Accidental Nightmare Fuel was just called "Nightmare Fuel" for a long time, and Nightmare Fuel was "High Octane Nightmare Fuel" (and even before that, "Nightmare Fuel Unleaded"). The former was renamed since people often kept using it as things intentionally made scary, which was High Octane Nightmare Fuel at the time, or things which they personally found scary, which really doesn't belong on a general-purpose Nightmare Fuel page. "High Octane" then assumed the old name "Nightmare Fuel" after suffering major Trope Decay.
Acting In The Dark used to be "Karim the Assassin", a nickname of Karim Zreik, co-executive producer of Harper's Island. Readers who did not know the story behind his nickname could not link the title to actors being unaware of their character's future.
Actor Allusion was formerly "The Alkazar" after a Futurama gag. It was renamed because of obscurity even with fans of the show. Also, the Futurama character was called Alcazar. To understand the gag, you had to remember that the actor playing Leela was also the mom on Married... with Children, and was being paired opposite her character's husband.
Actor Role Confusion once was "Your Secret's Safe with Me, Superman". Renamed because the old name referred to an example where the fan even gets the role wrong.
Adaptive Ability was previously "Viva la Evolution", but was misnamed because the previous title was non-indicative and misleading.
Adventure Duo was launched as "Adventure Couple", which led even mods to think that the trope was about actual romantic couples adventuring together, rather than describing a particular set of personalities common to Hero/Lancer pairs.
Alpha Bitch was originally named "The Libby" after a character in Sabrina the Teenage Witch. This, obviously, was problematic, since she was only around for a few seasons, not to mention it was a character-named trope, which isn't really in this wiki's best's interests. The former Trope Namer also failed the One Mario Limit for sharing her name with characters from various other works.
Always in Class One was "Class is in Room X01", but that name was found to be far too vague and non-indicative.
Ambition Is Evil was named "Slytherin House", after the Harry Potter group and its typical portrayal. However, the trope itself was not about groups.
Anatomically Impossible Sex was "Artistic License - Sex Ed", and before that You Fail Sex Ed Forever. It got caught up in the mass rename of the "You Fail X Forever" tropes to "Artistic License - X", even though it didn't fit into the new naming scheme.
Anatomy Of The Soul was once "Dream Mirror". It is not about mirrors or about dreams per se. The old title required familiarity with Sailor Moon, using the name of a piece of Soul Anatomy unique to the work.
Anger Born of Worry was renamed from "Fear Leads to Anger" because the trope was fairly unrelated to the phrase from Star Wars that served as its former name.
Animal Athlete Loophole used to be "Ain't No Rule", an overly general title that caused it to be routinely mistaken for its supertrope, Loophole Abuse, rather than twisting the rules to get an animal into a sporting competition. The old name is now an alt-title for Loophole Abuse.
Animal Nemesis was renamed from "Pick on Someone Your Own Species" for clarity and in order to discourage misuse of the trope for examples that did not feature a human trying to take revenge on an animal.
Animation Tropes used to be "Animated Trope". The index got renamed to what people would naturally call its contents in English.
Arbitrary Maximum Range was once known as "Space-Based Weapon Has Cutoff Range". Renamed because someone complained it was way too long. The funny thing is that the old one was launched for nearly a year before someone started complaining, even though the launcher asked for a better name in the YKTTW.
Arc Fatigue was "Are They Still on Namek", which is meaningless for people who didn't see the show.
Archer Archetype was "Straight Arrow" and was turned to "The Archer" when it was determined that Straight Arrow was better used metaphorically. Until it was determined the trope was being used to refer to weapon usage rather then character traits, then it was changed to Archer Archetype.
Artistic License - X articles were once "You Fail X Forever" or "X Does Not Work That Way" or "Somewhere An X Is Crying". Renamed to be more neutral.
Artistic License - Ships was previously "Failed to Pay Shipping Charges", and was renamed to make it clearer what the trope was actually about.
Artistic License - Military was originally "You Fail Basic Training Forever" before it got custom titled into "Artistic License - Basic Training". However, because the trope covered more than just Basic Training and the term "Basic Training" failed to specify what type of training, it was changed to the current name.
