A senile or crazy character has the unshakable conviction that a character is someone else they know — a specific and actual person, frequently already dead. The most blatant symptom is calling the person by the wrong name, but other inappropriate actions may ensue.
Hilarity Ensues. Or else a horrific depiction of how far gone this person truly is.
A variation (though somewhat uncommon) is to have the other character not only be alive, but in the same room.
- Ayakashi Triangle: Snegurochka came from a picture book where another character, her grandfather Ded Moroz, looks nearly identical to Matsuri's grandfather Seigen. Rochka immediately assumes Seigen is Ded Moroz despite Matsuri's repeated protests. Matsuri eventually gives up convincing her of the truth because believing they share a grandfather makes Rochka marginally less hostile to him.
- Berserk has Serpico's mother succumb to dementia. Their final encounter is when she no longer recognizes him, believing him to be his father, and has been accused of heresy and witchcraft and Serpico must burn her at the stake.
- In Blazer Drive, this happens to the protagonist when an ill mom mistakes him for her dead son. The protagonist, being an orphan who recently lost his older brother, goes along with it. just before she dies, the mom reveals that she knew he wasn't her son, but because it made the both of them so happy she didn't want the "reunion" to end.
- In Devil May Cry: The Animated Series episode 8, a man named Ernest mistakes Dante for his childhood friend Anthony, and won't believe Dante when he says he's never heard of him.
- Ryousuke's mother in Bokura no Hentai underwent a Sanity Slippage after her daughters death. He pretends to be Yui to soothe her. Ryousuke's status as The Unfavorite combined with her deteriorating mental health causes his mother to mistake him for someone else occasionally. Right before his mother is sent for mental health treatment Ryousuke calls out to her dressed as Yui however due to his voice changing he doesn't recognize him at all. This trope is later subverted with the reveal that she knew it was him the entire time, though she did have genuine mental health issues as well.
- In the Dragon Ball Z special Episode of Bardock, Bardock mistakes Chilled for Frieza.
- In Fruits Basket, Tohru's grandfather calls her Kyouko. Kyouko was the name of Tohru's (dead) mother. He is aware of who she is, he just (in his words) "wants to tie them together", as everyone in his life ultimately ends up leaving him.
- Global Garden is an interesting case in that the girl has latent magical powers that are turning her into a boy to grant her mother's wish without the girl being aware that she is doing it.
- In Hayate the Combat Butler, Isumi's mother (Hatsuho) and grandmother (Kokonoe) think they're going to meet the Sanzenin's new butler (Hayate). Kokonoe sees Hatsuho and immediately thinks that Hatsuho is their butler who just happens to look like her daughter. She then realizes who it is and both wonder where the butler went. Hayate is actually visiting, he is standing off to the side during the conversation.
- Inuyasha: "My name is NOT Kikyo. It's Kagome. KAH. GOH. MAY." (Kikyo is Inu-Yasha's ex-girlfriend, Kagome being her reincarnation.)
- In Kongoh Bancho, Machine Banchou mistakes little Tsukimi for "Dr. Tsukina", whose orders supersede all others, and she unintentionally alters his personality by giving him suggestions on how to be cooler. This is played for Nightmare Fuel when she realizes the one thing she can't make him do is not kill Kongou. Also an unusual case of it, as, being a machine, it is frequently pointed out that Machine Banchou identifies people with speech and retina recognition devices instead of, you know, looking at them.
- In an early episode of Pokémon, a random woman mistakes Ash for her missing son and calls him "Arnold."
- Something similar to this happened in Secret Plot Deep, where the main male character's twin sister died in an accident, and his parents were so shaken up about it that they started believing he was his sister. Apparently, they got rid of all the photos of him and forgot he existed. To keep them content, he cross-dressed when at home. This leads to transvestite sex with a girl from school. And a female teacher.
- In Star Blazers, Queen Starsha initially mistakes Nova for her own sister Astra, who died in the first episode. (She's not the only one to notice the resemblance, which is very strong, but unexplained.)
