pastiche The House of Silk endeavors to explain this.
White and Gray Morality: In "A Scandal In Bohemia", "The Man with the Twisted Lip", "The Noble Bachelor", and "The Yellow Face", it is revealed that there is no villain, and the apparent victim turns out to be the morally gray character.
Whole Episode Flashback: "The Adventure of the Musgrave Ritual" and "The Adventure of the Gloria Scott" . Three out of the four novels also feature this, namely A Study in Scarlet, The Sign of the Four, and The Valley of Fear. This is mostly the reason why The Hound of the Baskervilles became the most filmed Canonical story ever and consequently the most famous.
Worthy Opponent: In The Adventures Of Sherlock Holmes, we have John Clay in The Red-Headed League, who is so hard to catch that he and Holmes never see each other until the story. This trope kicks in near the end-Clay outright praises Holmes for his arrangements and quick thinking, while Holmes compliments Clay for his excellent scheme and how close it came to succeeding. Furthermore, although Clay is outright rude to Inspector Jones, he bows to Holmes and Watson as he heads off to jail.
Irene Adler, the only woman to pwn Holmes to date. She's also succeeded in making him develop feelings for her-he never does so for any of his female clients, and he always refers to her as "The Woman."
Also, Professor Moriarty: at their fateful last encounter, gentleman Moriarty lets Holmes write a farewell letter to Watson before starting their fight to the death, and Holmes knows he can trust Moriarty to wait patiently until the letter is finished and not to push him into the nearby falls while his attention is on the paper.
Year Zero: Holmes is revealed to be 60 years old during 1914 which effectively gave him a birth year (1854) and an age (27) during A Study in Scarlet (March 4, 1881).
Similarly, Watson's date of graduation from medical school (1878) gives him a birth year of either 1852 or 1853 and an age (probably 28, possibly 29) in A Study In Scarlet, assuming he did not take time off during his education.
You Do Not Have to Say Anything: In "The Norwood Builder" Lestrade tells a suspect that “I am bound to warn him that anything he may say will appear in evidence against him.” In "The Dancing Men" another policeman reads the same warning to a suspect.