Asbestos-Free Cereal used to be "Made with 100% Pure Grade-A Crap". The title was renamed for being too negative.
Ascended Extra was formerly known as "Super Grape". Renamed mostly because Super Grape barely made sense even when explained.
Ascended Fanon was renamed from "Sure, Why Not?" because it sounded too similar to Sure, Let's Go with That and/or otherwise sounded like a stock phrase. The new title has the bonus of fitting in nicely with the other "ascended" tropes.
Ashes to Crashes was initially termed "Chekhov's Ashes". As well as being a rather overused snowclone, Chekhov's Gun style tropes need to be a side detail that becomes important later: too many examples have the ashes front and center. The new name gets the idea across directly.
Awesomeness Is a Force was renamed from "Pure Awesomeness" because the old name didn't make it clear it's about awesomeness being described like a physical ability.
Awful Wedded Life was formerly "No Exit" after Sartre's play of the same name, which wasn't even an example. And as Blondie fans will tell you, No Exit is also the title of at least one work other than the Sartre play, hence is ineligible as a trope name anyway.
Bacon Addiction was originally called "Everything's Better with Bacon" according to the discredited and completely unrelated "Everything's Better With X" snowclone family.
Badass Decay was formerly known as "Spikeification", after Spike from Buffy the Vampire Slayer. It was changed because it required familiarity with the work to be understood (and there were debates over whether Spike was even an example), and because it could easily be assumed to refer to the process of making things spikey.
Badass in a Nice Suit was originally "Dressed to Kill". The word "dressed" was too vague, and the word "kill" was too specific, leading to the misinterpretation that this was about an assassin who wears fancy clothes or a costume when working, rather than being about any ol' badass who wears a business suit or tux to look sharp or professional.
Bad News, Irrelevant News used to be "Switching to Geico", which itself was shortened from "I Just Saved a Bunch of Money on My Car Insurance by Switching to Geico" because overly-long titles are hard to type right.
Bad Writing Index was formerly "Bad Writing", which enjoyed massive misuse for complaining.
Basso Profundo was originally named "The Dish Rattler". It was renamed due to failure to thrive after over a year.
Bears Are Bad News used to be "Everything's Worse With Bears", a snowclone of the discredited "Everything's Better With X" family. It was changed when it was being used on any bears, regardless of how threatening they are.
Bee Afraid was merged from "Everything's Worse with Bees" and "Gosh Hornet" because the former was part of a discredited snowclone family and the latter was too indistinct from the former.
The Bechdel Test was formerly known as "Bechdels Rule". Arguments over whether the "rule" was being broken in various works got the name changed to emphasize the testing of a work. Now moved to Useful Notes.
Behind a Stick used to be "Narrow Escape". It was renamed for having nothing to do with the common meaning of that phrase, or, for that matter, with escapes at all.
Belligerent Sexual Tension was known for a while as "When a Jerk Loves a Tsundere". Before that, it was briefly known as "Tsunderes in Love" before it was decided as a misleading title since a jerk is not a Tsundere. Before that, it used to be called a "Takahashi Couple", named for mangaka Rumiko Takahashi (whose works are known for prominently featuring such relationships), a name dropped when specific references in titles fell out of fashion. Takahashi Couple now covers detailed examples from Takahashi's works.
Bespectacled Bastard Boyfriend used to be "Spectacled Sadist"; it was renamed because of confusion with Four Eyes, Zero Soul. Before that, it used to be "Kichiku Megane". That title gave no information to those outside the anime/manga fandom, or to those within the anime/manga fandom who hadn't come across the trope. It was also the name of a yaoi eroge Visual Novel, necessitating a rename to avoid confusion.
Best Her to Bed Her used to be "The Red Sonja". It was renamed due to misuse, and because the trope only constitutes one of the traits of the Trope Namer.
Big Bad Wannabe was "Evil Frog Who Wants to Be an Ox", a title that is quite awkward in a sentence due to its length, requires more typing than ideal, and is not immediately connected to its subject unless the reader knows the specific Aesop and applies it correctly.