- Played for Drama in Tokyo Magnitude 8.0 where an older woman mistakes Mirai and Yuuki for her two grandchildren who died in an earthquake the previous day.
- JLA: The Queen of Fables, an evil sorceress from a story book believes that Wonder Woman is her arch enemy, Snow White. No matter what evidence is presented to her, she refuses to believe otherwise, and seems completely unaware of the passage of time, as the real Snow White lived and died centuries ago. She also mistakes Superman for Prince Charming.
- The League of Extraordinary Gentlemen has what appears to be an explicit tribute to Only Fools and Horses by not only using this trope, but also reusing the name "Dave".
- At one point in Suicide Squad, a mentally-unstable Deadshot starts seeing his boss Amanda Waller, his team leader Rick Flag, and a senator Flag wants dead as his mother, his brother, and his father respectively. He relives his worst memory through them and gets it "right" this time... which involves shooting his "father" before his "brother" can do it himself. Deadshot's family history is pretty screwed up.
- Enrico La Talpa, from the Italian comic strip Lupoc Alberto, has addressed the eponymous protagonist as "Beppe" ever since his first appearance. As years went by, Alberto went from his initial bemusement to desperate frustration and eventually to wry resignation. The real "Beppe" (supposedly a friend of Enrico's) has never actually appeared in the strip, while Enrico eventually admitted he now knows that Alberto isn't Beppe, he's just using it as a nickname.
- Effie in the Ernie/Piranha Club newspaper comic regularly mistakes people for one of her many ex-husbands. (Except Arnold, which she thinks is one of her old dogs.)
- Bitter Repercussions: Mistaken identity caused the elderly Graypool to accidentally reveal to Tigerstar that two RiverClan warriors were ThunderClan-born. She mistook him for the deceased-but-similarly-looking Oakheart. Graypool realized her error too late.
- Several Harry Potter fics have Luna, her father or both firmly convinced that Sirius is "really" Stubby Boardman of the Hobgoblins. In In This World and the Next he admitted having used his resemblance to the latter to pick up women.
- In NoHoper when Neferet assumes Light has been possessed by Kalona, her lover and the Big Bad. Light has no clue what's going on but for the sake of self-preservation plays along with it.
- In Turnabout Storm it happens to Phoenix twice while in Equestria. First he confuses Sonata with his deceased mentor Mia, something that happens because both have the same voice, and since Sonata looks exactly like Mia would look in pony form. Later on, and more amusingly, he confuses Applejack with Lotta Hart because of the accent, making him completely freak out.
- In *batteries not included, the elderly and possibly senile Faye persists in addressing one of the other characters by the name of her (dead) son. And in a heartbreaking scene in the end, when said character decides to play along for once and pretends that he is her son (because he set the house to blow up, and is trying to save her) by showing her his "new car", it causes her to break through her denial and realize the horrible truth....
- Seymour in The Cannonball Run spends the whole movie pretending he's Roger Moore in-character, not just played by him. This allows him to pick up a whole series of women... at least, until one of them reveals that she joined him in his car because thinks he's George Hamilton. (No dementia involved, the woman is evidently just a Brainless Beauty.)
- In The Dry, Mal Deacon, who is going senile, keeps thinking that Aaron Falk is actually his father Eric Falk, who hasn't lived in the town for 20 years.
- Four Weddings and a Funeral plays with this trope:
Charles: How do you do — my name is Charles.
Old Madman: Don't be ridiculous, Charles died twenty years ago.
Charles: Must be a different Charles, I think.
Old Madman: Are you telling me I don't know my own brother?
- In Mars Attacks!, senile old Grandma Norris calls both of her grandsons "Thomas". Strangely enough, she does remember their names in some capacity, as she tells Ritchie that "Ritchie" was always her favorite... while still calling him Thomas.
- In the western Quigley Down Under, Crazy Cora keeps calling Matthew Quigley 'Roy'. (Roy turns out to be Crazy Cora's first husband, who left her after she accidentally killed their child.) Which is what made it so significant when she called him by his full name in the final moments of the film.
