Intentionally deceive Character A into believing that something that's less strange must actually be the truth if, for example, Character A is interrogating Character B, and Character B doesn't want a much larger secret to get out
To get Character A to stop asking them about it, if Character B doesn't want him/her to "know" the truth
Kid-Conan in the Detective Conan series knows about this problem, and solves it using a tranquilizer watch and a voice-changing bowtie to make it seem like someone more trustworthy in the eyes of the police is making all the deductions.
As is its fashion, Elfen Lied provides a particularly brutal example between Nana and Cute Mute Nyuu: Nana knows that Nyuu has an alternate personality called Lucy who is an Ax-Crazy mass murderer, but no-one else believes her.
Kouta's little sister Kanae risks her older brother's affections by insisting that she saw a horned girl kill people with arms that came out of her head at the Kamakura summer festival. Within about a minute of her saying this for the umpteenth time, Kouta is horribly made to learn that she wasn't lying.
In Haruhi Suzumiya, Kyon tells Haruhi about Itsuki, Yuki, and Mikuru's supernatural powers, and she flat-out doesn't believe him and tells him to stop messing with her. Then she makes the movie The Adventures of Mikuru Asahina Episode 00. It was not a coincidence, guys.
Happened during the arc that introduced Usopp. The villain ended up being well known in Usopp's town, and being a known liar, no one believed him.
Played for Laughs in the Fishman Island arc when Princess Shirahoshi is "kidnapped" and King Neptune believes Luffy did it. Brook comments he didn't see her leave, only seeing Luffy riding a shark (Megalo). Neptune believes he stuffed Shirahoshi into Megalo's mouth and rode out. The guards all laugh at this idea, but that's exactly what happened.
Quent in Wolfs Rain repeatedly fails to convince people that wolves are adopting human disguise for sinister purposes. He's right about the disguises, but wrong about the wolves' motivation.
Poor Rika in Higurashi: When They Cry. She tries to warn Tomitake and Takano, but do they ever listen to her? No; she barely comes up to their bellybuttons. (Actually, at one point Takano does seem to acknowledge Rika's foresight, but that's only because she knows what's going to happen; it's her Evil Plan.)
Light Yagami of Death Note subverts this several times, at one point "admitting" that he might be Kira so he can be locked up in order to prove that he isn't Kira and renounces possession of the Death Note so he can lose his memory, thus playing the role of innocent even more. It is all All According ToKeikakunote Keikaku means Plan.
In Full Metal Panic!, when Sōsuke explains to Kaname that he's a soldier from an elite military unit on orders to protect her, Kaname informs him that he's delusional — even as he's fighting off enemy soldiers and escaping with her across a military base. It's not until he climbs into an outdated Humongous Mecha and kicks a world of ass with it that she realizes he's telling the unvarnished truth.
In Mahou Sensei Negima!, Negi Springfield (though it is admittedly his fault) makes a good attempt at warning the other mage teachers about the existence of a Time Machine which could be used to Set Right What Once Went Wrong. Somehow, even full-fledged mages refuses to accept the idea of time travel. Also, nobody believes Chao the first time she tells everybody she's in truth "an alien from Mars." And still... Truth be told, Negi himself had it coming since the other mage teachers tried to convince him that Chao was on the verge of causing serious problems and he didn't listen to them.
Bleach: When Ishida first appeared in Soul Society, Mayuri realised that Soul Society was vulnerable to quincy attack and, because Yamamoto had failed to kill an old enemy in the past, a quincy attack is precisely what was going to happen. Yamamoto dismissed Mayuri's advice as paranoia. Boy, did that decision come back to haunt the old man!
In Axis Powers Hetalia, England can see magical creatures while only a few other nations can (Norway and Romania). Thus nearly every other nation thinks he's gone insane when they find him talking to the air. In one strip, France, trying to get England for a meeting, walks in and sees a mob of fairies, unicorns and gnomes surrounding a sleeping England, and his reaction is hilarious.
Bardock, from Bardock: Father of Goku is given the power to see the future. However, he sees their planet being destroyed by Frieza. Naturally, no one takes him seriously.
Nobody believes that Akihisa Yoshii knows how to cook because for those few episodes, we see him only eating sugar. Imagine everyone's surprise when he cooks paella.
Monster. Poor, poor Tenma. Try as he might, barely anyone will believe his story of a ten-year-old child committing serial murders.
Subverted in Fullmetal Alchemist. When Mustang is looking for some allies in the military brass, he mentions a few "strange rumors" to General Raven, including Scar liking cats and Furher Bradley being a homunculus. Raven brushes it off as a bad joke from Mustang. Then immediately subverted when Raven leads Mustang into the meeting with all the top generals and ominously asks him to continue his "joke". Sometimes not being believed is not as bad as being believed by the WRONG people.
Played straight in the first (non-manga) episode where the renegade Freezing Alchemist is trying to destroy Central City to stop a government conspiracy at the highest levels.
One of the most tragic examples comes when Lelouch, having just agreed with Euphie's terms behind the Special Administrative Zone, alludes to his power of Geass, but she doesn't believe him. He persists in giving more insidious possibilities of powers, until he just happens to be looking at her and says the wrong thing the moment Power Incontinence hits.
Also in season 2 episode 18 where Suzaku has a hard time warning Lelouch of the FLEIJA due to Schneizel having broken their friendship.
The creator of Gantz actually reveals the entire story of the Gantz operation to a reporter who confronts him for the truth. He then invokes this trope by saying that he told the entire truth because it's so outrageous that no one would believe anyone who exposed the story.
Puella Magi Madoka Magica has a tragic example in which Homura in the third time-loop tries to explain that Kyubey had been lying to the girls and has been orchestrated their transformations into witches. Not only does everyone not believe her, but when Sayaka finally does turn into a witch, the consequences lead to one of the worst events of all the loops.
Persona 4: The Animation has Yukiko and Rise telling Naoto all about the world inside the TV and Personae. Naoto doesn't believe them. Though admittedly, they were "drunk" at the time. Later on, Yu tells the police chief pretty much the same thing, and once again he isn't believed.
In Blue Exorcist, at one point Shura douses everyone in holy water to ward off demons - everyone except Rin, that is. When the others suspiciously question her visible hesitation, she answers that he's allergic to holy water, as ridiculous as that sounds. An episode later, the team is in a sticky situation when Rin unexpectedly announces that he was never good at lying and unleashes the signature blue Hellfire that's supposed to be the trademark of Satan. Another episode later, the kids find out what the audience already knew from episode two: Rin's biological father is none other than Satan himself, making him a half-demon. As Shura put it earlier, pouring holy water onto the poor boy wouldn't have been a pretty sight.
While fighting Loki in High School D×D, the protagonist Issei accidentally summons a breast god. No one believes him, not even when Ddraig had to explain that yes, he did hear the voice.
Kotoura-san is a Romantic Comedy that sets in an universe where... psychics actually exists, but muggles don't even know its existence. Psychics, then, often subjected to this trope.
Haruka is accused of this with her mind reading abilities, particularly when she was younger, when she was said to be a compulsive liar as she innocently blurt out other people's inner thoughts and secrets. This is not helped by the fact Japanese do have a tradition of lying to conform with social norms, and her case of Power Incontinence makes it her for her to distinguish between speech and thoughts.
Yuriko's mother Chizuru was a clairvoyant, but was Driven to Suicide after falsely accused to have faked her powers. Even now, most people see her powers as a fake, with the exception of Yuriko herself and her Childhood Friend Dai'chi.
In Lucky Star, nobody—not even his daughter Konata—believes that Soujirou is actually a hardworking writer who can write wholesome, non-otaku-related topics, has quite a bit of book smarts, has had a relationship with Kanata that was far beyond lolicon, so on and so forth.
Jor-El in nearly every version of Superman's origin. The classic story is that he tells the Kryptonian High Council (or something like that) that Krypton is doomed and they must evacuate, but nobody believes him, so he's forced to send his infant son to Earth in a small rocket.
Averted in the origin of Superboy Prime from D.C. Comics Presents #87, where the Jor-El of the Prime Universe tells colleagues that Krypton is doomed, and everyone believes him, but bureaucracy gets in the way.
The reason no-one believed him in the DCA version was because they relied too much on someone else who they shouldn't have: Brainiac. The computer knew Jor-El was right, but told them a conflicting story, in effect making Krypton the first victim of his mad plan to absorb all the knowledge in creation and then destroy it. (To make it even more dramatic, Bainiac told the council to order Jor-El arrested, but he managed to activate the controls to Kal-El's rocket right before they could; by then, it really didn't matter what they did.)
John Byrne had fun with this during his run. A computer programmer working for Lex Luthor ran extensive data on both Superman and Clark Kent into the system, in order to find a perceived connection between them. When the computer responds, "Clark Kent Is Superman", Lex promptly fires the programmer, refusing to believe that someone with Superman's powers would be satisfied with a "normal" life.
The first volume of Runaways has the superpowered main characters struggling with the fact that no one will believe that their parents are supervillains, resulting in them having to bring them down personally. Conversely, after the Pride are dead, their activities exposed, still few are willing to trust the Runaways, because of who their parents were. In this case it was somewhat subverted by the fact that the characters' parents essentially owned the police and had their fingers in the pies of every major organization, illicit or non, on the West Coast.
Tim Drake finds himself in this situation during "Red Robin" while he is trying to prove that Bruce Wayne is not dead.
In a Swamp Thing storyline where the title character is believed dead, Adam Strange shows up to tell Swampy's girlfriend that he's still alive and is trying to get home to her. She's incredibly relieved... until Adam starts helpfully explaining how he met him on an alien planet that he travels to by "zeta beam", at which point she shuts the door in his face.
In Route 666, the main character is named Cassandra (usually called "Cassie") and suddenly starts seeing a world of ghosts and horrific monsters preying upon humanity. No one else can see this, and so, in her struggles against them, she is also pursued by the police as a psychopathic killer.
Extremely minor character Harvey Who was portrayed as this. A member of the Royal Secret Service, he warned King Max Acorn over not trusting certain characters, including the original Robotnik. However, Max ignored those warnings as he had trusted the mystical Source of All for his guidance. Years later, when Max's son Elias had lost the throne, Harvey decided to help him as he realized he was in a better position to be king than his father ever was because he never used the Source.
Another example is with Sonic himself; even after hearing that Eggman was planning to use a super-weapon that would destroy both the Freedom Fighters' camp and half of the Eggdome in an effort to get rid of him, Sonic brushed off Shadow and Rouge's assertions that Eggman was going crazy until he witnessed Eggman's Villainous Breakdown firsthand.
In Safe Havens, at one point a school photographer snagged a photo of Remora's mermaid transformation, but when he presented it to the school principal she simply denounced it as a photomanip, as Samantha had already shown her several photomanips in advance. Samantha later apologized to him, telling him she had to do it to protect Remora's secret.
In a Tempest strip, when Tempest awakes in an interrogation room, he quickly and clearly tells the questioner that Deathfist and his daughter have broken out of prison and are on their way to Times Square to punch a hole in the space-time continuum. When the lie detector says he's telling the complete truth, the interrogator jumps to the conclusion that he's figured out how to fool it.
Inverted in a running gag throughout Dungeon Keeper Ami, Mercury's repeated attempts to explain that she is NOT a depraved rapist- despite this, the fact that all the stories regarding her exploits in battle are, in fact, true, sabotages her -the rumor mill never lets her catch a break.
This is the basic premise of The Boy Who Cried Yuri, with Shinji on the receiving end. When he tries to alert Misato, she instantly dismisses him — even though she should know very well that he's too much of a coward to make this up. Asuka even lampshades it.
Rei: Asuka, do you think it is wise to do this now? Shinji may come in at any time. Asuka: No, Misato was talking to him. He's probably gotta go apologize to Fuyutsuki for screwing the test up. Rei: Do you think he suspects something? Asuka:I doubt it. Even if he does, people will think he's just fantasizing like he always does. The little pervert. (unknown to them, Shinji's already hiding in the room with a tape recorder)
In Kyon Big Damn Hero, Kyon's sister had tried to tell her parents and friends that her brother is a hero and has real adventures but nobody believes her. This is in part because her brother, knowing she can't keep a secret, tells her enough to know but not enough for her to be believed if she tells someone else.
Lampshaded in the Harry Potter fic When In Doubt Obliviate. After Gilderoy Lockhart complained that Sirius believed that Lockhart had erased his memory before taking him to St. Mungo's that fateful Halloween night, Harry commented that it was the truth.
Lockhart: "That just makes it worse. Still, at least no one else seems to believe it." Harry: "I think it's the way he's phrasing it, really. It makes him sound like it's just a conspiracy theory." Lockhart: "I've never tried the whole Cassandra Truth but it's really working for me."
In Harry Potter and the Descent Into Darkness, a Dark!Harry fic, when picking Harry's "treasure" for the Second Task of the Tri-Wizard Tournament the cup comes up blank when picking a hostage for Harry to save. Everyone assumes the cup is malfunctioning. No one considers that maybe there's no one at Hogwarts that Harry gives a damn about anymore. Also in Divination class Ron scryed that Harry is a manipulativeliar and a murderer but immediately dismisses it as having misread the results.
In the Death NoteSlash FicFever Dreams when Light goes to the media, L manipulates the media in order to suppress Light's story: painting his "Kira experience" and claims of having met the real L in the same light as someone claiming to have had a demonic possession and an Elvis sighting so that no one will ever believe him. There's also the instance when Light is cornered and L has all but proved that he is Kira, Light counters with the argument that if he really was Kira then why were they all still alive and why would he allow himself to be trapped so easily? Aizawa suggests that Kira might just be "a Fool for Love" but L immediately dismisses that idea as ridiculous — Kira would never fall in love with L!
In Ice Age 2, Sid is kidnapped in his sleep by a tribe of mini-sloths who wish to sacrifice him to prevent the coming flood. When he stumbles back into camp the next morning, no one believes his story, insisting that he was just sleepwalking and dreamed the whole thing.
Woody from all three Toy Story films. The first movie he was trying to convince the other toys that Buzz was still alive and he didn't kill him.note He did try to cause him harm, though.The second one he insisted to Jessie and Stinky Pete that Andy didn't break him intentionally. And in the third one, he had difficulty telling the other toys that Andy really wanted to put them in the attic and not in the garbage.
In An American Tail: Fievel Goes West, no one will believe Fievel after he warns them about Cat R. Waul's evil plan to eat all of the mice that he convinced to move west, which Fievel overheard while snooping.
The Land Before Time has Cera try to tell the others that Sharptooth isn't dead. Littlefoot convinced them all otherwise until witnessing Sharptooth again try to eat them.
Snow White and the Seven Dwarfs has an odd variation, where the villain notices the truth herself but is too overconfident to accept it. After indulging in typical Nothing Can Stop Us NowEvil Gloating, the Queen suddenly stops mid-Evil Laugh to ponder, "But wait! There may be an antidote! Nothing must be overlooked!" Then she checks her book, and realizes there is one, but quickly dismisses it, saying, ("Love's first kiss, bah! No fear of that! The Dwarfs will think she's DEAD! She'll be Buried Alive!") As we all know, it didn't turn out that way at all, and this flaw in her plan is exactly what saved Snow White.
In Mulan, when the Huns emerge from the snow, Mulan is the only one who sees it. She returns to the city to inform Shang of this, but he doesn't believe her because she had earlier lied and posed as a soldier. The ordinary folk refuse to listen because she's a woman. In a twist of fate, Shan Yu and his army show up at that exact moment and take the Emperor hostage right in front of everybody.