Big Bulky Bomb used to be "BFB". It was renamed for being a confusing snowclone of BFG.
Big Damn Movie was formerly "Why Is Arnold Saving Something" after the occurrence of this trope in the Hey Arnold! movie. It was renamed because the name Arnold could refer to multiple people (such as Mr. Schwarzenegger or Mr. Rimmer).
Bigger Is Better in Bed was formerly "Biggus Dickus", a reference to Monty Python's Life of Brian. It was renamed because the Trope Namer was not actually an example of the trope in question, leading people to think that the trope was about joke names rather than large penises themselves. It also clarifies that the trope is about the connection between size and sexual performance, not just large size on its own.
Bizarre Instrument was previously "Xenophone", which was deemed not clear and indicative enough and led to misuse of the trope.
Bizarro Episode was once two different tropes, "BLAM Episode" and "A Day at the Bizarro". When the former was up to rename for being a confusing acronym, the latter was merged into the new trope.
Black Comedy absorbed "Dead Baby Comedy". The latter name is better known as a term for Vulgar Humor, leading to confusion.
Braces of Orthodontic Overkill was formerly "Lisa Needs Braces" for a mildly memetic early The Simpsons quote. It was changed because the latter is somewhat obscure and the former much more descriptive of what the trope is about.
Breakout Villain was formerly The "Moriarty Effect". It was renamed because the first association with Professor Moriarty is criminal masterminds. Also, Moriarty was deliberately introduced as an archenemy, making him a less than ideal example. Finally, any Breakout Villain has a tendency not to be known as one because they are one — see Breakout Character.
Breath Weapon was formerly "Beaming Grin" after a pun on the facial expression.
Bring It used to be "Bring It On", but was shortened to distinguish it from the movie Bring It On.
Bring My Red Jacket was formerly "Bring My Brown Pants". The name was changed to use the line from the joke/song that actually applied to the trope, and to free up Bring My Brown Pants for use on the trope that it fits: soiling or wetting oneself from fear.
The Bronze Age of Comic Books was formerly known as "Bronze Age". It was renamed because not only did it need to be changed to match the new names for Golden Age and Dark Age, but there were also references to the concept of a Bronze Age independent of comic books.
Building of Adventure was once "Xanadu", from a large mansion in Citizen Kane. This somewhat obscure reference was not an example of the trope, since the film has several settings. Additionally, many folks assumed it linked to Xanadu.
Built With LEGO was originally called "Everything's Built With LEGO", according to the discredited and completely unrelated "Everything's Better With X" snowclone family.
Bulk Buy Only was "Midnight Bakery Trip". The name neither indicated the trope nor fit the Trope Namer (some bakeries sell goods at lowered cost the next morning, but only if bought in dozens).
Bunny Tropes used to be Everything's Better With Bunnies. It was broken up into several tropes and turned into an index of rabbit related tropes.
But Not Too Foreign was originally known as "Charlie Dog", after the Looney Tunes character, renamed to be clearer (you'll be hard pressed to find even fervent Looney Tunes fans who would know that the trope applies to said character).
Career Building Blunder was "House Hiring Heuristic", after the lead of medical drama House who followed the trope several times. But it's not hiring: it's promotion or other increases in trust and responsibility following a bad mistake — something not apparent from the title. It also required specific work knowledge of the word "heuristic" for rule of thumb, which was tripping some folks up.
Casanova Wannabe used to be "The Leisure Suit Larry", from Leisure Suit Larry. The too-close names led to roughly half the Leisure Suit Larry links mistaking the game for the trope. (Originally the trope name was actually the same as the game, without the definite article.) Also, Larry is not a Casanova Wannabe: he always ends up with many conquests. He has to be the opposite, a Kavorka Man, for the games to work.
Catastrophic Countdown used to be "Metroid Bomb", providing no information to those outside a very specific fandom. Even within the Metroid fandom, there are several bombs it could be, whereas this trope refers to the interesting kind of timebomb that causes the surrounding area to join in with sympathy explosions even before it goes off.