- In Serial Killing 4 Dummys, Rose, who is going senile, is convinced that Casey is her grandson Charlie, and Casey winds up being forced to play along with the delusion.
- In the Madonna/Sean Penn movie Shanghai Surprise, when Penn's character, Glendon, goes to a fancy restaurant he's mistaken by all and sundry for another character named Phil — who is never mentioned before or after this scene, nor is Glendon's resemblance. Nonetheless, the fact that Glendon looks like and is mistaken for Phil is a vital plot point without which the movie makes no sense (it's the reason Glendon was picked for the mission, it's how he gets an entree with a lady named China Doll, etc.).
- In the final scene of Smoke, Augie poses as a blind old lady's grandson rather than let her spend Christmas alone. Subverted in that she probably realizes that he isn't actually her grandson but goes along with the act rather than admit that she has been abandoned.
- The film Spider is told from the perspective of its protagonist, a paranoid schizophrenic who has been released from a mental hospital. We see him reliving his childhood where it's revealed that he killed a woman who he was convinced had replaced his mother, who murdered her in conjunction with his father. He is, of course, wrong.
- There's an old Yiddish joke set in Chelm, the legendary city of fools. It ends:
"You know, I don't know how I ever recognized you. Yankel, what has become of you?"
"I've been trying to tell you. I'm not Yankel."
"Oy, you've gone and changed your name as well!"
- A drunk goes up to a lady in a bar, thinking she looks just like his wife. After rebuffing him with increasing rudeness, the drunk comments that not only does she look like his wife, she sounds just like her too.
- The Animals of Farthing Wood. After Mole dies, Badger is pretty old and out of it by this time, so when he encounters Mole's son, Mossy, he mistakenly believes that Mossy is his father. Weasel, wanting to be kind to Badger in his last few years, asks Mossy to keep up the charade to spare his feelings.
- In Big Trouble, after Arthur accidentally crashes into Enemy Toad and its hallucinogenic eye glands, he starts raving wildly under the impression that Roger is a demonic form of Elizabeth Dole, impervious to the fact that Roger is a dog.
- In Choke, the protagonist's mother spends most of the book confusing him for someone else, and one of her fellow patients in the nursing home is convinced that he is her brother who molested her as a child.
- Terry Pratchett's Discworld:
- In Feet of Clay, Old Mrs Gammage has been going to the same pub for decades. Now deaf, blind and senile, she's completely failed to realize it's become an undead hangout. The "monsters" are too nice to tell her the truth, so when we see her she's cheerfully calling a bogeyman "Charlie", and asking about his plumbing business.
- In A Hat Full of Sky, old Mr. Weavall keeps calling Tiffany "Mary" after his daughter, who died years ago. He eventually wises up, though, hinting his use of this trope is less senility and more wishful thinking.
- Played initially for somewhat tension-filled humor, then for tragedy in the first Dragonlance novel, Dragons of Autumn Twilight. The children of the very much human captives/slaves at Pax Tharkas are being used as hostages for their good behavior and "guarded" by an ancient, notionally "evil" but in reality very much senile dragoness who has come to think of them as her children (whom she lost centuries ago when she couldn't convince them to stay out of the war going on at the time). It ultimately leads to her Heroic Sacrifice when the slaves' escape attempt is discovered and the local evil overlord announces his intent to kill them all.
- A woman named Bertha mistook Ephraim Kishon for the guy who made the drawings her dead husband liked so much, in the weekly newspaper he read. Kishon wrote for a daily, non-illustrated newspaper. That is, in the story. It tends to overlap.
- Caster of Fate/Zero, Gille de Rais, cannot be convinced that Saber isn't Joan of Arc. Also counts as something of a Fandom Nod since that's often readers' first guess as to her true identity too.
- The Five Find-Outers (well, minus Fatty) once mistook Ernest Goon for Fatty, thinking he was in a clever disguise, and his repeated claims that he didn't know them and wasn't their friend just was a part of the disguise.