The Iron Giant toys with this. Earlier on in the movie, Mansley is trying to convince a general that there is a giant metal robot out there, and isn't taken seriously when he does. He was right about that part. However, he was also wrong about the nature of the robot... it was much gentler than he was making it out to be. Eventually, this gets switched around, and the ones trying to convince the army that the giant is gentle are the ones telling a Cassandra Truth.
Happens to Mater in Cars 2. Due to his reputation as a prevaricator of fanciful stories (established in the "Mater's Tall Tales" shorts), none of his friends believe him when he tells about his experiences in international espionage.
Mr. Tweedy in Chicken Run notices early on in the film that the chickens are plotting something and insists on investigating, but his wife, Big Bad Mrs. Tweedy, will have none of it and forces him to think it's all in his head. Naturally, the chickens are left free to organize a revolt, thoroughly humiliate Mrs. Tweedy, and escape.
In Recess: School's Out, the police laugh off and outright mock T.J.'s attempts to tell them that an evil mastermind has taken up residence in the school now that it has been abandoned for the summer. They do this even when T.J.'s friends back him up, and when Ms. Finster tells them that something's going on at the school. The fact that they weren't even willing to believe Finster, a teacher at the same school and thus theoretically a better source than kids also gives them shades of Bad Cop/Incompetent Cop.
Osmosis Jones infiltrates the villain Thrax's organization and learns his entire plan — but because he's a screw-up, nobody believes his warnings. Thrax even points this out, and has a laugh over it.
In Epic MK doesn't believe her father's studies in that there are Leafmen who live in the forest. At least until she gets shrunken down to size to see them for herself.
Films — Live-Action
Almost every live-action Disney film ever.
Jack Sparrow even lampshades this in Curse of the Black Pearl when he tells the two guards exactly why he wants to get onto the ship in Port Royal. He trusts that they will disbelieve him because the truth seems very outlandish and sneaks by them while they're arguing over whether he is or is not lying.
In Dead Man's Chest, Norrington is surprised to learn that Jack was telling the truth about Davy Jones' heart. Jack states that he tells the truth quite a lot, yet people are often surprised. Then Will points out that it's because for all the truth he tells, he still lies a lot. Jack then admits that virtually everything he's told Elizabeth up to that point had been a lie.
The song, "I Saw a Dragon" from Petes Dragon is nothing but this trope.
Expanded Universe material implies that no one really believed Kevin Flynn either. Then, he goes missing, and no one thinks to check the arcade for hidden doors...
The 1994 war film Forrest Gump uses this when Forrest's revelation that he's the owner of the wildly successful Bubba Gump Shrimp Company sends one listener off in unbelieving hysterics. The old woman was unbelieving at first, until he shows her a picture of him and Lieutenant Dan on the cover of Fortune.
A 1980's Disney kid's ghost film "Mr. Boogedy" used this trope in the first film ("Kids, ghosts just don't exist, you're imagining things"), but reached facepalm dimensions in the sequel ("Kids, we sealed the ghosts in the 9 pits of Hades, they can't be back, you're imagining things")
In Home Alone 3, the cops don't believe Alex's claims that burglars are breaking into neighborhood houses. Somewhat justified in that the cops came in three times. It's just that the industrial spies breaking in to houses were pretty good at running away and leaving no traces.
Nobody, not even her husband and therapist, believed Kate's accusations of sweet seemingly nine-year-old Russian Orphan Esther actually being a murderous psychopath.
The Good Son revolves around this trope, with the protagonist attempting in vain to warn his family of the homicidal nature of his cousin. The movie was loosely based on the novel The Bad Seed, which also had a Cassandra Truth plot to it.
At the end, Patrick calls his lawyer and leaves a message on his answering machine where he tearfully confesses that he has killed 20 or so people, including Paul Allen (whose murder is the most important part of the plot). A few days later he sees his lawyer in a restaurant to go speak to him, and is horrified to find that he doesn't believe him, taking it all to be a strange joke.
In a club, a woman asks him what he does, and he replies "Murders and executions". But it's loud and she's not really listening, so she thinks he said "Mergers and acquisitions".
In fact he confesses everything to lots of people throughout the movie, but everyone's too obsessed with their '80s consumerism to notice. Or, it's all in Patrick's mind.
Patrick Bateman: I like to dissect girls. Did you know I'm utterly insane?
The ending of the original Invasion of the Body Snatchers. "THEY'RE ALREADY HERE!! YOU'RE NEXT!!" Actually, come to think of it, all the Body Snatchers movies.
Dr. Ian Malcolm in the first two Jurassic Park movies, but the second in particular; the only character present who experienced what could go wrong when humans and dinosaurs interact, his warnings only seem to be finally taken seriously when the two tyrannosaurs attack the camp, much to his irritation and, well, too late. No amount of Cassandra Truth stops Malcolm from remaining a Jerkass.
In Ghostbusters II, the attempts of the Ghostbusters to warn the mayor that a demonically possessed painting is plotting to destroy the city at 12:00 AM New Year's Day sees them institutionalized, which given how they were right about the events of the first movie, may seem a little harsh (although it was partly due to the machinations of the mayor's scheming aide). In a minor subversion, Peter — who is Genre Savvy enough to see that his colleagues' attempts to struggle against their captors whilst ranting about demonic paintings and the end of the world just makes them look even crazier — merely goes along with it in a calm and reasonable fashion until someone wises up and lets them go.
Peter Venkman: Don't look at me. I think these people are completely nuts.
A common theme in the Final Destination series. Frequently, the initial visions of the hero are only believed by a small number of people. The hero will then try to warn people about death's machinations but will be ignored.
In Grosse Pointe Blank, Martin Blank tells everyone at his class reunion up front that he's an assassin, and everyone assumes he's joking. That is, until he is found having killed another hitman using only a pen.
His girlfriend's father: Good for you, son, it's a growth industry.
In Nighthawks a handsome man picks up a stewardess and goes home with her. She asks him what he does as his profession, and he tells her the truth. "I'm an international terrorist wanted in 19 countries." "Well, maybe someday you'll quit the jokes and tell me what you do for a living."
In The Terminator, the psychologist doesn't believe Reese's story about the future and deems him a paranoid schizophrenic.
Sarah Connor started out Terminator 2 in an institution for largely the same reasons after being caught trying to blow up a Cyberdyne facility, although admittedly she didhave actual issues by that point. In one cut of the film, we see the therapist carted off in a straitjacket and ranting madly after witnessing proof of Sarah's "delusions" come after her.
In T3 he has a rant about seeing impossible things indicating he no longer even believes his own memories, then freaks upon seeing the Terminator validating his own memories of events.
Referenced by Mike in Eight Legged Freaks. After escaping the giant mutant spiders' lair and coming across the town sheriff, he is reluctant to tell his story. This is with physical evidence of a giant spider leg that he managed to take with him. After much prodding, he eventually provides a long-winded, detailed explanation of the trope along with what he saw. To his annoyance, he predictably isn't believed.
David figures out the aliens have embedded their countdown to destroying humanity in the global satellite network. His coworker believes him but is panicky and in no condition to do anything. David's father believes him and takes him all the way to Washington DC, where David's ex-wife blows him off thinking him paranoid. But David is right, and his father wastes no time in reminding people who try to treat David like an idiot. It's really a subversion, because when the president hears him, he believes him immediately.
Russell Casse suffers under this every time he talks about being abducted. He even elicits eyerolls from Major Mitchell when he mentions it at the pilots' briefing before an attack on the HUGE ALIEN SHIP! Even so, it is left ambiguous as to whether he actually was abducted by the aliens or was simply crazy. The eyeroll can be seen as a reflexive reaction from someone who had just learned aliens were really real a couple days before. The way Russell says, "i'M BAAACK!" would imply what happened is real.
Jack: Oh... I had a date tonight, so I had to call and cancel... Cabot: Well, don't be stupid! Tell her where you're going. In fact, tell her who you work for. She'll be impressed. Jack:(to Cathy, over the phone) OK. I work for the CIA, and the Director asked me at the last minute to come with him to Russia with him to do a nuclear arms inspection. Hello? Cathy: That is so lame. (she hangs up; Cabot and the other experienced CIA officers laugh)
In Back to the Future Part III, Doc Brown has decided to return to 1985 from 1885 and goes to tell his girlfriend Clara the truth about the time machine and when he's from. She is enraged and tells him that it would have been better to just say that he doesn't love her.
Also, later Doc tells the locals at the saloon about what life is like in the future, all of it true despite their mockery and disbelief.
Happened in Star Trek IV: The Voyage Home when Admiral Kirk reluctantly explains to Dr. Taylor that the reason he needs her whales is that he's a time traveler from the future. Naturally, she thinks he's nuts. (This is understandable, because Kirk does only a passable job of blending in to the 20th century.) Eventually circumstances force her to turn to him as her last resort, proving once again that if it's crazy but it works, it's not crazy. When the subject is first brought up, it's kind of funny:
Taylor:(after Kirk tries to broach what is obviously an awkward subject) Don't tell me. You're from outer space. Kirk:(oozing charm) No, I'm from Iowa. I just work in outer space.
Star Trek's finest Cassandra Truth occurs in First Contact. Commander Riker and Troi have traveled back to 21st Century Montana and try to convince Zefram Cochrane, inventor of human warp flight and the man responsible for humanity meeting the Vulcans, of the importance of his flight, and why the Borg are trying to stop him.
Cochrane: So... lemme just make sure that I understand you correctly, Commander. A group of cybernetic creatures from the future have traveled back through time to enslave the human race, and you're here to stop them? Riker: That's right. Cochrane: Hot damn! You're heroic! (laughs in Riker's face)
In a word, Darth Vader. He had serious doubts that the Death Star was as invincible and foolproof as everyone thought it was, and while he might have had more success convincing the Rebellion about that, the warning he gave in this scene was ignored by everyone listening (not just Admiral Motti, who Vader infamously had to Force-choke into line to prove a point):
Vader: Don't be too proud of this technological terror you've constructed. The ability to destroy a planet is insignificant next to the power of the Force.
And in the same movie there was the scene during the Battle of Yavin where Moff Tarkin brushed off an advisor's suggestion that the Rebellion's attack actually posed a danger, and refused to consider having his escape craft prepared. He paid for that mistake with his life.
Boris: Who you are working for? Wallace: Blockbuster Video, Des Moines, Iowa. Boris: Who you are working for? Wallace: Blockbuster Video, Des Moines, Iowa. Boris: Damn, they trained him so well.
In The Wedding Date, Debra Messing's character hires a gentleman escort as her date, so that the rest of her family and her ex-fiancé will be jealous. Later, when the groom asks him how he knows so much about women:
Nick: I'm a hooker.
Twelve Monkeys: Not only does nobody believe James Cole when he tells people he's from the future and trying to gather information about a worldwide epidemic, but his time-traveling shenanigans and insane rantings may have very well inspired said epidemic to begin with. Reversed by mid-movie; his therapist convinces him he IS an insane homeless person; by the time he tries to seek mental help and turn himself in, she's found corroborating physical evidence (a WWI-era bullet in his body and a history text showing his face in the trenches.) She has trouble convincing him he's really from the future. Ironically, said therapist has written a book and given speeches on this trope.
Die Hard has one of the most amusing examples of this trope. Protagonist John McClane is attending a Christmas party on the 30th floor of a skyscraper which suddenly gets taken over by terrorists. He pulls the fire alarm in an attempt to get the attention of the authorities, which winds up being canceled by one of the terrorists. He then steals a radio and tries to contact the police that way. Despite audible gunfire in the transmission, the police dispatcher is still unconvinced and informs John he's broadcasting on a restricted channel, prompting the infamous line, "No fucking shit, lady! Do I sound like I'm ordering a pizza?!" It gets even better when she informs him it is illegal to file a false report and he then begs her to send police to arrest him. According to the script, this scene was inspired by a recording of a real 911 call.
Early in Night Watch, a police officer asks Anton if he's been drinking, and Anton says "only blood". The cop doesn't believe him — at least until he starts vomiting it up.
In the Gremlins series, the authorities do not believe that a horde of little monsters that can't be fed after midnight are terrorizing the local movie theatre and sporting good store.
In fact, MAD kind of summed up how this Trope works in their satire of the movie:
Billy: Why won't you guys believe me?
Cop: Because the police never believe the hero until it's too late. Haven't you ever seen old '60's sci-fi movies like The Blob?
Averted in Fight Club, where the Narrator tries to confess his alter ego's crimes, and is believed, only to realize that everyone in the room is in on it.
Played with in True Lies, where Arnold's character has been placed under the effects of a truth serum whilst handcuffed and immobilised. He's half-drunk from the drug, and the doctor administering the truth drug begins to ask questions...
Samir: Now, then, is there anything you'd like to tell me? Harry Tasker: Just that you're going to be dead soon. Samir: Really? Harry Tasker: Yeah. First I'm going to grab you, and use you as a human shield,Then I'm going to kill this guard over here with the Patterson trocar on the table. And then I was thinking about breaking your neck. Samir:(smiling disbelievingly) And how is that going to happen? Harry Tasker: You know my handcuffs? Samir: Yes? Harry Tasker: I picked them. (holds up the handcuffs; events transpire as predicted)
Wait, wait, wait! I have something to tell you. By the time this is over...all of you will be facedown on the floor...and I'll moon-walk out of here. You're not listening to me. First, you're going to help me out of my chair. Then I'll leapfrog over you...before I break his nose. Since my trusty lighter...isn't working, I'll do all this With My Hands Tied behind my back.
One of Walken's last leading roles, The Dead Zone, is also based around this. He is a Cassandra figure.
In Choose Me Keith Carradine's character Mickey keeps telling different outlandish stories about his past to other characters and appears to be a compulsive liar. During the movie, the other characters start cross-checking the various different things he's told them and accuse Mickey of lying to everyone. But at the end of the movie, it's revealed that everything he said to everyone was true.
In Small Soldiers, Christy tells the police about the attacking action figures. The police don't believe her, at which point she realizes that they will come to the house anyway to arrest her for making a prank call. Instead, they hang up.
In The Ladykillers (2004 version) the old lady tries to tell the police that she's found the money from the casino robbery, but the cops don't believe her, instead telling her to donate the money to Bob Jones University.
In the original version she tells the police she's got the money from the robbery but the robbers have mysteriously vanished. The constable, thinking it's another of her crazy dreams tells her she can keep it — much to her surprise and delight.
Poor, poor Andy just doesn't seem to get a break in the Childs Play original trilogy. He tells people that Chuckie's a killer doll and no one believes him until it's too late. His mom goes through the same thing in the 2nd movie before the main detective believes him after Chuckie tries to kill him while driving his car.
Troll 2: Nobody believes Joshua about the goblins until it's too late.
In the Apocalypse film series movie Tribulation, when Tom Canboro's brother-in-law Jason Quincy (Howie Mandel) is being manipulated by future One Nation Earth agents who want to prevent him from spreading the truth before the world is ready for it, neither Tom nor his wife Susan are willing to believe him due to their past dealings with him that lead to their belief that Jason is mentally unstable. However, Tom's sister Eileen somehow senses that the agent has been in Jason's hospital room and is more willing to believe him, though Tom doesn't believe his sister due to her being a born-again Christian who takes the Bible very literally.