The Chosen Many used to be "Green Lantern Corps". Slightly over half the uses of it assumed it was an article on the the fictional organisation rather than the trope centering on a band of chosen ones. Additionally, the old title didn't convey much to those unfamiliar with Green Lantern works. Green Lantern Corps now redirects to Green Lantern.
Chuck Cunningham Syndrome was originally "Brother Chuck", changed to indicate that it was more about a phenomenon than an actual character type.
Cynicism Catalyst was renamed from "Dead Little Sister" for being massively misused for dead siblings.
Circling Monologue was "Circle of Extinction". It was changed to improve its clarity in hopes of attracting better usage.
Civilian Villain was previously named "Civillain" and was renamed for clarity since the pun in its title was far from obvious.
Coincidental Dodge was originally "Gardener Contract". It was named after Chance, the gardener from Being There, despite not actually having a failed assassination attempt foiled by coincidence in the movie. note The link was Chance being a very lucky fool mistaken for someone important — the type of character who is sometimes subject to Coincidental Dodge comic scenes.
Combined Energy Attack used to be "Spirit Bomb", named after a technique used by Goku in Dragon Ball. Renamed because the trope namer caused the definition to be too narrow and some tropers thought the trope was "a weapon to attack someone's spirit" instead of "group pools their energy for a attack or other purpose".
Comically Missing the Point used to be "Completely Missing the Point". It was changed because too many people misunderstood the intention of the trope (a character missing something obvious for comic effect) and would use it in an accusatory manner against anyone or anything they disliked or disagreed with.
The Comically Serious used to be "Unfunny" (and previously "The Unfunny"). It was changed to more clearly indicate that the trope is about a serious-minded person being put into comical situations, and the contrast being Played for Laughs, rather than something or someone which tries to be funny and fails.
Confirmation Bias was renamed from "Preaching to the Choir" because the trope was using that phrase different than how it is commonly used and was encouraging misuse for the normal meaning.
Confusion Fu used to be "Schr÷dinger Fu", which was named from Schr÷dinger's Cat — a thought experiment from quantum mechanics where a macroscopic object is in two states simultaneously while unobserved. The idea was to suggest randomness via quantum randomness. But the trope is a fighting style built from erratic, unpredictable movements: the fighter isn't splitting into multiple versions which influence one another while unseen.
Constantly Curious used to be "Elephant's Child". It was named after the main character in a short story by Kipling, and not very descriptive.
Consulting Mister Puppet used to be "Consulting Mr. Flibble" — a name with little meaning to those unfamiliar with Red Dwarf. The new name invokes the most common scenario directly.
Consummate Liar was renamed from "Liar Liar" to avoid confusion with the movie of the same name and as a side benefit to be more specifically connected to the trope.
Contractual Purity used to be "Prisoners of Pollyanna", but was too easy to confuse with The Pollyanna and also assumed that people understood to which Pollyanna the name referred.
Counterpart Comparison used to be "Why Does Everyone Think I'm Deadpool?" It was renamed because the trope name was needlessly wordy, in addition to being from an obscure source.
Cover-Blowing Superpower used to be named "Awkward Ability", but was renamed because the previous name created confusion about the power itself being awkward rather than the cover-blowing effect of that power.
Crapsack World existed for a long time, absorbed "Sick Sad World", which is from Daria, and then "A World Half Empty", as both were deemed The Same but More Specific. It also absorbed "World of Woobie", which is one of its characteristics turned into a trope.
Creator's Pet was "The Wesley" for a long time. Renamed for being a character-named trope (which led to misuse due to tropers thinking that it was "The Scrappy, but moreso"), as well as failing the One Mario Limit, since there are characters from various other works who share his name.
Credits Running Sequence used to be "Running Sequence". It was renamed to clarify that the trope occurs during the credits.
Creepy Cockroach was originally titled "Everything's Creepier with Cockroaches", a snowclone of the discredited "Everything's Better With X" family. As with several similarly named tropes, the earlier name encouraged a list of all roaches regardless of portrayal.