- In Dan Abnett's Warhammer 40,000 Gaunt's Ghosts novel Straight Silver, some Ghosts find an old woman in the woods, and a deserter that she apparently thinks is her son.
- Professor Binns in Harry Potter is constantly mistaking everyone for the students of centuries past. It's implied that he's so out of it, he doesn't even realize he died.
- In a Hoka story by Poul Anderson and Gordon R. Dickson, the Hoka Sherlock Holmes persists in calling Alex Jones "Watson" — the real, which is to say Hoka, Watson is not there, and he can't avoid the pattern. This is a particular variation on this trope. The basic premise of the Hoka stories is that the Hokas (a highly intelligent race that just happen to resemble teddy bears) have trouble distinguishing fact from fiction, so whenever they come across a human novel they end up acting it out and Hilarity Ensues. It's never entirely clear when they do so whether they are conscious of the fact that it's just a re-enactment.
- In Hero Years, I'm Dead features a poignant take on the trope. An old, long-since retired hero— once one of the greats— takes the protagonist for his oldtime archnemesis. Unusually, he's quite friendly despite this— the protagonist's behavior gives him the impression that said archnemesis has reformed. When he is killed in an ensuing supervillain attack, his last words are to his supposed archnemesis, "Be Good." The protagonist agrees on his behalf. It later turns out that there's even more to this— the mistaken identity was because the protagonist looks just like his supervillain father, and his agreement to "Be Good" is deeply meaningful to him because the elder hero turned him from his father's path with that injunction.
- In Vivian van Velde's Now You See It, the main character's senile grandmother keeps calling her by the wrong name. It turns out this is because the main character traveled back in time and befriended her grandmother; her grandmother is calling her by the false name she gave.
- In Angie Sage's Septimus Heap books, several ghosts always call Jenna Esmeralda. In Physik, she ends up in Esmeralda's time and everyone takes her for her.
- In Madeleine L'Engle's A Swiftly Tilting Planet, Mrs. O'Keefe calls Charles Wallace "Chuck." She turns out to be confusing him with her long dead brother.
- ...who Charles Wallace technically was. Sort of. It's that kind of book.
- In Edgar Rice Burroughs's Swords of Mars, he meets, while in disguise, a woman named Zanda, who comes from the city of Zodanga, destroyed because of John Carter's actions. She has sworn Revenge if she ever meets him. She therefore deliberately feigns this trope when she realizes the truth.
"I am very happy, Vandor," she replied, "happier than I ever expected to be in my life."
She emphasized the word Vandor, and I thought that I detected a smile lurking deep in her eyes.
"Is your happiness so great," I asked, "that it has caused you to forget your vow to kill John Carter?"
She returned my bantering smile as she replied. "I do not know anyone by the name of John Carter."
- In the X-Wing Series a particularly old and addled man at a museum confuses Lara Notsil for someone else he once knew. In typical Star Wars fashion, he actually confused her for her mother, an Imperial Intelligence agent, like Lara/Gara/whatever-her-name-is-today herself. This confusion puts another Wraith on the trail to discovering her identity, no less. Initially made extremely funny, before the dramatic fallout happens later, by Face afterward pretending to 'recognize' her too, using increasingly-ridiculous names.
- In the Angel episode "Damage", Dana is both mentally unstable and experiencing the collective memories of the previous Slayers, so she mistakes Spike for the man who murdered her family and tortured her, even though Spike doesn't look anything like him (the man was fat, ugly, and had black hair, while Spike is slim, handsome, and blond), and seeks revenge. Spike eventually convinces her she has the wrong guy, but she decides to kill him anyway for the crimes he is guilty of before Angel rescues him.
- Invoked in As the World Turns by Paul Ryan in order to distract Dusty. He hires a woman named Josie who bears a striking resemblance to Jennifer, his sister and Dusty's recently deceased wife. After getting to know her, Dusty begins to believe that Josie has a connection to Jennifer rather than thinking she is really her, as Josie is pretending to have amnesia and "remembers" former events that actually happened to Jennifer.
