D�j� Vu

Orson: Roy, I have the strangest feeling that we've done this cartoon before.
Roy: Maybe it's a rerun?
Orson: No. When you get the feeling that you're doing things you've already done, do you know what that's called?
Roy: The writer running out of ideas?
Orson: No!
Roy: Because that happened halfway through the second season.
Orson: It's called déjà vu.

— Garfield and Friends, from the U.S. Acres segment "Déjà Vu"

Déjà Vu, literally "already seen" in French, is a sensation of having already lived through what's currently happening. In real life, it's just a regular anomaly of memory recall. In fictionland, it's a sign that something isn't quite right.

Commonly experienced by characters who are starting to realize they are part of a "Groundhog Day" Loop. Occasionally appears in Time Travel plots. Truth in Television and a source of Paranoia Fuel in Real Life. Related to A Glitch in the Matrix, Déjà Vu may be a symptom of encountering that trope. May be triggered by passing through a Door to Before. Sometimes used for an Oh, No... Not Again! gag.

An inverse phemonomen, "Jamais Vu", meaning "never seen", also exists. It is the sensation of being in a situation that you logically know you should have experienced before, yet somehow seems unfamiliar and/or novel.

If you are looking for the album, go here. If you are looking for the film, go here. If you are looking for the game, go here.

Examples:

open/close all folders

Anime & Manga

Mushishi: One chapter involves Ginko meeting a man who is lured by a mushi, that causes him to go through a "Groundhog Day" Loop over and over. The result being the man is constantly having a lingering feeling of déjà vu, but since the loop begins at his childhood he doesn't remember what is causing it.

Comedy

George Carlin had a bit on what he called "Vuja De," a sensation that what is going on has never happened before.

Comic Strips

The Far Side. A hippie stops at a house to ask for directions; upon noticing that the person he's speaking with is an elephant-bird-giraffe-man, he says, "Oh, wow, déjà vu."

Fan Works

A Diplomatic Visit: In chapter 26, Twilight experiences a brief moment of this when her Equestrian friends unintentionally quote her Canterlot High friends (with Spike getting Rainbow Dash's line).
In Star Trek: Voyager Parody Fic "A Fistful of Mammary Gland," the Woman With No Name (just a number: 7 of 9) boards a spacecraft whose crew are split into two factions, Starfleet and Maquis, in a constant state of conflict. She has the feeling that this scenario has been played out before.

Films — Animation

In Inside Out, Bing Bong points out several parts of Riley's mind, saying "There's déjà vu!" after naming each one.

Films — Live-Action

Cat Women of the Moon: Helen the navigator is able to guide the rocketship to the cave on the moon despite never having been there before, yet she feels otherwise because the evil Moon women are guiding her there.
Déjà Vu: Despite lending the movie its title, this doesn't occur until the end of the film when Denzel Washington's character seems to recall the memories of his temporal duplicate who died just before he showed up.
Along with the more obvious usage throughout the film, Groundhog Day also uses it as the basis for a quick gag:
Rita: "Do you ever have déjà vu?"
Phil: "... Didn't you just ask me that?"
- Also, on his first day in the loop, Phil asks the same question of Mrs. Lancaster, who replies, "No, but I could check with the kitchen".
The Matrix: Neo experiences déjà vu after seeing the same cat go by twice. The rest of the cast go on alert, as déjà vu is a sign of a recent change made in the program, causing A Glitch in the Matrix while the agents patched it.
Top Secret! Our hero is introduces to several members of the French Resistance, one of whom is named Déjà Vu. Naturally he asks if they've met before.

Literature

Alan Alone: When Bai leads the group to a secret room inside the Stylol lab building, Alan realises the place is familiar and says that they aren't quite at the place yet, much to Bai's surprise, and leads them like he suddenly knows more than Bai. Stylol is Alan's father's company, but Alan can't place the familiarity to any specific memory, saying that he has been here before, but not in this world.
Miss Marple: Sleeping Murder starts off with newlyweds Giles and Gwenda Reed buying a house that Gwenda picked out because it feels homely. However, Gwenda, a recent Kiwi immigrant who's never been to England before, finds the house uncannily familiar, and has a flash of seeing a dead body in the foyer from the top of the stairs. After a talk with Miss Marple, she and Giles realize this is because she actually has been to England before, as a small child, and lived in that house... where she witnessed a murder.
The children of A Series of Unfortunate Events experience this in the ninth book, having been forced in front of a large crowd like in the previous two books. The Lemony Narrator goes on to explain the concept of Dejá Vu on three separate occasions in the one book.
- In the eleventh book, we get a recursive description of the water cycle repeated for several paragraphs before the narrator slips in a letter to Beatrice, hoping that the previous tedious narrative caused readers to skip further or stop reading.