Criminal Mind Games was renamed from "Along Came a Spider" so as to avoid having a trope named after a work.
Criminal Procedural was renamed from "Crime Time TV" because it was both underused and unnecessarily medium specific.
Crowded Cast Shot was renamed from "Everyone Get in Here" for clarity and in order to avoid using a stock phrase.
Cruella to Animals was renamed from "The Cruella" to emphasize which aspect of Cruella DeVil's character exemplified the trope. As a valuable bonus, those who know not of Cruella shall gain purchase on the meaning via the pun.
Cruel Twist Ending was renamed from "Outer Limits Twist", not only because the original name came from a work, but to prevent confusion between the two versions of that work.
Crutch Character was renamed from "Jeigan Character" since Jeigan is not well known outside the Fire Emblem fandom. The old title essentially conveyed no information to readers outside this community, not to mention Spell My Name with an "S" issues (since the character's "official" English name is Jagen).
Cutaway Gag used to be "Manatee Gag". It was renamed for several reasons (it was a Take That on a South Park episode that parodied Family Guy; the name was incomprehensible to anyone who never watched said episode, and the term "cutaway gag" is commonly used elsewhere). Funnily, the trope actually wasYKTTW'd as Cutaway Gag, but somehow got launched with that name.
Cute and Psycho was originally "Yangire", which is used by the anime fandom to describe this kind of character and is not an actual Japanese word.
Cute Clumsy Girl was formerly "Dojikko", the term used within anime fandom to mean the same thing. As of this writing, Dojikko is an official subtrope of Cute Clumsy Girl, with its own trope page.
Cute Kitten was originally titled "Everything's Cuter with Kittens", a snowclone of the discredited "Everything's Better With X" family. As with several similarly named tropes, the earlier name encouraged a list of all kittens regardless of portrayal.
Cut Short was originally called "Woody's Finest Hour" after a scene from Toy Story 2, but was changed for better clarification.
Danger Room Cold Open was called the long and unwieldy "Professor X Likes to Watch Teenagers Sweat", which was also loaded with (probably not unintentional) implications that make you think of a different trope.
The Dark Age of Comic Books was formerly known as "Dark Age". It was renamed because not only are there dark ages for other media, but there were also references to the concept of a Dark Age independent of comic books.
Dark Horse Victory was formerly "Zmelik", after an Olympic athlete (namely, the one that actually won the Decathlon gold in 1992, the year of "Dan vs. Dave").
Dark Mistress was formerly "Doctor Girlfriend" after the character from The Venture Bros.. Renamed due to the fact that there are several qualities of the "good" Doctor that could've attached to the trope and no way to figure out which was applicable from just a glance.
Dashing Hispanic was renamed from "Badass Spaniard", which was judged too broad as it didn't cover any of the specifics involved in the trope (including a sense of honor, wit, grace in battle and romance).
Dated History was renamed from "History Marches On" because of widespread misuse for history-related inaccuracies.
Debut Queue was "Ducks in a Row". The link between getting organized when starting a new project and introducing characters one by one was too much of a stretch for most readers; and the related meaning of the expression, to line things up one after another (like duck-pins), was easily confused with All in a Row.
Decoy Trial was formerly known as "Trial of Someone Besides the Defendant", which was a mouthful.
Deep-Fried Whatever was originally titled "Everything's Better Deep Fried", a snowclone of the discredited "Everything's Better With X" family. As with several similarly named tropes, the earlier name encouraged a list of all deep fried things regardless of portrayal.
Deliberate Injury Gambit was formerly "I Have Two Kidneys". It was renamed because the old title did a poor job of describing what it was about.
Delusions of Eloquence was "Shlubb and Klump English", but got a rename due to it being a character-named trope.
Demoted to Extra was formerly "Isn't It Sad", which originated in a meme among fans of Tsukihime, in reference to the character Sacchin. Renamed because it was too obscure, not to mention that the trope title could easily be assumed to refer to any kind of sad situation in general.
Demythtification was "Low Low Fantasy", which makes it look like a direct extension of Low Fantasy: it is not. These stories aren't intended as members of the fantasy genre, but as an External Retcon of a myth to strip it of fantasy elements and render it as historical fiction.