- The third season's finale of Buffy the Vampire Slayer, "Graduation Day Part Two", has Willow watching over a poisoned and delirious Angel. Delirious, he mistakes her for Buffy and confesses how much he needs and loves her. She then leaves the room and tells Oz that he had thought she was Buffy. He replies "You too, huh?"
- An episode of CSI: NY drew upon a story from Real Life below. Two girls were in an auto accident. One was killed, while the other survived, albeit badly injured. However, the survivor was later murdered in the hospital. It turns out her killer was her own mother, who, like everyone else, believed her identity to be that of the other girl, whom she blamed for the accident. Her mother kills her in a misguided act of revenge, believing her to be someone else.
- EastEnders: In an episode aired on 18th July 2016, Ian gets a phone call from the hospital to say his half-brother, Ben has been involved in a fight and is in a critical condition. At the hospital, Ian and Phil are told by a doctor that Ben has died. Phil sort of breaks down, leading to Phil and Ian identifying "Ben's" body. In a shock twist, it turns out to be Paul's body, Ben's boyfriend. Phil and Ian come out of the morgue, with Phil yelling "that ain't my son!" Later, it's revealed by Ben that Paul and Ben got their coats and phones mixed up when coming out of a night club in Soho.
- Get Krack!n: In the final episode of season 2, Indigenous actress (and temporary host) Miranda Tapsell is continually mistaken for being Deborah Mailman (a completely different Indigenous actress).
- Grey's Anatomy has Meredith's mother, who has Alzheimer's Dementia, mistake George for her ex-husband Thatcher. She also believed Meredith was still a child, so she didn't recognize her when she saw her.
- Averted or inverted in one episode of Highlander: The Series, a slightly senile old lady is sure that Duncan is her old lover. Her handler convinces her she is mistaken, as he's far too young. She later convinces herself that he must be her lover's grandson, and he doesn't undeceive her until she's about to die.
- This was also used as the basis of an episode of House where the doctors' efforts simply made the patient worse. It turned out, of course, that they were basing the treatment on the wrong medical records.
- In one episode of Justified, Arlo mistakenly calls Boyd "Raylan." This is used to show that the elderly Arlo's mind is slipping as Boyd and Raylan are Bizarro-like foils in the series. Raylan, Arlo's estranged, biological son, is a U.S. Marshal. Boyd, who Arlo treats like a son, is a career criminal and a series-long antagonist for Raylan.
- One episode of Lie to Me has Cal Lightman meeting a woman with Alzheimer's Disease who mistakes him for her (dead) husband, and insists that someone murdered her (also dead) sister. They eventually realize that she has attributed mistaken identities to virtually everyone in her life, and the fellow nursing home patient she'd confused with her sister was the victim of an Angel Of Death style Serial Killer. She'd witnessed the murder and had been struggling desperately through most of the show to remember it.
- Midnight Caller: In "Old Friends", one old man is convinced that it's 1945, and Jack is his friend Duncan Ingleheart who was wounded in Normandy.
- An episode of Nash Bridges had this happen when Cassidy and her friend Angela got into a car accident. A doctor later tells Nash that Cassidy has died. After some despair, it's revealed that the girls' identities were mixed up and it was actually Angela that died. Despite the similarity to the case of Whitney Cerek and Laura Van Ryn below, the episode actually predates that incident.
- In one episode of NCIS a homeless woman convinces herself that DiNozzo Sr is her father. Over the course of the episode it gets revealed that the woman's father is long dead, and that the woman herself is suffering dementia as a result of a inoperable malignant brain tumor. At the end of the episode Sr walks into the hospital room that she's likely to die in in the very near future and plays along with her delusion so she could die believing that she'd finally reconciled with the father she hadn't spoken to in over a decade.
- Raising Hope has Cloris Leachman as Maw Maw, who thinks her great-grandson Jimmy is her dead husband. Traumatizing Frenching and ass-slapping ensue.
- There's an episode of Stargate SG-1 where Merlin repeatedly refers to the team and a few other characters present by the names of people he knew. He calls Mitchell "Percival", Jackson "Galahad", Carter "Guinevere" and Ba'al "Mordred".
