Cassandra Did It

When authority figures, particularly incompetent ones make a bad screw-up, they're going to need a scapegoat to pin the blame on. In a related plot, the entirety of stage one pretty much consisted of our hero attempting to warn said authority figures of what was going on, only to be brushed aside as being irrelevant.

Well, hey, since this catastrophe was entirely unpredictable, there's only one logical explanation. Clearly, Cassandra initiated this whole devious plan, and the only way we have of stopping it is to get rid of Cassandra once and for all!

As idiotic as this kind of reasoning sounds, it is possible to use it in such a way that's not completely stupid. The Unintelligible may have shown up for the sole purpose of warning us about the catastrophe, but if we can't understand him, well, blaming him for the problem makes as much sense as anything else. Additionally, once Cassandra has been revealed as knowing something, the idea that she's an accomplice is plausible- although, since she's trying to warn you, treating her like a criminal is still pretty dumb. However, with certain subjects, their warning may be taken as a threat.

It may go without saying, but this shows up commonly in Real Life, particularly in regards to the War On Straw.

A possible outcome of a Cassandra Truth, as well as a potential fate of the Ignored Expert. Related to Shoot the Messenger.

Anime & Manga

 * This happens to an Elgyem in episode 33 of Pokémon: Best Wishes.
 * A villain in Dragon Ball GT twisted this to his advantage, threatening a village with the earthquakes he could only detect.

Comics

 * In volume 5 of Empowered, the Superhomies (especially Major Havoc) blame Emp for the trouble caused at the Capeys, since she "so obviously" could never win a fight against a supervillain on her own and must ahve planned it and may even be a closeted villain herself. The telepath Mindfuck reads Emp's mind and sides with Emp, but Havoc doubts Mindfuck's abilities and still thinks Emp had something to do with it and issued a gag order on all public discussions on the matter, leaving Emp unable to defend herself publicly against the already-started rumors.
 * This happens to Dusk in the DC Comics Crisis Crossover Final Night. She arrived on Earth and announced the Sun was going to get eaten. The Sun was then eaten. Obviously her fault.

Film

 * A lot of the conflict of The Frighteners arises when people who think Frank is a complete fraud (rather than just running a Monster Protection Racket) interpret his warnings as threats.

Folklore

 * An old Paul Bunyan tall tale has the logger stumble across a pair of mysterious whimpering shoes. Sometime after it whimpers, something incredibly strange happens, such as it raining upside-down. The other lumberjacks demand the Paul get rid of the shoe (sort of hard to blame them since stuff this weird only happened right after Paul found the shoe), but Paul, realizing the shoe's value, keeps them hidden away, only bringing them out when he was playing poker with lumberjacks who wouldn't recognize them.

Literature

 * This happens in The Passage when Amy shows up at Jaxon's village.
 * According to the Fantastic Beasts and Where to Find Them book that was released for charity, Augeries in Harry Potter are feared because they're said to prophesise death.
 * This is one Alternative Character Interpretation concerning the Mothman, which appears in fiction in The Mothman Prophecies.

Live Action TV

 * This set in motion the plot of Psych.
 * Often happens to Gary when he trys to fix the next day's events that he read about in the Early Edition.
 * According to the eponymous detective of the BBC series Sherlock, certain members of the London Metropolitan Police have assumed that the self-proclaimed sociopath demonstrating extensive knowledge of the crime and attempting to insert himself into the investigation must be the killer. No kidding?

Music

 * The Iron Maiden song "The Prophecy".

Video Games

 * The Pokémon Absol is considered a bad omen, because it is only ever seen before disasters strike. Of course, it can predict disasters and is just trying to warn people.

Web Comics

 * In a Jaws parody storyline in Schlock Mercenary, Der Trihs tells the authorities that a shark is behind the killings, but they don't believe him because sharks aren't native to that world. He sarcastically suggests that it must have been a stealth submarine with a shark-jaw mechanism, and they immediately decide that Der Trihs is responsible, and it was his stealth shark-submarine, and arrest him. Even when the Mad Scientist who created the sharks confesses, the police are convinced that he was Der Trihs's co-conspirator.

Web Original

 * In the Neopets plot "The Curse of Maraqua", two sisters with the gift of foresight deal with this trope. The first sister, who sees happy events in her dreams, is lauded and welcomed; the other, who sees bad events in her nightmares, is feared and shunned.

Western Animation

 * Pretty much every episode of Kid Vs. Kat
 * My Little Pony: Friendship Is Magic, "Bridle Gossip": Twilight and friends confront Zecora, a mysterious zebra who lives in the Everfree Forest and whom everyone suspects of being a witch. Zecora departs into the woods with a cryptic warning about "those leaves of blue" the ponies are standing near, which the other ponies assume is some kind of curse. Sure enough, a weird affliction strikes the ponies the next day, and guess who they blame? Naturally, Zecora has nothing to do with their condition, and it turned out to be the fault of the blue-leaved plants they were walking through earlier, which are actually a magical plant called "poison joke".
 * A variation of this occurs in Earl Cooper's backstory in the Batman the Animated Series episode "The Mechanic". He was instrumental in blowing the lid off a scheme perpetrated by Global Motors. When he realized their newest model had a potential lethal safety defect that threatened lives, he was nearly killed by his employers in an attempt to silence him, but was saved by Batman. While he exposed said employers for the crooks they were, he would, for years afterward, be labeled a whistleblower, unjustly blacklisted by the industry, "unable to get a job as a grease monkey", as he put it. That is until, at the end of his rope, Batman appeared again, telling him simply: "I need a new car."