Elliot: I'm telling you, the Devil gypped me for a hamburger! Officer: So, do you have a copy of this contract? Elliot: No. I told you, she keeps it in her office. Officer: At this nightclub in Oakland? Elliot: Yes, at a nightclub, and no I can't tell you where it is. Officer: Because you promised the Devil you wouldn't. Elliot: No, because she drove, that's why!
In the Halloween series, Dr. Loomis' entire career in regards to Michael is this. No one ever listens to his warnings about the danger Michael poses to society...even after the dead bodies start piling up.
In Cloak & Dagger, from the beginning no one believes David G. Osborne until near the end when his house has been banged up, two dead bodies have been found, and his eight-year-old friend has been kidnapped. Even then, people don't exactly believe him, but they know something is up.
The police refuse to investigate the two dead bodies in Mystery Team, simply because the main character is an amateur detective.
In The Chronicles of Riddick, Riddick tells the prison guards that he will kill one of them with his teacup. The guard, not believing him, rushes Riddick with a knife, and is promptly impaled on the cup. Riddick then places a tin can key where the cup previously sat. The other guards glance at it, then at Riddick, before hastily leaving.
In Zombi 3 D, we get this little gem from General Morton as his soldiers burn someone infected with the Death One virus:
Dr. Holder's Assistant: Hadn't it ever occurred to you that the ashes, assimilated into the air, could fall back to Earth again? General Morton: That's ridiculous, pure Science Fiction!
In Ghost Rider, Johnny Blaze awkwardly explains to his Old Flame Roxie that he is the devil's bounty hunter, which she believes is merely a ridiculous excuse.
The guard at the French castle in Monty Python and the Holy Grail tells King Arthur that his lord won't join the quest for the Grail because "he's already got one". It seems at first that he's just taunting Arthur, but at the end of the film Arthur learns the location of the Grail, and it's the same castle. It can be inferred from the death of the writer of the location at "Castle of", as well as from the French knight's vague dialogue (he only said his lord's already got one), that the real Grail may be at a different castle.
The Fugitive: Richard Kimble's story of a one-armed breaking into his house and killing his wife. The cops clearly don't believe him from the get-go (in all fairness, in such an investigation, the husband is the prime suspect), and the bizarre detail such as the attacker being a one-armed man all but confirm their (inaccurate) suspicions.
In Ferris Buellers Day Off, the police unaccountably don't believe Jeannie when she calls about Rooney breaking into her house.
This is the entire premise of the 1939 Ginger Rogers comedy Bachelor Mother; at the beginning of the movie, Rogers sees a woman abandoning a baby outside an orphanage. Problem is, everyone from the orphanage to Rogers' boyfriend to her landlady and to her boss thinks the baby really is hers, no matter how much she tries to convince them otherwise.
In The Hobbit, Gandalf and Radagast are convinced that the Necromancer is Sauron or at least someone as dangerous as him. But members of the White Council are either not convinced (Saruman) or powerless to do anything about it (Elrond). Galadriel is the only one who senses something genuinely sinister is happening and puts her faith in Gandalf.
In Midnight Movie Timmy tries to tell the police about the events that occurred in the theater but no one believes him.
In Fright Night, Charley sees his neighbor Jerry grow some fangs and the drink the blood of a helpless lady, so he starts yelling at his mom and friends that Jerry is a vampire without any evidence. Then he calls his police and tells them that the lady was murdered by Jerry, but when the police find problems with Charley's story he immediately falls back to the vampire explanation.
In Now You See Him Now You Dont, after Dexter and his friends discover that A.J. Arno and his flunkies plan to use the stolen invisibility formula to rob the bank and make the money invisible, Dexter and Schuyler try to warn the bank president and the police about this, only to be blown off about it, until the crime has actually been committed.
Inverted in Troy. The priests always give the wrong advice, and are always believed.
The Lady Vanishes has shades of this early in the second act, as Iris tries desperately to convince everyone that Ms. Froy (the eponymous vanished lady) really exists.
Nobody believes the kids the first time they explain what's going on.
At one point the Andalites are sending the majority of their reinforcements to the Anati system instead of Earth, believing the majority of the Yeerk fleet to be there. The kids have inside information that the Anati system situation is an ambush (the asteroid fields are rigged with automated turrets and mines). When they hear this, the Andalite command assumes the kids are lying in an effort to become a priority.
The Boy Who Cried Wolf: After lying so much the villagers don't believe the little boy anymore, even when there's an actual wolf chasing him.
Most books in the Goosebumps series by R.L. Stine, in which the protagonists' supernatural claims are disbelieved by parents and authorities. This is turned around in "The Girl Who Cried Monster"; the girl's parents don't believe that her librarian is a monster, not because they don't think monsters exist, but because she has a habit of making up outlandish stories (in fact, it's her Establishing Character Moment) and because they're monsters, and they thought they'd eliminated all nearby competitors long ago.
In Anne S. Lindbergh's The People in Pineapple Place August's mother does not believe his stories of Pineapple Place, an alley only he can see, filled with families, all of whom only he can see. However, it turns out that his mother is a Reasonable Authority Figure, and comes to believe him once she sees evidence of August's story (a child she (and August) can see, but no one else can, able to get away with considerable mischief, and a security guard, apparently making a fool out of himself in front of a large crowd of people, none of whom (except August) can see the girl he (truthfully) claims to have caught roller-skating in a museum).
“You don’t understand, Professor. Harry Potter’s coming — he’s got a dragon!” "Someone's trying to steal the Philosopher's Stone", "Sirius Black is innocent", "Voldemort has returned", "Draco is trying to KILL people"...
Sybill (great-granddaughter of famous Seer Cassandra) Trelawney is regarded as a fraud by her colleagues and some of her students, but the mindful reader will notice that almost everything she "predicts" does happen, just not in the way she says it will.
An interesting twist on the classic trope is that anytime Ron makes a snarky comment, half the time he's right. In Philosopher's Stone: "I'll kill Fred, he was going on about wrestling a troll." Guess what they're doing a chapter or two later? In Chamber of Secrets: "Maybe he murdered Myrtle, that would have done everyone a favor." And the previous victim of the Heir of Slytherin is... Less obvious examples in Prisoner of Azkaban: "She's still acting like Scabbers has gone on vacation, or something." Surprise, surprise, Scabbers wasn't dead after all, just hanging out in Hagrid's hut. "What would [Hermione's Boggart] have been for you? A piece of homework that only got nine out of ten?" Lo and behold, Hermione's boggart is McGonagall telling her she failed everything. But overall, perhaps not so much them actively not believing Ron, as they're just not paying attention.
The Dresden Files has a condition called Cassandra's Tears, resulting in a person having somewhat reliable visions of the future, which no one believes. If someone does believe, the condition may be cured — but it's easily faked and a common confidence scam among the magical community. Which probably contributes to the fact that no one believes the predictions. More medically, genuine cases are also easy to mistake for garden-variety seizures, so people not in on The Masquerade, or people in on it but not suspecting the condition, could end up trying to medicate the wrong problem.
Cassandra herself shows up in one scene of the Everworld series, displaying just how thorough her curse is. Despite knowing all about her story, and having lived in a world where every myth and legend from all cultures throughout history coexist, the heroes still refuse to believe a word she says, including the statement that she is Cassandra, thanks to the curse's influence. Just to rub salt in the wound, they actually consider making a concerted effort to believe her, on the off chance she is Cassandra, before forgetting what she actually said and then deciding ignore it.
Part of its premise is a deliberate subversion of the trope with author Richard Adams wondering "What if the Cassandra character was believed?" So in this book, the Waif Prophet, Fiver, is taken seriously by his brother and a select few who escape a doomed warren. There is some doubt when they enter the seemingly idyllic Cowslip's warren that Fiver warns not to enter while the gang ignores him. However, when the place's horrific secret is revealed, the company then accepts Fiver's counsel without question, such as when the group encounters a electricity transmission tower and Fiver firmly tells them that it is of no danger to them.
** Not all the rabbits who joined Fiver in the first place necessarily believed him (although Hazel did); they were dissatisfied with their life in the warren and thought they'd have it better elsewhere. It's only after he is proven right, both about their home warren and about Cowslip, that that all really start believing him.
Not just that, an El-ahrairah short story in the book relies on El-ahrairah constructing a Cassandra out of a suspected spy so that he would lose his credibility and be ordered to leave the warren.
Chorus: Why do you cry out thus, unless at some vision of horror? Cassandra: The house reeks of death and dripping blood. Chorus: 'Tis but the odor of the altar sacrifice. Cassandra: The stench is like a breath from the tomb.
James Thurber's The Catbird Seat is about a man who plots to get rid of an incredibly obnoxious woman who works at his office; she's driven away most of his colleagues and is about to talk his superior into cutting out the man's department. The man, a clean-living, sober type who wouldn't hurt a fly, visits her apartment one night, at which point he drinks whiskey, smokes a cigar and discusses his plan to kill his boss using very harsh language. The next day, the woman tries to warn their boss of the man's plan... and is fired when the boss thinks she's having a breakdown.
This sounds very similar to what happens in his short story The Unicorn in the Garden.
Children's book Voyage of the Basset (the movie Voyage of the Unicorn is based on it) has a mythology-loving college professor whose daughter, Cassandra, is specifically named after this character. Cassandra somewhat lives up to her name when her warnings to her father about what not to do and trouble that could be caused are completely brushed aside, resulting in him getting pissed off and acting nasty to her. He later apologizes when she turns out to be right. (In the movie, he has a nicer personality and the "ignored warnings" thing is avoided.)
A short story started with a boy not being able to sleep because he had a fly in his ear. Then all four siblings got up and had a midnight party, playing make believe games so that when the toddler told the parents the next morning they assumed it was a dream, until he mentioned the fly in his brother's ear.
Coraline calls the police to tell them that her parents are missing — and she thinks they were taken by the creepy lady with buttons for eyes who lives in the Alternate Universe connected to her house. The police tell her to go back to bed, sweetie.
A major part of the plot in the Warrior Cats book Dark River: when a crisis on RiverClan territory forces them out of their camp, the other Clans all start preparing for invasion, since they believe that RiverClan will now try to take some new territory. Hollypaw is seemingly the only cat on the lake that notices that all these fears are founded on nothing but paranoia, and that by preparing for a battle, everyone is making it that much more likely to happen. Naturally, nobody listens to her when she says they should try to help RiverClan with their problem, or at least get more information about it before jumping to conclusions, because she's just an apprentice and they are all "more experienced".
Night's Dawn trilogy by Peter F. Hamilton. Joshua Calvert always tells a different story over how his father damaged his spaceship The Lady MacBeth, usually involving some form of selfless heroics. Eventually his girlfriend asks for the real story, and is given one involving terrorists and mysterious alien technology. Naturally she doesn't believe a word of it, much to Calvert's annoyance, but a short story by Peter F. Hamilton in another book reveals that he is in fact telling the complete truth.
In Pseudonymous Bosch's The Name Of This Book Is Secret, and its sequels, the main character is named after the character from Greek legend and is often not believed by adults. A fairly detailed description of the original Cassandra character is given in the first book.
In the short story collection Far North & Other Dark Tales, by Sara Maitland, the mythological story of Cassandra is retold as being the result of a Apollo severing her corpus callosum as revenge for her withholding the sex she had promised in exchange for the gift of prophesy. She can see the future, but because of her brain damage cannot articulate clearly enough to be understood.
Fanny Price in Mansfield Park tries to warn Edmund that Henry Crawford is constantly flirting with his sister. Who is engaged to someone else. This does not end well.
Miss Bates in Emma is also usually right, but her Motor Mouth tendency causes people to tune her out.
Charlotte Collins in Pride and Prejudice is also frequently right. Elizabeth assumes she's just jealous.
Elizabeth herself, when she tries to warn her father that allowing her sister Lydia to go to Brighton with the regiment will end in disaster. It does. He magnanimously tells her that "I bear you no ill will for being justified in your advice to me."
In Stieg Larsson's The Millennium Trilogy, Lisbeth repeatedly told authorities as a child about her father's abuse of her mother, but no one did anything and she wound up being institutionalised after attempting to take matters into her own hands. There turned out to be a giant government conspiracy responsible for covering up her father's crimes, so this isn't entirely a straight example of the trope. It's also largely responsible for turning her into the person she is today.
Played for Laughs at the end of the Dale Brown novel Flight of the Old Dog, where Patrick McLanahan casually tells his mother that he had just come back from bombing Russia. Mrs. McLanahan doesn't believe him. Also used seriously in Plan of Attack, where no one outside of the Air Battle Force believes that a Russian attack is coming, as well as in Edge of Battle where no one believes just how dangerous Comandante Veracruz's plan really is.
In Jill Paton Walsh's A Presumption of Death, retired dentist Mrs. Spright is paranoid and senile so nobody pays attention when she claims that there are Nazi spies in Paggleham. It turns out that she's right.
In Glen Duncans I, Lucifer, the fallen angel Lucifer casually tells people exactly who is, despite being in a mortal body, only to be seen as joking or eccentric. He even continues being himself when in talks to create a movie on his life story.
Jared in The Field Guide, the first installment of The Spiderwick Chronicles, tries to tell his family that faeries are causing all the mischief that he is being blamed for...but, since he's nine and has been acting mischievously as of late anyway, no one believes him.
In the Honor Harrington books, the few Solarians that recognise how far behind the times their Navy is are often casually dismissed as alarmists and defeatists.
In Flyte, only Beetle and Nicko trust Septimus when he tells them that Jenna has been kidnapped by Simon Heap.
Jenna tries in vain to warn Septimus of the upcoming Darke Domaine in Darke.
Kill time or die trying: Brad spends his entire first day at university trying to figure out where to go. The only reliable directions he's given come from a pair of stoners, who he ignores.
The Changeover: Laura attempts to inform her muggle mother as to what her brother Jacko's condition truly is, to no avail. Subverted soon after with romantic lead Sorry, who doesn't believe her at first but then drops by and confirms Jacko's condition himself.
Subverted in "Police Operation" by H. Beam Piper. The Paratime Police are shown to actively take action to make true accounts of Paratime doings seem false. Flying saucers, their existence, and the relevant 'smothering out' technique are particularly discussed.
Dave Pelzer wrote A Child Called It about his experiences as the victim of the third-worst case of child abuse in Californian history. The evidence was clear across his body on a daily basis, up to broken bones (and worse!), and yet the school officials took several years to conclude it was bad enough to intervene. Worse because the couple of times he tried to tell, early on, they'd just call his mother, and send him back to her, and she'd abuse him even worse - so he stopped trying to tell anyone at all.
In the Trylle Trilogy, Wendy's mother stabbed her at the age of 6, claiming that she was a changeling switched at birth with her son. Wendy's family is horrified, and her mother is put into a mental hospital. Wendy eventually finds out that she is a changeling troll and her mother's real son is being raised by Wendy's biological mother Elora.
Galaxy of Fear: Eaten Alive, a ship called the Misanthrope crashes on an uncharted world that the natives call D'vouran. The twenty surviving crew find an abandoned lab that they hole up in, not trusting the natives, and find that one by one anyone who leaves disappears. The scientists got the ground to come to life and eat people other than the natives. The captain, Kevreb Bebo, is able to leave thanks to a trinket that keeps him safe; when other people start landing on D'vouran he frantically tries to warn them, but isn't believed. There's never any evidence; when he takes the last of the crew with him to help convince people, she disappears too. Gradually, a sympathetic Tash Arranda does decide to hear him out, because she too is not believed when she talks about the bad feeling she has about the place.