- Star Trek: Voyager: In "Resistance", an old man named Caylem thinks that Janeway is his daughter Ralkana, even though she lacks his species' features. It is later revealed that his wife and daughter are dead; his wife died in prison twelve years ago and his daughter died when they attempted to rescue her and Caylem ran away in fear. When Caylem is mortally wounded, Janeway pretends to be Ralkana and assures him that his wife is safe and forgave him for abandoning her.
- The Twilight Zone (1985): In "The Once and Future King", Elvis Presley mistakes Gary Pitkin, an Elvis Impersonator from 1986 who looks just like him, for his stillborn identical twin brother Jesse who has come Back from the Dead. Gary allows him to believe this and tries to use the opportunity to convince Elvis that he has a very bright future ahead of him. It doesn't go according to plan.
- Within Temptation's song "Say My Name" is about someone with Alzheimer's.
Please, say my name
Remember who I am
You will find me in the world of yesterday
You drift away again, too far from where I am
When you ask me who I am.
- In the French satirical puppet show Les Guignols de l'Info, Liliane Bettencourt (one of France's richest women) is portrayed as quite senile (and nicknamed "Mamie Zinzin"), and is always confusing Nicolas Sarkozy for someone else, like the General de Gaulle or Jacques Cousteau.
- One episode of Spitting Image had Ronald Reagan meeting Mikhail Gorbachev, but failing to recognize him, causing him to wonder what kept Leonid Brezhnev so long?
- In Bendy and the Ink Machine Chapter 4, Henry Stein meets Bertrum Piedmont, a one-time big shot engineer that Joey Drew hired to build an amusement park based off his studio's cartoons. Bertrum worked with Joey at least long enough to be insulted when Joey called him "Bertie" in front of people from Wall Street, to build several attractions for the park (one of which he personally had been working on for at least a month), and to harbor a grudge against Joey over the way things ended. Yet on meeting Henry, Bertrum addresses him as "Mister Drew" in the middle of a combination Badass Boast and "The Reason You Suck" Speech and attacks him to get revenge. (Insanity is the most reasonable explanation: we don't know if Henry resembles Joey, but Bertrum was the only one to mix the two up. Besides which, we also know that, unlike Joey, Henry doesn't use a wheelchair.)
- Bloodborne has the old woman, assuming you sent her to Oedon Chapel. As the night progresses, she'll start taking sedatives. They keep her (somewhat) sane, but will take her toll on her wits, to the point where she assumes the Good Hunter is her child. On one hand, this does cause her to give them sedatives, which are a useful resource. On the other, she'll soon run out and go out to find more, with predictable results.
- Dark Souls: Absolutely heartbreakingly done with The Fair Lady. She is completely blind, in massive amounts of pain, and the only person who even speaks her language is her sister, Quelaag. The player can understand her using the Old Witch's Ring, but you are a Heroic Mime and can't talk back, so she therefore assumes that you must be Quelaag. Unfortunately, Quelaag is dead. Because she jumped you as soon as you came anywhere near her, forcing you to save your own life by cutting her down, and you have to go through her arena in order to meet the Fair Lady in the first place.
- Dragon Quest IX gives us the Wight Knight, who thinks that a princess is his lover from many years ago. Said knight has been dead for god knows how long, and only recently had been raised. His lover, and even his hometown, has been dead for a very long time — but the princess eventually plays along after hearing his plight, allowing his spirit to rest in peace.
- The above Fate/Zero example comes up again in Fate/Grand Order. Gilles de Rais and a few other characters (all of whom are violently insane) will autonomously prioritize attacking Saber-face characters in combat, apparently due to being fixated on a certain Saber-face and unable to tell them apart.
- Under a different definition of senility, 343 Guilty Spark in the first game, Halo: Combat Evolved, doesn't seem to see a difference between Master Chief and his long-extinct creators, talking to Master Chief as if they've met before and referring to past conversations they've never had. The matter of who his creators are is one of the first hints of many indicating a connection between them and humanity.