Disco Dan was very briefly (one full day, and notone day more) named "Joe Quesada Reality", after the Marvel Comics executive who has acquired quite a hatred from the fans. It was changed because some people disapproved of the "bitter fan" vibe of the inherent Take That, and others said that the trope namer barely even fit the trope.
Down to the Last Play was formerly "The Casey Effect". It was changed because it implied the protagonist team always losing, and because it suggested that the trope was baseball-specific.
Do Wrong, Right used to be "This Is Not El Alamein", but the name was too obscure (El Alamein is a town in Egypt and a battle of World War II — what it has to do with this trope is further info that is required to understand it; thus the change).
Dramatic Slip was renamed from "I've Fallen and I Can't Get Up" to discourage misuse for the stock phrase and to encourage use for an otherwise underused trope.
Driven by Envy was "Salieri Syndrome", but the old name was too opaque and failed to attract wicks.
Drunk on Milk was formerly "Drunk on Malts". It was renamed because of the possible confusion of malts with malted hops when malts are meant to refer to a clearly non-alcoholic drink like milk.
Dub-Induced Plot Hole was originally "My Name Is Prince Darien", after a certain happening in the DiC dub of Sailor Moon. It also spent some time hitchhiking cross-country under the alias "Errors Through Localization".
Eccentric Mentor was originally named "The Dumbledore" after the character from Harry Potter. It was renamed because the character it was named after was known for other things than just the trope he was named for.
Egocentrically Religious used to be "Spoiled Brat of the Lord". Rather than a character actively being spoiled, this one is more about a egocentric mindset in worship. For some, Lord evokes nobility rather than a religious figure — and it's not specific to Abrahamic religions in any case. The new name presents both elements of the trope more clearly.
The Ending Changes Everything used to be "The Usual Suspects Ending", a name based around a specific movie, which revealed nothing to those unfamiliar with the movie and constituted a spoiler. Worse, the trope itself told readers at the very beginningnot to read the rest of the trope description unless they had seen the movie first.
Enigmatic Empowering Entity used to be "Empowering Lake Lady" and, in part, "Strange Pond Woman": the partial merge was rather involved. The old names were a reference to a famous example, the Lady of the Lake from the King Arthur mythos. The title was changed for being overly specific. Probably.
Enthralling Siren was renamed from "Our Sirens Are Louder" due to bad snowclone application.
Epic Battle Boredom was renamed from "Kicking Ass And Taking Names" due to disuse and clarity concerns.
Epic Movie was previously "BFM". Renamed for being an incomprehensible initialism and because Epic Movie is the generally used term for the concept.
Erotic Eating was formerly "Yum Yum", which (possibly) sounded too ambiguous.
Eureka Moment was originally named the "Creek Moment" after the British TV detective Jonathan Creek. Renamed because the term "Eureka" was far more searchable, "creek" will never be immediately known as a character name (as opposed to a location), and even those who knew of Creek didn't understand what a Creek Moment was.
Even Mooks Have Loved Ones was originally called "Even Evil Has Loved Ones". However, it was misused in over 80% of wicks on works and character pages as "evil person demonstrates genuine love for another" (which is what Even Evil Has Loved Ones now covers).
Excited Title! Two-Part Episode Name! was originally "Excited Episode Title!", which attracted lots of misuse as any title with an exclamation point when the trope is about a specific title convention.
Experimental Archeology was renamed from "Kon Tiki Plot" in order to broaden the meaning of the trope, clarify it, and encourage use for an otherwise underused trope.
Explaining the Soap was formerly "Soap on a Trope", but was renamed because it used "trope" as a placeholder and was overall non-indicative.
Exponential Plot Delay used to be "Zeno's Race", after an early mathematical theory of limits. The idea was a story that showed ever-greater plot delay could be metaphorically represented by Zeno's theory. In the theory, movement is impossible since no matter how many times you travel half a distance, you have an infinite number of half-distances to go. This was too much of a stretch for general readers.