The Mortal Instruments: In City Of Glass Jace's outright dislike and suspicion of Sebastian raises a lot of eyebrows despite the fact that he was right all along.
The Malloreon: In Demon Lord of Karanda Polgara pronounces a curse on a grolim:
Polgara: You are now invincible. No one can kill you—no man, no demon—not even you yourself. BUT no one will ever again believe a single word that you say. You will be faced with constant ridicule and derision all the days of your life and you will be driven out wherever you go, to wander the world a sa rootless vagabond.
Grolim: Who are you, woman? And what power do you have to pronounce so terrible a curse? Polgara: I am Polgara. You may have heard of me. Sadi: Do you think it was wise to reveal your identity, my lady? Polgara: There's no danger, Sadi. He can shout my name from every foortop, but no one will believe him.
Not strictly a Cassandra, in that the grolim doesn't have perfect vision, but he does know at least one true and potentially valuable thing that he'd probably like to share.
Lolita. After emptying a couple of pistol magazines into fellow paedophile Claire Quilty, Humbert discovers some Upper Class Twits have turned up for a dinner party at his house. He confesses to killing the man, but they just joke that someone should have done it a long time ago. It doesn't help that a dying Quilty then staggers into the room.
Government agents capture Lex who has trashed them effortlessly when possessed by Zod. He admits that an alien warlord has inhibited him and granted him with godlike powers, but naturally they don't believe him.
Actually, whenever someone talks about "little green men" from space. Pete "reveals" Clark's secret twice, once to Chloe and the second time to a random crowd, this way.
G'Kar of Babylon 5 has been described as JMS's Cassandra; at various points, he predicts what will happen, but no one believes him, mostly because they don't want to. For example, he tries to warn other races that the Centauri, having conquered the Narn, will turn their attention to others... which they promptly do. It was later revealed that both Delenn and Kosh knew some of his rantings were true but couldn't act in case it showed their hand too early. G'Kar calling Delenn on it when he finally found out was awesome.
The focus of "iTwins". Freddie doesn't believe that Sam really has a twin sister after being pranked twice and not having seen Sam and Melanie at the same time. Also, Carly doesn't believe Spencer's accusations of the multitudes of abuse he got from Chuck.
In "iSpace Out", a little girl finds her way into the apartment, but when Spencer tried to show her to a police officer, she'd hidden somewhere.
In the first episode, Claire announces at the dinner table, "I walked through fire today, and I didn't get burned." However, her mother thinks she's just being metaphorical and profound. Although to be fair, her brother was fairly suspicious and her mother isn't the sharpest anymore since the Haitian has been repeatedly wiping her memory which has resulted in the equivalent of punching her brain.
Angela Petrelli explicitly references the Trope Namer when she talks about her ability in the episode "Into Asylum". She also states that trying to work around this skepticism is what turned her into the Manipulative Bitch that we all know and love today.
Chief: How did you figure that out? Boomer: I'm a Cylon. Chief: That's not funny!
They later built a Bizarro Episode around this trope, with Helo trying to unravel a conspiracy that's just so stupid and outlandish it can't be true. It turns out to really be true and everyone walks away with egg on their face (even Helo) because of how stupid they all acted during the event. And then Ron Moore said: "Let Us Never Speak of This Again."
River really is a seer, but since she's also a paranoid schizophrenic, people generally don't listen to her until late in the series.
Inverted in the Big Damn Movie. While the Cassandra of myth went insane because nobody believed her, River, who started out insane, regains her sanity after the crew finally believe her.
Debatable example but Jayne's opinions are often disregarded because he is, quite simply, an asshat but he also seems to have a point more often than not (finishing the job for Niska, Tams being trouble, bringing grenades on the bank job).
This is half the plot of First Wave. Our heroes try to prevent and reveal the first stages of an alien invasion. No one but a small collection of conspiracy nuts believe them.
Olive: Why'd you fake your death? Is this an insurance scam? Are you and the pie maker in some kind of cahoots together? Chuck: I died. And he brought me back to life. Cahoots enough for you? Olive: If you don't want to tell me, just say so.
Lately, Hank of Royal Pains. No one believes that his father, Eddie R., is as toxic as he claims. Not even Evan. Especially not Evan.
Throughout the episode "Point of No Return", Martin Lloyd (who's portrayed as a strawman believer in conspiracy theories) tries to convince O'Neill that he's an alien with suppressed memory, and succeeds only after they discover the escape pod in which he landed. In "Wormhole X-Treme!", the situation is reversed: now it's O'Neill trying to convince Martin that he's an alien and subconsciously based the Show Within a Show on the real Stargate program. Martin thinks it's a practical joke and writes down O'Neill's explanations as plot ideas for his show.
However, most of the time, the show doesn't succumb to this trope. It's not unusual for a character to experience something highly unusual, like seeing the future, and have everyone believe them. When you've seen as much weird stuff as the SGC has, you become more willing to believe in the unusual. In fact, on several occasions, one character has told the others about a crazy theory/experience... and is met with short-lived skepticism. Short-lived, because it becomes an excuse to list off the other crazy things they've been through.
Although one of the earlier instances of this was at the end of the first season, when Daniel Jackson goes into an alternate universe and sees the Goa'uld attack Earth. He claims that he has the coordinates of where the Goa'uld will attack from, but no one takes him seriously until later on.
Samantha Carter: Daniel, it's not that we don't believe you. Daniel Jackson: So you do? Jack O'Neill: No. It's just that... we don't believe you.
Jack Bauer on 24 repeatedly takes the role of the Cassandra, which is frankly bizarre when you consider his extensive field experience and the fact that he's almost always right. Though, to be fair the high rate of turnover on the show means that about the only person alive at this point who knows him well enough to trust him is the one who does, Chloe O'Brien. A lot of the field agents will believe him as well, it's just the higher ups that never do. There's actually a saying for this: "If everybody did what Jack Bauer told them to do, the show would have to be called 12."
In fact, this trope gets played with in the final episodes. When Jack goes off on his own after the Russian masterminds behind the murder of President Hassan, Chloe for once doesn't believe his claim that they're behind it and refuses to work with him, due to recent events including the death of a woman he'd just started to become lovers with, and she feels he's not thinking straight because of it. Unfortunately, in this case, Chloe's also right: Jack isn't thinking straight. He wants to kill them all in revenge rather than just exposing them (well, he does kind of, but rather as just a back-up plan in case he dies in action as some type of final "screw you"). Did I mention said masterminds are also members of the Russian Government and killing them would cause an international crisis?
Done in Sister Sister: Tamera promises her dad to tell the truth for the day, then sees his girlfriend with another man at a movie theater. When she tells him, he's so disappointed that she broke her promise... until he catches her with the other guy when they go out to dinner.
Virtually everything the immortal John says to his coworkers in New Amsterdam.
The Xindi story arc features a few of these. Most notably, Daniels has to bring Archer to the future to see the truth of the Xindi's misguided attempts to destroy humanity. When Archer tried to explain to the Xindi that not only was humanity not going to attack them, they were actually going to join forces at some point in the future and defeat a common foe, the Xindi council almost has him executed for his "blasphemy". Admittedly the Xindi did see this foe as gods/angels at the time and they had a different story of future events.
In the follow-up episode to the events of Star Trek: First Contact, Archer remembers that Zefram Cochrane related a simplified version of the events of the film. At the time, people had dismissed it as one of his drunken flights of fancy. He gives it more attention now that he's actually dealing with the Borg.
Subverted in the episode "In The Cards". Jake and Nog's Chain of Deals has attracted the attention of the bad guys, who refuse to believe they're going to all that effort to get a baseball card for Jake's dad. Jake therefore decides to take Refuge in Audacity, and instead claims they need the card for a secret Starfleet mission; Willie Mays is a time traveller, and they have to find out what he was doing in the past. After a moment of uncertainty Weyoun says "I believe you. That is, I believe your first story."
In the same episode, Jake and Nog's attempts to tell station personnel that something weird is going on (without mentioning the card) consistently fail when they get to Dr Elias Giger and his "cellular regeneration and entertainment device" (understandably, since the implication of the episode was that this was Technobabble by Star Trek standards). Weyoun turns out to believe that as well.
Dick, guilt-ridden, finally decides he must tell Mary everything about himself to have an honest relationship. He tells her who he is, where he's from, why he's on Earth, and who sent him. Being that they are at a Sci-Fi convention at the time, she merely replies that she is, in fact, an alien sex queen.
Another 3rd Rock example: when Dick is facing an IRS audit he finally breaks down and confesses to being an alien, to which the tax guy simply mutters, "Sorry, I've heard that one before."
And a third example involving Dick, this time while he's sick with a cold and, believing that he's dying, confesses to Mary, who thinks he's just being delirious.
Another example by Dick: when Dick dreams for the first time, he thinks he's gone mad and goes to see a psychologist. He ends up confessing his status as an alien to the psychologist, who thinks this is evidence Dick is experiencing major delusions.
Arrested Development: Michael and George Michael learn An Aesop about being honest with each other after Michael misinterprets his son's behavior. With his father repeatedly telling him that he can share anything with him, George Michael blurts out that he is in love with his cousin Maeby. The mood becomes deathly silent, until Michael realises it was a "joke" on him.
Cassandra Spender in The X-Files, with her stories of alien abduction and alien intentions that were deluded and then real. Well, for that matter, Mulder, with his stories of aliens and government conspiracies.
In Carnivŕle, when Libby finally tells her mom the truth about why she and Jonesy were gone all day, that is, that they were kidnapped by some men who tarred and feathered Jonesy and left them in the middle of nowhere, until Ben happened to show up and heal Jonesy, and that Jonesy and Ben went off to find Ben's dad, she doesn't believe a word of it, even though I can't think of any reason why anyone would possibly make that story up.
She told her mom the story (which was true) because her mom was relentlessly telling her that Jonesy had run off. To shut her mom up, Libby told her the truth.
This happened nearly every week in the early episodes of Monk; the implausibility of Monk's theory about the crime would be met with disbelief by the police captain, and usually everyone else. The show wisely eventually dropped this, with the captain beginning to accept Monk's explanations because he always turns out to be right, even (reluctantly) defending Monk against each week's stand-in skeptic.
Dexter, in the episode "Shrink Wrap". Dexter was already planning to kill his therapist for pushing three of his patients to suicide, so it didn't really matter if the therapist believed him or not.
Dexter: I'm gonna tell you something that I've never told anyone before. Dr. Meridian: Okay. Dexter: I'm a serial killer. Oh God, that feels so amazing to say out loud! Dr. Meridian: Well, you must be letting go, because I've never heard you make a joke before.
In the Power Rangers Lightspeed Rescue episodes where the current Rangers team up with the previous group, the plot starts with a young girl discovering that aliens are secretly kidnapping people in the building her father works at. When trying to tell the genial old secretary on the first floor about it, the woman kindly informs her that monsters don't exist. Despite the fact that they live in an area currently infested by demons that attack weekly in an effort to completely wipe their city off the map so they can recreate their ancient society.
Power Rangers Zeo had a recursive Cassandra Truth, one time when Those Two Guys Bulk and Skull got caught up in an adventure and helped rescue some aliens. None of their friends believed them when they told the story - except the ones that were secretly the Rangers, but when they said so Bulk and Skull assumed they were just humoring them.
In "Raised by Another", Claire tells everyone that someone is attacking her in her sleep and trying to inject something into her pregnant belly. They all dismiss this as vivid dreams of a pregnant woman, only to feel suitably guilty when Ethan (who has indeed been giving her injections) kidnaps Claire and almost kills Charlie.
Another episode had Sayid traveling back in time to the 1970's along with some other characters. He is forcefed a pill forcing him to tell the truth. He does, and everyone thinks there must be something wrong with the pill.
Yet another episode had Hurley finally coming clean to Charlie that he was a multi-millionaire lottery winner. Charlie thinks Hurley's just messing with him.
In the serial Power of the Daleks, no one in the colony, who have come to use the Daleks as servants, will believe the Doctor's warnings that the Daleks are evil.
Pretty much the same thing happens in "Victory Of The Daleks".
In The Myth Makers, Cassandra herself is a character. No one listens to her.
Played for Tears when Donna screams at the people of Pompeii to run to the hills, rather than the beach. No one listens.
In The Listener, Toby has a terrible time getting anyone to listen to the information he learns, mainly because he can't source it without revealing his secret.
MA Dtv, in a parody of Medium. Allison repeatedly tries to warn the District Attorney of an impending homicide.
Allison: A man named Martin Grier is going to kill a woman named Susan Monroe at 466 South 27th street. DA: I don't understand... Who is Susan Monroe? Allison: She came to me in a dream last night. DA: I don't understand... a dream? Allison: ... Yeah... a dream. Every week I have a dream that helps you solve a crime... Every week. DA: I don't understand. Allison, just because you had a dream doesn't mean I can send my men on a wild goose chase. Allison: ... Well, you could send them to 466 South 27th street...
Yuri Aso in Kamen Rider Kiva is always being told Cassandra Truths ("I'm 105 years old.", "Your love interest is actually a homicidal monster who wants to use you to repopulate his race.") but never believes them. You would think a professional monster hunter would be less skeptical. Within the series, it's assumed that any monstery things other than the Fangire are extinct because of the Fangire. Why would a professional vampire hunter think that one of her suitors is a werewolf seeking to use her as a baby factory, that his friends the little shoe shine boy and the tall silent masseuse are a fishman and Frankenstein's Monster respectively?
In Kamen Rider Decade, self-proclaimed prophet Narutaki spends most of the series claiming that the title character is the Destroyer of Worlds and must be stopped. It looks like this trope because Tsukasa/Decade is doing his best to save parallel worlds and is actually connecting them. This isn't helped by the fact that even people like Kazuma Kenzaki say the same thing. It turns out Narutaki was right and wrong — Decade's job is to destroy the multiverse, but Tsukasa's actions in connecting the worlds not only brought them all back but ensured that they would become legends and exist forever.
What really makes this a Mind Screw: In the Grand Finale movie, Narutaki reveals himself as Colonel Zol, which suggests that he was trying to get Decade defeated so Shocker would have an easier time taking over the multiverse.
On The Office (US), Jim hid Andy's cell phone in the ceiling and started calling it so Andy would hear his phone ringing but have no idea where it was. Eventually, Jim said "Maybe it's in the ceiling," to which Andy replied, "Maybe you're in the ceiling!" and continued looking.
On Wizards of Waverly Place, at first, Alex didn't believe Justin when he said that their Aunt Megan was just like her, but after Megan says that she doesn't like hard work, Alex comments, "Oh my gosh, she is just like me". Subverted later in the episode, when Justin rescinds his statement and points out the difference between the two of them: Megan never learned how to apologize or even admit that she was wrong.
On Wonderfalls, inanimate objects with faces talk to Jaye Tyler. When her best friend, Mahandra, asks Jaye what's wrong, Jaye tells her the truth, which prompts Mahandra to tell Jaye that Mahandra is there to listen to Jaye when Jaye wants to tell her what's actually wrong. She also makes some references to the objects when talking to Eric, but he seems to assume that she's just a very strange person using odd metaphors.
On Kyle XY, in one episode, Lori, Amanda, Hillary, and Declan go to a college bar to try and get a DJ for the Prom, and Declan starts a brawl. Later in the episode, when her parents ask her what she did that day, she tells them the truth, only to have it laughed off. Josh also says something along the lines of, "If you wanted it to be believable, you should've left Amanda out of it."