Live-Action TV

On Fringe, Walter claims that déjà vu is the result of alternate universes: it happens when an alternate version of yourself has been in the same situation as you are now in.
A Monty Python's Flying Circus sketch involves a show exploring the concept of déjà vu. Suddenly the sketch starts over, and by the third time it happens the commentator starts to notice something is wrong.
On episode 3x01 of Only Connect, one of the categories in the final round is "French phrases used in English." Déjà vu is the both the first and the last answer in the category.
Star Trek: The Next Generation: In "Cause And Effect", the crew are caught in a "Groundhog Day" Loop, Doctor Crusher begins to experience Déjà Vu and so do the other crew members when she brings up the issue. The feeling gets more intense each time they pass through the loop, to the extent that the officers find they know a poker hand before it's been dealt.

Tabletop Games

Last Unicorn Games' Star Trek RPG supplement All Our Yesterdays: The Time Travel Sourcebook. When people are caught in a temporal loop (a "Groundhog Day" Loop where no one remembers that they've gone through it before), they will sometimes get a feeling of déjà vu.

Video Games

BioShock: One of Andrew Ryan's taunts over the radio hints at Jack experiencing this. Rapture is oddly familiar to Jack because he's a Laser Guided Tyke Bomb grown in the city and sent to the surface, programmed to return and kill Ryan.
"So far away from your family, from your friends, from everything you ever loved. But, for some reason you like it here. You feel something you can't quite put your finger on. Think about it for a second and maybe the word will come to you: nostalgia."
In the Marathon Trilogy, in the first game's manual, as the our Hero escapes into the escape pod he ponders this: "Oddly, this is familiar to you, as if it were from an old dream, but you can't exactly remember...". Not much comes of it until the third game, where the plot is centered around saving the reality from getting eaten by a Cosmic Horror, and it involves dream-themed dimension jumping/time-travelling trying to prevent the release of said Cosmic Horror.
Max Payne: Max experiences this in the original game—while having a bad Valkyr trip. In his hallucinations, he enters a room with a ringing telephone. When he picks up, he hears only gibberish and puts it down. However, the next room he enters looks exactly the same, and the voice on the phone tries to tell him he has been drugged—to which he declares that he only hears gibberish and puts the phone down.
Metal Gear Solid V: Ground Zeroes features a DLC episode named after the concept which is formed by a series of Call Backs to the original Metal Gear Solid, even allowing you to play as the protagonist of that game.
In Penumbra: Black Plague, feelings of déjà vu are one of the early symptoms of infection by the Tuurngait virus. The first time you learn this, this particular bit of info is repeated twice, presumably to unnerve the player. And it's fitting, as the player character is already infected.
In Undertale, characters have déjà vu-like memories of the events that happened before the player reloaded the game. Except for Flowey, who can fully remember them. Sans has learned that someone is messing with the timeline using SAVEs simply by being very perceptive.

Webcomics

In Homestuck, this is a telltale symptom of entering a Dreambubble. The sense of Dejá Vu only increases until the dreamer realizes that they're merely recalling a memory.

Western Animation

The Batman: In the episode "Seconds," Batman faces off against Francis Grey, a recently paroled convict who can turn back time. Batman begins experiencing Déjà Vu every time Grey resets the timeline, which allows him to eventually predict what Grey will say and do.
Brandy & Mr. Whiskers discussed a situation that the rabbit had experienced before in a video game, but he is unable to know the term of it, much to the dog's annoyance.
In Danny Phantom, this occurs during Danny's fight with Clockwork.
Danny: I'm going ghost!
Clockwork: Time-Stop. [rewinds Danny]
Danny: I'm going ghost! [Beat] Whoa... serious déjà vu.
Garfield and Friends, both U.S. Acres:
- "Orson's Diner" had a gag where Orson kept taking out and putting away a book on Déjà Vu he found on his bookshelf.
- "Déjà Vu" was all about this, revolving around Orson, Roy, Wade and The Weasel reliving the same scene over and over.
The The Grim Adventures of Billy & Mandy episode "Test of Time" has Grim give Billy a remote control to travel back in time. Billy uses it on Mandy several times before the latter proclaims this trope.
In an episode of The Adventures of Jimmy Neutron, Boy Genius, after managing to get back from the dinosaur era, a baby t-rex that was brought back presses Jimmy's time remote that causes a Reset Button back to the start of the episode, ending with Jimmy saying déjà vu.
Molly of Denali: Grandpa Nat experiences this in "Grandpa's Drum." When Molly and Tooey sing and drum together, he starts seeing visions of himself and his old friend when they were younger, doing the exact same thing.
In Steven Universe, after Steven has another dream about Pink Diamond, Blue Diamond arrives and says the same words she said during the dream, making Steven mutter "déjà blue."