- Halo: Silentium expands on this a bit by implying that Guilty Spark was, for whatever reason, under the momentary impression that the Chief was his actual creator, the IsoDidact, whom Guilty Spark hasn't seen in about 100,000 years.
- In The Legend of Zelda: Majora's Mask, Anju's grandmother mistakes Link for her son, Anju's dead father. Mistaking Link might be a genuine accident, but she definitely uses this to trick her daughter into thinking she's senile as Anju is a terrible cook.
- In Neverwinter Nights, the player is mistaken for the Teller Of Places's dead lover, until the player is able to convince her that she is wrong.
- Not quite a character, but in Tales of Symphonia, when you meet Raine's and Genis's mother, the poor woman has deluded herself into thinking that she's still pregnant with Genis and carries around a doll that she treats as baby Raine. When the real Raine and Genis appear, she refuses to believe they're who they say they are, and she orders them out of the house. What makes her especially deluded is that given the difference in her two children's ages, Raine would've been ten or eleven when their mother was still pregnant with Genis.
- [PROTOTYPE]: the protagonist believes he's Alex Mercer, suffering from The Corruption. He's not; he's a strain of The Virus, unconsciously mimicking its first meal.
- The Desert Princess stage from Shantae has the senile adviser mistake Shantae (And then Sky, Risky Boots and Rottytops), all svelte attractive women (Not to mention the last two are purple and a zombie) for the rotund, fish-faced actual princess. According to her, this happens a lot.
- Street Fighter's Rufus does this so often that it's practically a character trait. He mistakes anyone blond or wearing a gi for his assumed nemesis Ken Masters, who is both blond and wears a gi. If the character's female, Rufus simply assumes Ken is cross-dressing or somehow making himself look smaller to fool him.
- In Undertale, from the True Lab onward, Asriel refers to you as whatever you named the fallen human as — which turns out to not be the player character's name, but actually the name of the original Fallen Child that Asriel befriended long ago. Asriel is projecting them onto you in a desperate attempt to not have to say goodbye again. He eventually realizes that you're not his old friend, but only after beating you to a billionth of a hit point in a desperate bid to kill you and make you reset so he can keep playing with you.
- In Vampire: The Masquerade Bloodlines, the player is recognized by a friend of theirs from before they were embraced. However, because the player is now an immortal vampire required by vampiric laws to cut themselves off of everyone they knew as a human, they can't let her know it's really them without getting a Masquerade violation. To avoid this, she can be Killed to Uphold the Masquerade, or they can pretend she comes across as this trope to them—thereby convincing her she simply mistook the PC for her missing friend, and causing her to dejectedly apologize and leave without reporting her encounter with the player to anyone.
- In Xenogears, the two main protagonists, Fei and Elly have been reincarnating since the dawn of "history", 10,000 years before the start of the game. As such there are several characters (such as Krelian) who are functionally immortal who knew their previous incarnations. Emerelda was also created by one of their past incarnations as a Replacement Goldfish for the child Elly was incapable of having at that point in history. Emerelda refers to Fei as "Kim" because she actually believes that Fei is Kim and is a legitimate case of this trope in action. Krelian meanwhile knows full well that these are separate people from the ones he was friends with 500 years ago, but calls them Lacan and Sophia anyway because its his way of keeping their memory alive.
- In The 10 Doctors, a group of Renegade Daleks mistake the Sixth Doctor for their ally, "The Keeper". He decides to run with it for the moment. When a Dalek leader demands that he proves his identity, he accuses it of being an undercover Imperial Dalek with a paintjob, and demands that it proves its identity by explaining who "The Keeper" is.
- In No Rest for the Wicked, the witch calls the kidnapped children Hansel and Gretel. They explain that they are really Anna and Klaus. Later revelations show that her own children had been Hansel and Gretel and that she's made the same "mistake" with other pairs of children who didn't get off as lucky as Anna and Klaus.
- When Pibgorn takes Dru as "Sylvia", Dru intervenes, seriously.