Played heartbreakingly straight in Skins, where Emily's coming out to her parents is assumed to be a sarcastic confession but is actually dead serious.
Emily: I've been making love to a girl... Her name's Naomi. She's rather beautiful. So I was nailing her. (beat) Rob: OK, OK, I get it. Nice one, had me going there! (continues to bust up laughing)
In The 4400, Maia had a vision that Jordan Collier was going to be assassinated. Her mother brought it to Collier, but he didn't believe her. Later seasons had a better track record of believing the psychic kid, eventually fully subverted when one of her visions was finally believed, only to be revealed that she was lying about it so that Collier and the rest of the P+ would let her and their other captives go.
According to a CSI: Miami flashback episode, Horatio was this when he first joined the Miami PD, dealing with lethargic cops who wanted to put the wrong man behind bars because he was the right culprit according to their antiquated methods — but not according to Horatio's observation and desire to try new methods. As if he couldn't be any more of a God-Mode Sue.
A Red Dwarf episode features a computer called Cassandra who can predict the future. However, her predictions aren't always as clear-cut as they seem and she tries to manipulate people by giving false predictions. In an interesting variant, though, she had been abandoned not because no one believed her predictions, but because no one wanted to hear them (because accurate truths about the future were often uncomfortable). She's not a perfect example of a Cassandra however, because her veracity was never really in doubt. However, Rimmer was so determined to believe that the 1st prediction of his death had some kind of Prophecy Twist that he actually managed to cause the twist and have another crewmember die whilst wearing Rimmer's name tagged jacket. He changed his tune, however, when the 2nd prediction of his death involved him having sex with Kochanski. Also, all her manipulations of the Red Dwarf crew came about because she was trying to alter her future and prevent her own death, which the end of the episode showed was impossible: she died due to Lister accidentally causing a chain reaction started by a piece of chewing gum.
During an episode of The Invisible Man, Darien's ex-mentor shows up at his place to catch up and offer him a stake in her heist.
Liz: You went up for life on a third strike rap, it was in all the papers. How'd you get out? Darien: Well... if you must know, I was pardoned by a secret intelligence agency who surgically implanted a gland into my brain to turn me into a super-agent. Liz: ... You don't wanna talk about it. That's cool.
An episode of the original Twilight Zone features a man who travels back in time, right before Abraham Lincoln is shot and killed at Ford's Theatre. He tries to prevent Lincoln's assassination and ends up in jail for acting "drunk" (until he is bailed out by John Wilkes Booth, who believes his story).
"The Time Element", the rarely-seen TZ pilot that aired on the Westinghouse Desilu Playhouse, has a similar plot about a man traveling back to 1941 Honolulu just prior to the Pearl Harbor attack.
The famous "Nightmare at 20,000 Feet" episode. A man on a plane sees a gremlin on the wing of a plane. He tries desperately to warn the crew. They don't listen.
Done hilariously in Merlin when he ran into the throne room, claiming he was a wizard, to protect Gwen who was about to executed. Arthur (who doesn't know about Merlin being a wizard) comes to his rescue, by saying he was in love with Gwen and claiming that there was no way an idiot like Merlin could possibly be a wizard.
He also regularly stumbles upon a Cassandra Truth. He either has no evidence or the evidence disappears.
Kelly in Harper's Island sees John Wakefield, the Ax-CrazyBig Bad, alive. No one else does and they all believe that she's insane. Turns out he's alive and dangerous. It's likely she's one of his first victims because she knows the truth. Kelly does have a habit of insisting that You Have to Believe Me though.
Gordon Walker in Supernatural finds out about how children like Sam are supposed to be part of a demon army and tries repeatedly to convince Dean that Sam is evil and must be killed. And then in the beginning of Season 5 — oops! — it's revealed that Sam is, and has always been destined to be, the vessel for Lucifer. But then in the season 5 finale it's subverted, because, as Bobby had pointed out in the previous episode, if anyone could overcome the effects of Satanic possession, Sam can. Which, thanks in part to both The Power of (Brotherly) Love and to Dean's heroic stubbornness/suicidal co-dependency, Sam does.
An episode of Beyond Belief Fact Or Fiction features a story where a little boy insists that there's a monster in his closet and is tormented mercilessly by his older brother and a pack of bullies because of it. Finally, the boy dares the brother to go stand in the closet with the door closed. The brother does, and, following some terrified screaming, their Mom opens the closet door to find that the brother HAS DISAPPEARED. The really scary thing? The story was listed as "Fact".
One episode of Family Matters had Carl becoming especially angry at Steve Urkel for some reason, and throwing him out of the house. Steve was trying to warn Carl that the lamp he was fixing had a dangerous short circuit in it, and that Carl shouldn't plug it in, but the sneering Carl just ignored him and told him to leave. As Steve heads for the door, Carl plugs in the lamp and is electrocuted, and would likely have died if Steve hadn't come back and given him CPR.
Paige spent a significant amount of time in season 4 insisting that Phoebe's ex-demon boyfriend Cole was in fact still an evil demon. Everyone else insisted that she simply didn't like him, and no one believed her, until he successfully turned Phoebe to the dark side and became The Source Of All Evil, with Phoebe as his evil queen. Needless to say, Paige earns the right to "I told you so."
It is usually in the earlier seasons but Giles and her other friends often do not believe the hunches Buffy gets about upcoming evil events and who is responsible for them. The most notorious example may have been when she told her friend that her new college roommate, Kathy was not human and held up a bag of her clipped toenails as proof. They actually trapped her in a net, tied her to a chair, and tried to warn Cathy. Turned out she was a demon from another dimension. Although it's later revealed Cathy was slowly stealing Buffy's soul, which was causing her to act in a very bizarre manner. The end of the episode even indicates that Buffy just can't stand having roommates.
When Buffy first became the Slayer, she tried to tell her parents, who responded by putting her in a mental institution. She eventually stopped talking about it, and got to go home. Or did she?
It is, however, averted when Oz starts to become a regular character. He sees Buffy slay a vampire, and after briefly summarising the whole vampire/demon situation, Willow says "I know this must be hard to believe", only for Oz to respond "Actually this explains a lot."
In a pretty direct Shout Out to the original myth, one episode features a girl named - that's right - Cassie, who has visions of the future that no one believes. Buffy actively saves Cassie's life twice on the day she predicted she would die, but she ends up falling to the ground dead anyway.
In Wolfblood, Shannon spends a large part of the first season trying to convince people that there's a monster on the moors. At one point, she becomes convinced that Maddy is the beast... which is of course true. Unfortunately for her, everyone else just thinks that Maddy is dating Rhydian and that's why they keep sneaking off.
Dexter, in the episode than asks Alex what's bothering her. He figured she was in some kind of trouble with the mob, or something. Alex finally spills the beans because she's planning to escape and she's worried Division will interrogate or kill him. Nathan believes her story about government conspiracy agents is a diversion to deny what's really bothering her.
In an episode of Seinfeld, George is truthfully attempting to explain away a very strange series of coincidences to an old childhood friend, who is convinced that George is going insane and doesn't believe his (admittedly odd-sounding) explanations.
In Breaking Bad season 3 episode 1, Hank is helping Walt move out. He takes a bag full of money and when he asks Walt what is making the sport bag so heavy, Walt replies: “Half a million in cash.” Hank thinks it's a joke and laughs.
Once Upon a Time: Sure, kiddo. Everyone in this small town is a fairy-tale character with amnesia. Your (adopted) mom hauled you into a shrink and you end up calling the shrink Jiminy Cricket. You're a little messed up in the head...hey, wait. What's your mom doing with those shards of glass and that door in the graveyard...?
Wil in Season 2 of The Amazing Race. He never missed an opportunity to tell his ex-wife Tara that helping out fellow racers Chris & Alex was a bad idea, and they should be concentrating on the race instead of helping another team. Though he was ultimately proven right when Chris & Alex passed them up in the finale, he was portrayed as a villain because of this... that and he was a Jerkass.
In an episode of Frasier Daphne tries to explain that her Greek friend Zena will soon be arriving on her (the friend's) mother's ship, but the other person thinks she's talking about Xena arriving on an alien mothership.
Person of Interest: Root's Start of Darkness came when she witnessed her best friend get kidnapped (And was later murdered and secretly buried) and nobody believed her when she reported what she saw to the police.
In an episode of Lois and Clark, the recurring villain Tempus (a bored time-traveler from the idyllic future) travels to a parallel world, followed by the titular characters. After beating him, he has a press conference where he publicly outs Superman's identity... Cue Lois and Clark appearing in the crowd with Superman (from this 'verse) standing near Tempus. Naturally, no one notices the uncanny resemblance, as Tempus is taken to an insane asylum.
In the 1986 Jim Henson TV special The Tale Of The Bunny Picnic, Bean (Steve Whitmire) tries to convince his older brother Lugsy (the late Richard Hunt) that he saw a dog (Jim Henson himself) in the lettuce patch, but Lugsy keeps telling him that there is no dog. It isn't until the dog attacks the bunnies' community that Lugsy finally believes him...
An episode of Space: Above and Beyond has Nathan as apparently the sole survivor of the 58th Squadron. His attempts to convince his superiors that the rest of his squadron is still alive are treated as symptoms of PTSD until almost the end of the episode.
No matter how hard he tried, Chris the Crafty Cockney in The Fast Show couldn't get people to believe the he was a geezer, he'd nick anything. People would still insist the he look after something for them, whereupon he'd nick it.
In a Tracker episode, a fugitive kills someone inside the bar after Mel lets people in during a snowstorm. Cole tells Vic about his being an alien searching for alien fugitives, and Vic naturally thinks he's crazy.
In Continuum, Kiera has to tell so many lies that it's obvious to Agent Gardiner that she isn't who she says she is. She eventually gets sick of the facade and tells him she's a time traveler, but he thinks she's messing with him.
This trope is a huge part of the Ayreon legendarium. In The Final Experiment the protagonist, Ayreon, is sent visions from the future about the end of the world and travels to King Arthur's court to warn him. Merlin is jealous, convinces everyone that Ayreon is wrong, and realizes that was a bad idea too late. He predicts that another seer will come: Mr. L in 01011001 has dreams about the end of the world sent to him by cyborg fish aliens; unfortunately, he's in an insane asylum.
Emilie Autumn's Bedlam House chic is heavily based on her belief that psychiatric institutions have not progressed that much with patient care: specifically, she alleges that abuse is rampant but never gets brought up because "[she's] the crazy girl and he's the doctor with a million dollar education".
Fear Before the March of the Flames have "Taking Cassandra to the End of the World Party", with lyrics referencing someone predicting a catastrophe while being ignored and the chorus "no one listens to the damned".
The Crüxshadows also have a song titled "Cassandra".
Numerous Biblical prophets, most notably Jeremiah and Elijah, spent much of their lives trying to convince the public in the Kingdoms of Israel and Judah that exile was imminent due to the people having strayed from the Torah's commandments, and the monarchy in particular having turned to idolatry. This was often met with hostility, particularly from the monarchy.
Isaiah 53:1 invokes this: "Who has believed our report?"
A quite magnificent example in the first episode of Series Two of The BBC Radio 4 comedy The Casebook of Inspector Steine. As it begins, Mrs Gloynes, the police station tea lady who is actually the crime boss of 1950s Brighton, has been laying low since the highly intelligent PC Twitten discovered her secret and agreed to keep quiet if the crimewave stopped. Near the end, the constable is reluctantly dragged on stage at a music hall and hypnotised to believe that "this charming Cockney charlady is a criminal mastermind". The episode ends with crime rates up again, and Steine telling Twitten that if there's no way to snap him out of this delusion, the least he could do is keep quiet about it.
Mage: The Awakening features "Proximi", families with a magical heritage, limited magic, and an unbreakable family Curse. Particularly the Primid family, said to be descended from Cassandra with a gift for prophecy, and who originally shared her Curse. They eventually tried to use it to their advantage (deliberately making predictions that they knew people would act against, as a way to manipulate them), so the Curse altered itself accordingly (the point of Proximus Curses being that they are always bad, and change themselves to fit loopholes). Now, the Primid Curse is that they are incapable of accurately conveying their prophecies at all (that is, they will know the future, but will be unable to truthfully tell it to anyone else).
Sidereal Exalted have a two-fold version of this trope. In a straight application, nobody listened to them when they tried to stop mad Solars from doing world-endangering shenanigans. In a more twisted one, they can do it on purpose, at will.
One Ork codex for Warhammer 40,000 has a flavor quote about Ork Kommandos, where the guardsman who survived the attack is executed for covering up his cowardice by inventing a story of half-glimpsed shadows. Orks being a race of Leeroy Jenkins, sneaky orks are a rarity, making them all the more effective.
There's also mention in the background of an Eldar seer named Q'sandria, a former pupil of the legendary Farseer Eldrad Ulthruan, and the only one who believes Eldrad's soul still lives despite his body being destroyed during the 13th Black Crusade. Since the timeline is frozen we don't know is she is right, but considering the name...
In the board game They've Invaded Pleasantville, a homage to alien-invasion B-Movies, the townspeople can't react to the alien presence until somebody spots the aliens and spreads the word. Certain people are unable to spread the word, because nobody else in town will believe someone known to be 1)a drunkard or 2)a Democrat.
In Sweeney Todd: The Demon Barber of Fleet Street, once Mrs. Lovett's pie shop starts doing business again, the Beggar Woman starts hanging around the shop, trying to warn people that something evil's afoot, pointing out the stench from her chimneys and claiming that Mrs. Lovett is a witch. Naturally, no one believes her because she's a mad beggar woman.
Trope Namer: Within The Oresteia, in the play Agamemnon by Aeschylus, Cassandra gives a prophecy revealing Clytaemnestra's plan to kill her husband, Agamemnon. Although the chorus does try to listen to Cassandra, they don't understand a thing she says, and eventually ask her to stop talking about such horrible things, because they would never happen.
Julius Caesar: By the time Caesar learns that he should pay more attention to soothsayers, it's too late. He also learned too late that it's not a bad idea to install metal detectors in the Senate.
In Pygmalion, act III, when Eliza is taken to a party, Nepommuck remarks that she can't be English, because her English is too perfect. Higgins replies, paraphrasing here, "Well, I think she sounds like someone taught by an expert, probably from Drury Lane." Notably, the host of the party goes with Nepommuck instead of Higgins. Obviously, Higgins was the one telling the truth.
In Macbeth: The entire play hinges on a play on words and this trope. Macbeth was warned to "beware Macduff", that Dunsinane would never be taken until "Birnam Wood came to high Dunsinane", and that he could only be killed by a man not of woman born by the witches, which he took to mean that he was invincible. However, Macduff was born by Caesarian Section, thus being not born of woman, and Birnam Wood came to Dunsinane through soldiers carrying boughs from the trees of Birnam to Dunsinane to mask their numbers.
In Suikoden III, a "mysterious sorceress" wanders into Karaya Village with a prophecy that the village will be attacked by Zexen forces and that everyone should clear out immediately. Nobody believes her, and the village is destroyed. The reason she knew about this is because she was part of the plot, and just wanted to minimize casualties.
The PokémonAbsol sense danger and natural disasters and go to the people to warn them of the upcoming disasters. However, nobody listens to them, and thus the whole species has a horrible reputation for being the ones to cause disasters.
Eternal Darkness: No, really. The darkness DOES come and will damn us all if nobody stops it, so may the rats eat your eyes for not listening to Max Roivas.
In Knights of the Old Republic 2, you arrive in Iziz spaceport looking for a Jedi master, smuggled aboard the personal shuttle of the Mandalorian leader. Feel free to tell the customs officers any of this, they won't believe a word.
The entire damn story. Specifically, it's understandable for The Citadel Council to be skeptical of a lone human warning of ageless giant robot monsters from outer-outer space coming to wipe out all galactic life, at first. But after said human and their cohorts are proven right, time and time again, in everything else they've told you, some smidgen of acceptance wouldn't kill you!
Turian Council Member: Ah yes, (air quotes) "Reapers".
This occurs within the game itself, in regards to the player. On the very first mission you encounter an apparently insane scientist that you (and the other characters) dismiss for being nuts as he's rambling. He's utterly correct about everything. One of the random planets you can scan has a description indicating it was bought by a millionaire who went nuts because voices in his head told him about an enemy he's looking for weapons to fight...he also is spot on in his description of who the Big Bad of the series is.
Lampshaded in the third game, where Legion reveals that the Geth collective believed his evidence about the Reapers returning from Day 1.
Shepard: ...That must have been nice.
The asari councilor finally gets Genre Savvy about this during the Cerberus coup. Shepard claims that Udina is leading them into a trap, as he's partially behind the coup, but gets dismissed by most of the Council and their bodyguard. However, the asari councilor points out that every single time the Council has disregarded Shepard, it's come back to bite them in the ass, and decides to hear him/her out.
You also encounter a Spectre who explains that, although the Council dismissed Shepard's warnings, many Spectres took them at face value.
Happens in Final Fantasy X, where no one will believe Tidus about being from Zanarkand.
Tidus saying that "there has to be another way to beat Sin". There is but the people of Spira are too resigned to the regular method (a human sacrifice) that they don't bother to see his point.
Played for laughs when some of the party members explain what's really happening concerning the murders, in detail, to an inquisitive detective... but because the truth sounds so absurd and the characters in question are completely drunk (sort of), they are immediately disbelieved. Said detective however is eventually confronted with the truth to her face and apologizes for not believing them before, though pointing out how absurd the truth really is. The police however flat out never believe you. Especially not Detective Dojima, who demands that the protagonist tell him what's going on, only to hear the truth and not believe it. This happens not once, but twice in a matter of moments.
Although it's played tragically with Taro Namatame, who actually suspects something after the first murder, fails to convince the second victim, and is brushed off by the cops when he thinks he knows the next target; his story was crazy and he was being played by the real killer. In fact, you can put the final nail in the coffin by not believing that he didn't murder anyone, and throwing him into the TV world as punishment.
In Arc Rise Fantasia, the party (and the player) is quick to jump to the conclusion that Rastan is Leon, which Rastan corrects at every opportunity. It comes as quite a shock that this was the truth all along, and it's a major headdesk moment when everyone realizes that Leon is actually Serge, who fits all the clues just as well as Rastan and hasn't been denying it all along. He's just not what anyone was expecting the legendary Lightning Leon to really be like.
The Prophet in Warcraft III tries to alert the human kingdoms of Lordaeron to the threat of the Burning Legion, but only Jaina Proudmoore heeds the call and takes an expeditionary force to Kalimdor. Lordaeron is destroyed by the Scourge, who bring forth the Burning Legion.
Also played with in the Warcraft Expanded Universe novel The Shattering: Prelude to Cataclysm with the old Shaman Drek'thar. His visions were still heeded despite a growing level of senility up until the point where his vision of a peaceful meeting of druids being attacked by orcs, and sending of troops to provide protection, leads to a false alarm and increased distrust by the Night Elves. Later in the book however, this attack does occur, and Drek'thar's caretaker is horrified when he realizes that, not only was Drek'thar right all along, but his most recent visions were about an upcoming Cataclysm.
In Patch 4.3 of World of Warcraft, if you talk to Bishop Farthing and tell him that Archbishop Benedictus, who supposedly left to help the Dragon Aspects, is actually the Twilight Prophet, he will first laugh it off, and if you insist that it's true, he will scold you for believing and spreading false rumors, mentioning to one he heard about Bolvar (whom everyone thinks is dead but is actually the new Lich King).
Happens to Jaina so often it may as well be called Proudmoore's Wisdom.
Glory of Heracles DS has Cassandra herself show up, and gives a different reason why her prophecies are not believed: when she tries to give them, half the words are rendered unintelligible. Only Achilles can hear her prophecies, and he gets offed pretty fast. Eventually, the party takes her into a room lined with stone that cuts off the power of the gods, and her curse lifts long enough for her to give them her prophecy (which says "Typhon is coming").
This plays into the ending of The Breach: our hero has survived, but he's a nervous wreck locked in an insane asylum, and since he blew up the spaceship to destroy everything on it, he has no way of convincing anyone of what really happened, and no way to prevent the experiment from being replicated. Then he turns into a monster and apparently eats his psychiatrist. On camera. Well, at least that ought to put a stop to the experiment...
Feizhi is essentially a kung-fu Anime Chinese Girl Cassandra. Several of the NPCs in Xian are indicated to believe her visions, after the first two came true... but her father not only disbelieves, he rebukes her for having a vision that her friend was caught in a rockslide and worrying about him, which is the part our heroes see before she runs off in tears to find her friend.
Saturos and Menardi. They tried to explain the situation to the Vale elders, but when they didn't believe them, they were forced to take drastic actions.
Chrono Trigger: After the Time Key gets stolen and you go find it, Azala asks you what it does. If you tell her, she doesn't believe you, saying if it were true, you wouldn't tell an enemy.
Kind of subverted in Skyrim, when you arrive in Whiterun and talk to the Jarl about a mythic creature from ancient legends attacking his land, he actually believes you immediately and rewards you for the warning.
In the Throne of Bhaal expansion of Baldur's Gate 2, listen to Gromnir Il-Khan's paranoid ravings about Melissan. He's absolutely right about all of it. Too bad he's also been executing other Bhaalspawn under suspicion of betrayal and now everyone thinks he's gone mad.
In The Legend of Zelda: Ocarina of Time: Zelda's claims that Hyrule is in danger and that Ganondorf might be a traitor are disregarded by the king as such. When Link has to send a letter to the guard of Death Mountain gate, the guard while he acknowledges the writing as authentic: assumes that Zelda is playing pretend.
Crysis 3: No one believes Prophet's warnings that the Ceph are back until it's too late.
In Cookie Clicker, the news ticker mentions a scientist who becomes a laughingstock among his peers for predicting a cookie-related end of the world. His prediction turns out to be scarily accurate once the Grandmapocalypse is triggered, with the news ticker announcing reports of The End of the World as We Know It.
News: scientist predicts imminent cookie-related "end of the world"; becomes joke among peers.
In Tsukihime, the day after fighting and killing Nrvnqsr Chaos Shiki is given the option of telling the truth about what he had been doing the past few days to his sister Akiha. She simply laughs at his explanation, but in reality she actually probably believes his supernatural story, being a supernatural being herself.
In Remember 11, Kokoro and Satoru attempt (and fail) to convince their respective companions that the two of them are experiencing random personality transfers.
In Hourglass of Summer the protagonist tries to warn the girls of the future events he's seen from traveling randomly through time against Lee Jane's warnings not to. It fails because nobody believes him and the tragedies happen to them anyway. Subverted by Kaho where the letters he writes to her warning her against going to the train station on the day she dies are simply never delivered by her overly controlling father.
One of Corpse Party: Blood Covered's Bad Endings has this: Satoshi finds himself sent back to the day they performed the ritual that sent them to Tenjin. Unfortunately, he can't convince anyone not to go along with it, as they all assume he's just too scared and superstitious rather than having good reason to protest. Book of Shadows actually picks up from this ending and deals with the results.
Season two sees the Reds try to figure out why Lopez disappeared, then why the Warthog later went nuts and started trying to kill Sarge. Donut actually hits on the rather bizarre correct answer: Church got killed, then his ghost possessed Lopez to use for a body, then the Blues accidentally triggered the Hog's remote control while looking for Lopez's "fix stuff" function. But the other Reds think Sarge's brainwashing beam idea is more likely, and they'd rejected that one out of hand for the Mundane Solution that the Blues reprogrammed Lopez.
At the end of the "To Thine Own Self" arc of General Protection Fault, Trudy tells the rest of the cast that she wants to stay behind in the Nega-verse and atone for what she did, knowing that it's better than going to jail for the rest of her life, and asks that they bring her counterpart to the real world. The building shakes, knocking Trudy out, and Nega-Trudy comes to, putting on the pin to make them think she's the real Trudy. She then tells them to take the real Trudy back, claiming that she will be delusional after coming to and will falsely claim to be the real Trudy. Trudy attempts to explain that she is the real one several times, but to no avail.
In this strip, Bert predicts Torg "fleeing for his life while flying by the crotch planet in the giant space crotch," and Torg reacts exactly as you'd expect. Three and a half months later, Torg and Riff are riding the crotch of "GOFOTRON" past the "planet of the naked nymphomaniacs" to escape a warlord.
Torg: Remember Oasis, the killer-robot who was ordered to love me and then blew up in a massive explosion with her creator? Riff: I was supposed to BELIEVE that? I thought it was "make up a big fat lie" day.
Kind of inverted with the Oracle, who has a spell placed over his entire valley, so that once people leave they forget everything about their stay except for whatever prophecy he gave them. So, while they're able to act on the prophecy itself, anything else that happens in the valley is forgotten, including any plot-significant revelations or information. Needless to say, visits to the Oracle usually make hilarity ensue.
Another interesting example of this: Roy, suspecting that the Oracle will try to trick them with an overly-literal prophecy, carefully words his question about which of the Gates Xykon will attack next. However, the way Roy phrases this leaves out one of the possible Gates — which, as it turns out, is the one Xykon is going to attack next. The Oracle tries to explain this, but Roy refuses to believe him, and winds up accepting the literal answer to his question instead, even though it's not accurate. He does eventually realize his mistake, though... just in time for the memory spell to come into effect, making him instantly forget it.
Yet another interesting example (though Played for Laughs) here — Haley tells the truth completely, but the others are suspicious of her — which is exactly what she wants. Haley quite often does this — with the Linear Guild and now with Elan's father. Is she the only one able to spot obviously evil people?
Explaining that he and a main character are wrongly imprisoned, Thog tells it just exactly like it is here:
Thog: not nale. not-nale. thog help nail not-nale, not nale. and thog knot not-nale while nale nail not-nale. nale, not not-nale, now nail not-nale by leaving not-nale, not nale, in jail.
TG: skepticism is the crutch of cinematic troglodytes like hey mom dad theres a dinosaur or a ghost or whatever in my room. "yeah right junior go back to bed" fuck you mom and dad how many times are we going to watch this trope unfold it wasnt goddamn funny the first time i saw it just once id like to see dad crap his pants when a kid says theres a vampire in his closet "OH SHIT EVERYONE IN THE MINIVAN" be fuckin dad of the year right there
Later played heart-rendingly straight in this memo from Karkat to the troll's past selves. During it, a few of the people who really should be paying the most attention to it miss the point or dismiss it as more of Karkat's outrageous nonsense. Namely, Feferi, Eridan, and Gamzee, who have respectively: died at the hands of Eridan, switched sides and killed two people as well as possibly blinded a third, and gone completely batshit insane and gone on a killing spree.
Arguably this counts as Crying Wolf, seeing as at this point Karkat has rambled and been a jerk for so many sweeps-worth of memos that nobody is going to listen to him, even if what he's trying to say is important.
Roxy seems to know more about Betty Crocker and her true intentions than anybody else seen so far (save for Nannasprite). However, Jane, the one person who needs to know these things the most, refuses to believe her. Jane's disbelief is justified because she's being brainwashed and Roxy is a Hard-Drinking Party Girl. Jake seems to believe what she has to say.
Later, undyingUmbrage warns Dirk (correctly) that Lil' Cal is an abomination that can only lead to pain and suffering for all, even noting that awareness of this is so important, he's willing to give the warning despite being a complete asshole. Naturally, Dirk assumes this is more jerkery and professes Lil' Cal to be his best friend.
In this strip, Marten and Dora return from a "walk" with different clothes (in particular, Marten is wearing Dora's trousers) and a completely incredible story involving kung-fu monks. Faye obviously doesn't believe them... but it turns out to be the truth.
Then here, Marten explains that he came home late with a stop sign in his hand because he and Steve were fighting off a vigilante on a vespa who thought Steve was abusing his girlfriend. Dora immediately dismissed this explanation and decided he went to a strip club and brought home the stop sign as part of a cover-up. Factoring in the part where he would've had to somehow reason that stealing a stop sign was the best way to create a cover-up, this is one of the few examples where the implausible truth is actually less implausible than the thing everyone else assumes. Also kind of funny that Faye reasons he's telling the truth because the strip club part is too far-fetched.
A Loonatic's Tale: Riley often sees unsettling or downright sinister things going on around him (like a bug zapper that can fry a songbird, or, in a particularly Fourth Wall Observer moment, the bush outside his house as seen from the perspective of a man with a cartoonishly Sugar Bowl worldview), but no one ever believes him when he tries to warn them.
In Dominic Deegan, the eponymous seer runs into this problem when he tries to convince Chance Masters and his family that an extradimensional monster will kill Chance if he participates in an upcoming tournament. They believe he is a charlatan who is trying to exploit them. A fairly justified example: Dominic had a nervous breakdown in public on his record, the threat he is trying to warn them about would be unbelievable to anyone without Dominic's unique perspective, and the Beast is invisible to most seers — Dominic can only see it due to unique circumstances. Also, the Master family had had first person experience with being conned by someone claiming to be a seer who had seen a vision of impending danger to them.
Ears for Elves: After meeting Rolan for the first time, Tanna isn't sure of what she saw — it happened too fast — and tries to explain it to Myari and Elon. They don't believe her.
Myari: Oh Tanna, you've been pushing yourself too hard! You're talking crazy!
Elon: Perhaps you should rest for a moment...
Sydney of Grrl Power is a lousy liar. But after making up half a dozen ridiculous stories about the mailing tube she always carries on her back, she gives up:
Sydney: Fine... it's full of... ancient artifacts that give me superpowers?
Joel:Fine, don't tell me.
The Fox Sister: The comic doesn't actually show it, but it's easy to imagine how Yun Hee's eccentrics of accusing her sister to be a shape-shifting fox demon after waking up in the hospital are received.
Webprose example: In Star Harbor Nights's Toymakers arc, fully half the conflict could have been avoided if everyone had just believed Claire's observations and her resulting conclusions.
#109 of the Evil Overlord List: "I will see to it that plucky young lads/lasses in strange clothes and with the accent of an outlander shall REGULARLY climb some monument in the main square of my capital and denounce me, claim to know the secret of my power, rally the masses to rebellion, etc. That way, the citizens will be jaded in case the real thing ever comes along."
In the Paradise setting, this frequently applies to characters who try to convince others that they have been invisibly transformed into Funny Animals but just don't look that way to normal people. There are ways to short-circuit the Weirdness Censor temporarily, however.
When he tries to put Rocky IV's message of "people can change" to the real world, The Nostalgia Critic gets punched and shot at.
He also tried really hard to get people to believe he didn't have a crush on JesuOtaku, but due to how much he denied it and what he's like, nobody believed him.
No matter how many times Nathan tries to convince people on the Encyclopedia Dramatica forums that Magnum is really an insane troll, the trolls/EDiots always dismiss it as 'sperging' or 'BAAAWING'.
In Worm, this tends to happen whenever Skitter and the Undersiders try to warn the heroes about a greater threat. Somewhat justified as circumstances lead the heroes to believe the Undersiders are just using disasters to gain power or are corrupting people in some way.
One episode of Batman Beyond has a Jerk Ass reporter who can pass through walls managing to get video of Bruce Wayne working with his protege, Neo Gotham's new Batman, Terry McGinnis. When Terry sees their pixilated faces on the news and his family excitedly gathering around the TV to find out just who Batman is, he feels that it would be better if they hear it from him rather than some gossip news reporter who got lucky. They laugh in his face.
The Boondocks: Huey frequently warns those around him when danger is afoot but no one ever listens to him, though he is aware of this and has a folder made specially for the instances where they do decide listen to him titled "I told you so".
When Bobby Hill tries to tell his father about something he's proud of himself for doing, Hank dismisses him because he is so used to Bobby's disappointments as a son.
When a snipe hunt gone wrong results in an endangered crane being killed, Boomhauer confesses to a park ranger and the gang thinks their cover's blown. The ranger just tells them to carry on.
Another episode has a variation, where Peggy correctly guesses events but gets the motives behind them wrong. Bobby damages Peggy's lawn gnome, and Hank uses this as a pretext to get rid of it; when he confesses, Peggy thinks Bobby is to blame for the whole thing. Later Hank buys a replacement gnome and lets Bobby give it to Peggy to smooth things over; again, Peggy assumes that Hank took pity on Bobby and got the replacement as an apology.
On Animaniacs, cartoons featuring Chicken Boo revolve around this concept. Chicken Boo, a giant chicken wearing human clothes, shows up as a renowned expert in some field. Exactly one person immediately sees through the Paper-Thin Disguise, and is exasperated that no one else will believe that "He's a chicken, I tell you, a giant chicken!" In one of the first Chicken Boo stories, "The Man with no Personality", it's possible that the townsfolk thought the Cassandra-Man of the story was accusing Boo of being a coward.
In one episode of Batman: The Animated Series, Hugo Strange, who had discovered Batman's identity, told it to the Joker, the Penguin, and Two-Face; all three thought the idea of Batman being Bruce Wayne was absurd. (The Joker's reply was, "And people call me crazy!")
Two-Face said he didn't believe it because he knew Wayne, and figured he would have known if Wayne were Batman. Indeed, as Harvey Dent he had been a close friend of Bruce.
Security Guard at the White House: Aren't you a little small to be wallpaper hangers? Brain: Actually, we are two lab mice trying to take over the world. Security Guard at the White House: Oh, you silly wallpaper hangers. Go on in.
Jet goes through this when trying to warn people that Zuko and Iroh are firebenders that are trying to infiltrate the city. After spending several days trying to get proof, he loses all credibility when he decides to suddenly attack them in front of a bunch of customers to get them to firebend in defense, which leads to his capture and Brainwashing by the Secret Police. The sad thing was, in that instance he was wrong in his fears. Those firebenders weren't trying to do anything evil. It just makes the second season ending really ironic.
In Jet's first appearance, Sokka also went through this while trying to convince Aang and Katara that Jet planned on wiping out a village just to take out some Fire Nation soldiers stationed there. Jet's plan would have worked as even the towns people didn't believe him until the elderly man that Sokka saved earlier backed him up.
Invader Zim: Dib is the only human who instantly recognizes Zim as an alien dangerous to humanity. A Running Gag throughout the series involves him trying to reveal Zim's true species to the world, only to have no one believe him, either due to Dib acting too crazy to be believed, through Zim's counter actions to protect himself, or the people in the Invader Zim world being drooling morons. Interestingly, Dib's sister (Gaz), knows full well Zim is an alien, but says almost nothing about it, mostly because she believes (with quite a bit of justification) that Zim is too incompetent to be a threat.
One noticeable example where just after Zim claimed himself to be a human at school, his giant alien boss comes through the ceiling and jetpacks with him away. Dib tries to finally get the students to open their eyes but all they noticed is the bird poop that just landed on Dib's head.
Bart is attacked by a wolf at school. Naturally, because he's "cried wolf" so many times before, no one believes him, even when he had signs that he had been mauled.
"Simple Simpson" has Homer taking on a superhero identity: Pie Man, who throws pies into the faces of wrongdoers. Towards the episode's end, rather than submit to an attempt to blackmail him into pieing the Dalai Lama, Homer outs himself as Pie Man. Nobody believes him as they all think Homer would never be smart enough to even come up with a secret identity in the first place.
Homer has been barred from Moe's Tavern, and has borrowed an airline uniform in order to gain access to the pilot's bar:
Man: We need a pilot, pronto!... You! Homer: But I — Man: Hey, you're not just impersonating a pilot so you can drink here, are you? Homer: Yeah. That's exactly why I'm here. Man:(laughs) You fly-boys, you crack me up! Homer:(being pushed into the cockpit) But I keep telling you I'm not a pilot! Man:(brusquely) And I keep telling you you fly-boys crack me up!
In "Hungry, Hungry Homer" Homer goes on a hunger strike because no one will believe him when he finds out that Duff Beer is planning to move the local baseball team to Albuquerque. Homer even provides a fitting quote for this trope, which you can see on the quotes page.
Lisa: Mom! Dad! Mr. Burns is a vampire, and he has Bart! Mr. Burns: Why, Bart is right here. Bart:(monotone, with noticeable bite marks) Hello, Mother. Hello, Father. I missed you during my uneventful absence. Homer: Oh, Lisa, you and your stories. "Bart is a vampire." "Beer kills brain cells." Now let's go back to that... building... thingy, where our beds and TV... is.
In "Treehouse of Horror VI", Homer is abducted by Kang and Kodos who tell him that they plan to kidnap President Bill Clinton and Senator Bob Dole and take over Earth during the 1996 Presidential campaign. Homer tells the aliens that he is going to tell everyone and put a stop to their evil plan. They spray him with rum and then send him back to Earth, saying that no one will believe him. When he gets home and tells the family, no one believes him because they think he got drunk at Moe's.
Chief Wiggum treats everyone like they're telling Cassandra Truths. Even to the point where an obvious arsonist walks into the station to give himself up. Wiggum dismisses him as a loon not worth listening to.
Young Man: You can't treat the working man this way! One of these days we'll form a union, and get the fair and equitable treatment we deserve! And then we'll go to far, and become corrupt and shiftless; and the Japanese will eat us alive!
Burns' Grandfather: The Japanese?! Those sandal-wearing goldfish-tenders? Bosh!Flimshaw!
Candace suffers from a severe psychosis because she can't convince her mother that her little brothers make a habit of violating the laws of common sense, physics, or current technological progress. Every time she tries to expose them, some remarkably convenient plot device eliminates the evidence just as their mother arrives on the scene. Her mother has commented on this being a delusion, making it reasonably close to an accurate adaptation of the original portrayal.
For that matter, she doesn't believe Phineas and Ferb when they back Candace up, merely assuming they're "imaginative". Actually a subversion, as it seems Linda's the only person in Danville that doesn't know about at least one of Phineas and Ferb's projects. (With the exception of the animal translator in "Interview with a Platypus", where she thought that it was cute but didn't get suspicious at all.)
Mirroring Candace's problem (but not getting so worked up about it) Doofenshmirtz's daughter Vanessa can't convince her mother that he's an evil Mad Scientist.
Whenever Phineas and Ferb are getting industrial supplies trucked into the backyard, the contractor will look at Phineas and ask, "Aren't you boys a bit young to be doing this?" and Phineas'll respond, "Why, yes, yes we are." Word Of God is that they think the two are child prodigies (why else would they be ordering all of these things?), and if the delivery people were actually smart enough to not give them the items, they wouldn't accept them. How accustomed the delivery people are to Phineas and Ferb's strange orders is lampshaded in one episode where there are two contractors, one noticeably younger than the other. The young one says the standard "Aren't you a little young for this." To which the older contractor quickly says "Sorry Phineas, he's new."
Almost everyone in Code Lyoko that doesn't actually see the Supercomputer for themselves have an extremely hard time believing it exists. Not that they ever remember they were told about it in the first place... Most notable example is the second episode, "Seeing is Believing", where Yumi tries to convince the principal and some firefighters that XANA is launching an attack on a nuclear power plant. Nobody believes her.
Similarly, the Canadian cartoon Kid vs. Kat falls under this when an alien-looking cat ends up being taken in (and accidentally stranded on Earth) by an unsuspecting family. Save for the son, Coop, who's rightly convinced the cat has evil intentions leading into conflicts between the two. However, most of their scuffles end up with Coop holding the bag and no one believes him when he tells what really happened.
In the episode "Identity Crisis", Venom has revealed that Peter Parker is Spider-Man. The common reactions throughout the large cast of the show are laughter, disbelief, and momentary consideration ("it would explain a lot...").
Aunt May (looking around for hidden cameras): Am I being punked?
In another episode, a group of villains working for the Kingpin kidnapped Aunt May, leaving a ransom note demanding that Peter send Spider-Man to their headquarters. The plan worked, but when they overpowered Spider-Man and unmasked him, only the Rhino believed at first that they had caught the real Spider-Man. The rest all thought that Peter had been unable to find Spider-Man and had come disguised as him. (The fact that Spidey had temporarily lost his powers and had put up a pretty pathetic fight was probably the biggest reason.) In fact, Silvermane was disgusted with the Kingpin for "doing nothing but grabbing a harmless old woman and her nephew", which he didn't seem to take well...
Stan finally decides to come clean and tell the town that he destroyed a beaver dam and caused a massive flood in a neighboring city. The adults of the town, being complete idiots, interpret this as him saying that everyone in South Park is to blame for the destruction of the dam. The episode ends with everybody in the town saying "I broke the dam," and Stan's yelled confession being ignored completely.
In "Spookyfish" when he tells his mom that his fish is killing people, she doesn't believe him.
In "The Biggest Douche In The Universe," Stan makes his own rival show to John Edward's "Crossing Over." He begins every episode by saying that his (and Edward's) statements and "communications" were simply tricks and hoaxes. No one believes him.
In "Cartman's Incredible Gift" Stan and Kyle know who the serial killer in this episode is, but the police refuse to believe the two of them and only listen to fake psychic Cartman, who's just using them to arrest anybody he has a grudge with. Kyle, being Genre Savvy enough, realizes that the only way the idiot police will listen to him is if they think he's a psychic as well, and repeats the same accident that gave Cartman his "powers" on himself.
"Le Petit Tourette" has Cartman faking Tourettes Syndrome in order to get away with cursing at everyone, especially towards Kyle. Kyle knows Cartman is lying yet again and tries to tell the leader of the Tourettes Syndrome support group that Cartman is faking it, but the guy refuses to believe Kyle and thinks he is just being intolerant.
In Mystery of the Urinal Deuce, the reason why the government runs all the conspiracy theory websites for 9/11 is because 1/4 of Americans are retarded, and refuse to believe them when they tell them what actually happened.
Hey Arnold! has a hilarious example involving Curly and a football game. Every time the team leader attempts to make a play during huddle, Curly tells him to "Just give him the ball". After being ignored multiple times, Curly irritates the leader so much that he lets him have the ball. During said play Curly then uses his subsequent ballet lessons to his advantage, plié-ing away from others to avoid being tackled, making a touchdown. This makes his team very happy, until Curly runs off into the distance, still holding the football and laughing maniacally.
Occurs in an episode of The Penguins of Madagascar. While on night watch duty, Private consumes too many sugary snacks and ends up on a serious sugar buzz, when he sees a "sky orca" (shortened to "skorca"). He tries in vain to convince the other three penguins, both of whom only look for it when it's not in the air. They even fake being attacked and carried off. Later on, they (along with the lemurs and Joey the Kangaroo) find it and defeat it for real, unaware that it was actually a parade float.
On Family Guy, no one believes Peter when he says he heard the world was going to end at midnight from a chicken-man. Since the episode was All Just a Dream, it wasn't real anyway.
Subverted when Princess Celestia responds to Twilight Sparkle's discovery that Sealed Evil in a Can Nightmare Moon is about to escape her confinement by telling her to get her head out of her books long enough to make some friends. Ultimately, though, the case proves to be that Celestia knew that Twilight was the one in the best position to defeat Nightmare Moon, and sent her to a place she would potentially make the friends she needed to fully use the Elements of Harmony.
Later played straight in "Swarm of the Century". While everyone else is trying to drive the Parasprites out of town, Pinkie Pie is running around looking for instruments. At first she's just passed off as being 'typical Pinkie Pie', and eventually yelled at for getting in the way- until it turns out the only way to get rid of the Parasprites is to lure them away with music. Of course, it didn't help that Pinkie never actually told anyone what she was doing...
In Rollbots, No one believes Spin that Vertex is actually a Spider, and they have even greater difficulty believing that he is the one orchestrating all of Flip City's crime. Only when Vett appears does anyone consider Spiderbots a viable idea, but only Penny accepts that Vertex might be a criminal mastermind. However, it turns out that Captain Pounder and Ms. Appie knew the whole time.
In one episode of American Dragon Jake Long, Jake is trying to get some money off Rotwood, so he takes a picture of himself as a dragon and gives it to him. Rotwood tells him that the picture is clearly a hoax, as it's too good for an amateur to take. So Jake gives him clippings of his claws and scales, but he still refuses. Why?
Rotwood: Everyone knows that dragon claws glow in the dark, and their scales have the faintest hint of lavender.
Jake: (disgusted) That's crazy! You wouldn't know a dragon if it took a bite out of your butt!
Lance warns the King of Galaluna about the invasion in the Whole Episode Flashback of Sym-Bionic Titan, and is dismissed as a lunatic. Said invasion shows up not long after. Earlier, in another Whole Episode Flashback, Lance as a child was grabbed from his bed and dumped in the hall in his underwater. The headmaster of the academy treats it as if Lance did this deliberately, despite the student body being well-aware of Baron's Jerkass behavior.
At the end of the episode of The Batman "Riddled", after the Riddler has been taken into custody, he tells Chief Rojas that Detective Yin is working with Batman. Rojas calls him a lunatic and tells the other officers to get him out of his sight. (Rojas had a good reason not to believe him; he had not seen Batman at all during the whole crisis, and had no idea that the hero was involved, so by his reasoning, the idea that the criminal could know something like that was absurd.)
In The Amazing World of Gumball, Gumball gave an excuse letter to Miss Simian that their dad ate their homework. No one rally believed it till the end Richard confessed that he really did eat their homework.
When Jack's mother, June, angrily asks him why his motorcycle (actually Arcee) has been out when he's supposed to be grounded on Transformers Prime, Jack decides to come clean and admit that he's partnered with a transforming robotic alien being who's fighting a shadowy war against the Decepticons. When June doesn't believe it (due in part to Arcee's refusal to transform and back him up), she grounds him worse. Later in the episode, June is kidnapped by the Decepticons, and while rescuing her, Jack goes, "I can explain!" before thinking a moment and adding, "Wait, I already did."
Carroll Edward Cole arguably qualifies as a particularly frightening Cassandra. From the Wikipedia entry: "He attempted suicide at least once, and on a number of occasions, had himself committed to mental hospitals where he confessed his fantasies of murdering women. Although diagnosed as a psychopath, Cole was usually discharged promptly, as he had a personality disorder, as opposed to a mental illness — the former was considered to be untreatable by psychiatrists at the time, unlike the latter." In his later career as a serial killer, Cole claimed 16 victims.
One of Al-Qaeda's spokesmen released a furious attack on 9-11 conspiracy theorists who believe that Al-Qaeda did not plan and execute the 9-11 attacks. They even went so far as to claim the predominantly Shiite country of Iran was backing the conspiracy theorists to discredit Sunni terrorists. Even funnier because The Onion had released a parody news report earlier that year that was the same thing, triggering a Hilarious in Hindsight moment.
In addition to this, many 9/11 conspiracy theorists believe themselves to be telling Cassandra truths.
The book Dead Men Do Tell Tales relates the story of a bitter old man who regularly threatened his neighbors by declaring he had murdered his son-in-law and buried the body in a septic tank, and he would be willing to do the same to them. When the old man died, they cleaned out his house... and found the son-in-law's corpse in the septic tank.
The Monty Hall problem.  Magazine columnist gives an answer to a math problem. Mathematicians around the country tell her she's wrong. So what does she do? Write a letter of apology? No. She asks elementary schools around the nation to prove that mathematicians can't do math. She's right! The difficulty of the problem aside, they said she was wrong and she proved they were wrong about her being wrong.
During the 1964 Republican National Convention, Presidential nominee Nelson Rockefeller was met with a chorus of boos when he made a speech warning that fellow nominee Barry Goldwater was too far to the right to be elected. The Republican nomination went to Goldwater anyway, who was eventually defeated in a landslide by incumbent Democratic President Lyndon Baines Johnson. The Democratic campaign featured the now famous "Daisy Girl" ad which hinted that Goldwater was belligerent enough in his politics that he'd lead the country into a nuclear war that better diplomacy would have avoided.
Martha Mitchell, wife of Nixon Attorney General John Mitchell, claimed that President Nixon and the White House were engaged in illegal activity. She was diagnosed as being mentally ill.
In 1992, Sinead O'Connor tore up a picture of Pope John Paul II during a performance on Saturday Night Live to protest sexual abuse of children within the Roman Catholic church. At the time it was enormously controversial, but less than 20 years later, multiple incidents of the church's abuse of children, and coverup of the abuse, became an international scandal. The problem was that by going for the shock of tearing up the photo of one of the most beloved popes in recent memory, she underminded her message by attacking one of the people least connected to any of the sexual abuses that was going on. Doing it on Saturday Night Live, as the weekly musical guest, completely out of the blue and not detailing why she ripped the photo at the time did not help.
Strangely, famous magician Harry Houdini sometimes became the Cassandra. He consistently told people that everything he did was a trick and not magic. Still, many people, like Arthur Conan Doyle, insisted that his tricks were magic.
When he was young, a hypnotist visited Mark Twain's town. His friend went up, but was less than a perfect subject. Just to get attention, young Samuel went up and did everything the hypnotist told him to, even hurting himself. When he went back to visit his elderly mother, decades later, he confessed, only to find that she actually argued with him that the hypnotism was real.
During the American Revolutionary War, George Washington was prepping for his famous attack on Trenton. The entire attack could have been derailed had Johann Rall, the Hessian commander, listened to the spies and deserters who repeatedly warned him of the impending attack.
In one of the Animorphs Megamorphs books (the third) this is exactly what happens as part of the Big Bad's plans to rewrite history. The result? Washington dies, as does Jake, the leader
A strategist told the Navy that, thanks to advances in aircraft carriers, Pearl Harbor would be highly susceptible to aerial attack, especially if the Honolulu-area airbases kept their aircraft so close together. The people in charge said that such an attack was impossible, and if it did happen, it'd be unlikely to be very large. Sabotage was the bigger threat. The aircraft were kept together, in the middle of the field, where they could be watched. The result: the QUITE LARGE Pearl Harbor attack was able to wreck virtually all of Hawaii's USAAF aircraft on the ground.
Militaries tend to be the epitome of bureaucratic inertia, generally changing tactics only when their previous ones become completely untenable (whether due to lack of men or materiel or political issues). It's often said that they prepare to fight the last war.
It gets worse: an aviation-minded admiral, Harry Yarnell, "attacked" Pearl Harbor with carrier-based planes in February 1932 (on Sunday the 7th, no less) during a war game. If the bombs and bullets had been real, the place would've been a wreck and while the opposition were unable to find his fleet for 24 hours, ample time to get away for a real enemy. The powers that be lied, claiming that his planes were never in the right positions to do that much damage and they kept this line even after Admiral Ernest King duplicated the attack in a later war game in 1938. The 1941 Japanese attack came from the same direction Yarnell took and used the same persistent cloudbank for a concealed approach as the one not quite ten years later.
And just for another kick in the balls, the Peruvian ambassador in Japan had warned the US of an imminent Japanese attack beforehand.
On the other side, the Japanese architect of the attack, Admiral Isoroku Yamamoto, warned that if Japan waged war with the USA, they would have the advantage for six months after which USA would get the upper hand and keep it. Japanese government didn't listen and six months after the Pearl Harbor attack, the Japanese fleet is irretrievably crippled as an offensive force at the Battle of Midway.
Political Correctness Gone Mad: In both that trope and its inverse, this trope is in effect. Legitimate concerns about certain groups may be classed as bigotry and legitimate objections to bigotry may be dismissed as idiotic.
The tragic story of Robert Turner, a six-year who dialed 911 when his mother passed out, only for his call to be treated as a prank, leading to the death of his mother.
A general meta-instance of this can happen if one tries to explain a series with high levels of Mind Screw to someone who has no knowledge of it, particularly if they've actually asked for information. It's not uncommon for the reaction to a completely truthful answer about Metal Gear Solid or Neon Genesis Evangelion to be something like, "You're just making all this up."
Sadly invoked in many real life cases of bullying, you can tell your teacher about all the (often horrific) traumas that you suffer, but until you show up with a black eye/bleeding/seriously injured/found unconscious, don't expect anyone to believe you, and rarely for the bully to actually be disciplined. (And you'll be lucky if they do punish them.)
After World War I, most people in France's military establishment believed that the best way to defend against a future German invasion was to build a large fortress wall across the border to defend against it. The result was the Maginot Line, a barrier that Charles De Gaulle repeatedly insisted was ineffective and would not protect France from German attack, as they could simply go around it. No one believed him. Guess what happened when World War II came around?
Answer: the Germans did what they were expected to do, with two exceptions. No one on the British or French side expected the Germans to be stupid enough to attack the Line directly, so they knew they'd be forced to go around the north, and the two countries' plans were based on that (the reason the French built the Line was because, after the losses in World War One, they didn't have a large enough army to defend the entire border, so the goal was to force the Germans somewhere a defending force could be concentrated). The two surprises were the German paratroop attack on the Belgian fortress of Eben-Emael, the capture of which gave the Germans more room to maneuver and forced the Allies to hastily redeploy, and their attack through the Ardennes which was considered too dense to move effectively through. The real Cassandras were the advocates of armoured warfare, like DeGaulle, who realized that forcing tanks to merely be infantry support and spreading them out instead of concentrating them was not using them effectively.
A pity, because the French had some damned good equipment, especially the Char B1 (at 10-to-1 odds it would still come out on top against Panzer IIIs and IVs).
The biggest Cassandra of all? Winston Churchill. He'd been warning since 1933 how much of an issue Hitler might be, but he wasn't believed until it was too late to avoid war.
It's more complicated than that. People like Chamberlain was almost certainly aware of an inevitable conflict with Germany and/or Japan, and his strategy of appeasement was more a means of giving Britain enough time to build up a military response. Churchill simply insisted on attacking sooner, rather than later.
Britain, France, and the rest had the resources to thrash Hitler when Germany went after Czechoslovakia. But Chamberlain believed the (false) assurance that Germany wouldn't cause any more trouble once they had 'helped' the Germanic peoples living in Czechoslovakia's territory. False, because, see next entry.
No, the biggest Cassandra was probably Hitler himself. He made his goals very clear in Mein Kampf, but almost no one took him seriously.
Speaking of WWII: "Where they burn books, they end up burning people".
Ferdinand Foch, Marshal of France in World War I said that the Treaty of Versailles that officially ended the war in 1919 was not a peace but "an armistice for twenty years."
Starting in 2000, financial analyst Harry Markopolos spent approximately eight years trying to warn the Securities and Exchange Commission that Bernie Madoff was running a Ponzi scheme. He went so far as to send them a detailed memo entitled "The World's Largest Hedge Fund Is A Fraud" that listed 29 reasons why he was suspicious of Madoff. The SEC paid very little attention to Markopolos, leaving Madoff free to keep swindling people out of their money until his 50 billion dollar Ponzi scheme finally collapsed in 2008.
There was a documentary on the subject where a number of people had stated they saw this coming, but when they warned others, specifically in the Jewish community, they were shouted down for their statements because Madoff had kept up the appearances of being an affluent philanthropist, especially to charities geared at the Jewish community.
There's an old story about Richard Feynman (he recounts it himself Surely You're Joking, Mr. Feynman!), about two guys in his college dorm who were noisily obsessive about the door to their workspace being closed at all times. So one day, as a prank, Feynman stole the door. Eventually, after several days of no one being able to find it, a meeting was called and all the residents were charged on their honor to admit whether or not they stole the door. When it came around to Feynman, he said, "Yeah, I stole the door." "Stop joking around, Feynman, this is serious." When Feynman finally returned the door and once again reiterated that he'd stolen it, everyone asked him why he hadn't owned up at the meeting; all anyone could remember was that they'd gone away under the impression that no one had admitted to taking it.
A prime, and quite disturbing, example of this kind of Cassandra Truth is the very unfortunate story of journalist Gary Webb. In the late 1990's, he published a series of articles that detailed CIA drug smuggling from Nicaragua and other countries into the USA and how much of the drug dealers involved seemed to target poor blacks. The mainstream media, and some alternative news sties, went absolutely haywire. They viciously attacked and smeared Webb, and caused him to lose his career and his reputation. The kicker? Less than a year after Webb's articles were published, a investigative committee led by federal prosecutor Fredrick Hitz published a report that confirmed everything Webb had talked about. Yet it wasn't until after Webb's death in 2004 that any of the media acknowledged they had really dropped the ball. Worse still, many more people, media or otherwise, continue to selectively forget the entire affair.
Almost the exact thing happened with college professors of Arabic who were discouraging people from entering into Arabic classes to thwart the CIA (who was funding students to recruit Arabic speakers in their war on terror). The whistle blower was unable to convince anyone that the story was true, it simply seemed outrageous, until 6 months later they found emails between language professors all across the US detailing the truth of it all.
Happens frequently on the show Untold Stories of the E.R., which is about real E.R. doctors and nurses and the weird situations they encounter. For example, one episode had a schizophrenic patient who kept claiming that he had someone else's face. The doctors just assumed that he was off his meds and hallucinating until he showed them his drivers license and the picture actually looked different. Turns out the poor guy had lung cancer. Another one was a father who claimed worms were coming out of his infant daughter's hands and he turned out to be right.
During World War II on the New South Wales South Coast there were once two brothers at a remote beach and they witnessed a Japanese submarine’s crew land to take on more water. The older brother hid the younger one while he ran off to the nearest police station to tell the authorities. The police did not believe him and locked him up over night while the other brother was still out there. Needless to say this story has become legendary in the local Eurobodalla Area
Former baseball slugger Jose Canseco wrote a book about his time in baseball which pointed the finger at several of his teammates taking steroids. He goes into detail about certain players, most of the All Stars, would go about using them. Due to Canseco's less-than-pleasant personality, this all was completely brushed off as him trying to make some money. Then came the Mitchell Report and it turns out Canseco was telling the truth.
"One day, the Great European War will come out of some damned foolish thing in the Balkans." - German Chancellor Otto Von Bismarck, nearly twenty years before the start of World War I.
In 1916 the Italian chief of staff Luigi Cadorna received warnings of an impending Austro-Hungarian offensive in Trentino, including a detailed report from a deserter that detailed the date, location, goals, troops and the name of the operation (Strafexpedition, punitive expedition). He dismissed it all, as he thought that nobody would launch a major offensive through the mountains. The Austro-Hungarian offensive was halted only because the Russians attacked on the other side of their empire, forcing the redeployment of the reserves.
Cadorna wouldn't learn. Over a year later he started receiving warnings from the Italian Second Army, the intelligence and another deserter about an impending Austro-Hungarian offensive at Caporetto supported by German troops, but, knowing the Austro-Hungarian army was about to just break from attrition (exactly what he had tried to accomplish during the war), he decided they were too weak to try it a major offensive. The Italian defeat at Caporetto was so devastating that the Italian word for 'absolute and total defeat from which you won't recover so easy' is Caporetto, and Cadorna was sacked even before the allies requested it as condition to send support.
After all of Boeing's 787 Dreamliners, the company's flagship wide-body airline and intended replacement for the venerable 747, ended up grounded due to battery failures, it later emerge that Boeing's biggest competitor, Airbus, warned them of the risks associated with the batteries, but were ignored. Oops.
Probably THE defining tragedy for 80s schoolchildren is the Challenger shuttle disaster. Shortly after launch, one of the booster rockets partially separated from the launch assembly and ruptured its fuel tank; the laws of physics took over and tore the whole thing apart, resulting in loss of all hands. The culprit - cold weather caused a sealing o-ring to contract and allowed fiery hell to leak out of the rocket - had been discovered months earlier by an engineer during testing. The rush to meet deadlines, make the launch window, and impress the government and the public resulted in his warnings being silenced.
Many doctors assume people complaining of chronic pain are just junkies trying to score painkillers. This occurred in both Scrubs and Greys Anatomy.
Some of Jeffery Dahmer's victims could have been saved. A 14-year-old boy apparently escaped from Dahmer's apartment, and was found by two women who recognized him as a local child who didn't speak English. The police insisted nothing was wrong, and turned the boy over to Dahmer, who claimed it was his 19-year-old boyfriend and that the two had had an alcohol-fueled dispute. That the boy was naked, drugged, and bleeding rectally did not sway the officers. Nor did they make any attempt to communicate with or identify the boy. Nor did they run a background check on Dahmer, which would have revealed that he was a convicted child molester. Nor did they investigate an unusual smell in Dahmer's apartment, which would have revealed a decomposing body. Dahmer would kill the boy that night, and four more people before being arrested.
The Titanic had several of these. At various points people spoke about many of its most major design flaws, (and not just the ones that made it sink) and yet all of these were ignored. Most notably out of these were the fact that its water tight doors compartments only extended up a few decks which could allow water to simply spill over the top into the other compartments if things got bad enough, which it did, and that there where not enough life boats for all the people to escape if rescue did not arrive on time, which it didn't. Correcting both of these would be expensive and cosmetically unappealing, so no corrections were implemented.
An episode of "Mystery Detectives" (once known as "Forensic Files") focused on the murder of an escort. The woman had been called from a phone that was traced back to a house. In the house, the cops found the gun that had been used to shot the woman, and her blood on a pair of shoes in the owner's closet. When the man was arrested, he claimed that someone must have broken into his house to use the phone, stolen the shoes and gun, then replaced them after the murder. The man's explanation seemed ludicrous—until testing revealed that his DNA and fingerprints didn't match what was found at the crime scene and that his alibi was solid. Further questioning of the man revealed that several of his friends had a spare key to his house. When DNA and fingerprints were matched to one of them, it became clear that what the man had suggested was in fact true, though whether this was a deliberate attempt by the real killer to frame him or to merely cover his tracks is unclear.