- Something*Positive: one of the few male employees of Nerdrotica complains about one of his callers, an older gentleman who consistently calls him by the wrong name and talks as if the two are acquainted in real life; it's assumed that he's senile and is mistaking the employee for someone else. Turns out that the caller is is so lonely that his one solace is calling a phone sex line and having a totally mundane conversation while he pretends the employee is his partner, whom he knows has been dead for years but has never ceased to mourn for.
- In the Adventure Time episode "King Worm," the Ice King addresses Finn and Jake as Fionna and Cake; both a reference to a previous episode and a hint that he's just part of the dream.
- American Dad!: In "The American Dad After School Special", Stan develops anorexia and sees a therapist who believes he's a teenage girl (because, after all, they're the only ones who can be anorexic).
- In Batman: The Animated Series, as Maximilian Zeus becomes more unhinged, he starts referring to Batman as Hades. By the time he's put into Arkham at the end of the episode, he believes it's Olympus and his fellow super-villains are various other Greek gods.
- In the fourth season of BoJack Horseman, BoJack's mother Beatrice has succumbed to dementia and seems to believe that BoJack is a maid named Henrietta. The second-to-last episode of the season, "Time's Arrow", reveals that she and her husband Butterscotch did have a maid named Henrietta, who Butterscotch had an affair with, resulting in the birth of BoJack's long-lost half-sister Hollyhock.
- Professor Farnsworth from Futurama has done this at least once. In the episode "Teenage Mutant Leela's Hurdles", he drives to Florida (he is trying to catch his escaped gargoyle) then stops at a cafeteria (it's implied he had been here before). He walks up to the counter and calls the cashier "Mavis" and says "surprised to see me back so soon" but then the cashier (who's actual named Wanda) explains that "Mavis" had died years ago.
- In The Powerpuff Girls episode "Abracadaver", the zombie of Al Lusion mistakes Blossom for the little girl who accidentally killed him.
- The Simpsons:
- In "The Principal and the Pauper", returning soldier Armin Tamzarian visits Ma Skinner to deliver news of her son, his commander, being taken prisoner by Vietcong. She instead mistakes him for her son and he moves in, eventually becoming a school principal to honor his commander's dream. Judging from her behavior, she actually knows he's not her real son, but puts on the charade anyway. When the real Skinner returns and moves in, she doesn't like him as much.
- In "A Fish Called Selma", Abe visits the DMV and refers to both of Marge's sisters as "Marge".
- South Park:
- Stan's grandfather constantly calls him "Billy". But then again, his grandfather called him Billy when his ghost briefly appeared.
- In "Dances with Smurfs", some idiot murdered the 9-year-old morning announcer after he mistook him for the middle-aged man his wife was cheating on him with.
- This can happen when Alzheimer's and other forms of dementia get too advanced. It can be very hard on the people in question to continually be mistaken for someone else.
- The last time Adolf Hitler visited the old and senile president Paul von Hindenburg the day before Hindenburg died, the latter believed he was Kaiser Wilhelm II. He called Hitler "Your Majesty" when he first walked into the room. The Kaiser (under whom Hindenburg had served as general) had been in exile since the end of World War I. Hitler had just passed a law that would give him absolute power after Hindenburg died. Guess what happened after that?
- When Muhammad Ali visited a nursing home, one man confused him with Joe Louis. When one of Ali's handlers started to protest, Ali insisted on going along with it because it made the man so happy.
- A tragic example in which both identities being dead occurs in the documentary Boy Interrupted: Evan Scott Perry is Driven to Suicide by mental illness, and is laid to rest with his uncle Scott Perry, who was also driven to suicide by mental illness. At the funeral, Scott's mother/Evan's grandmother is wondering why they're having Scott's funeral again.
- In 2006, Taylor University students Whitney Cerak and Laura Van Ryn were among the victims of a severe automobile accident. Whitney survived; Laura did not. Due to the placement of a purse at the crash site, each girl was identified as the other, and the error was only discovered five weeks later when Whitney had sufficiently recovered from her head trauma. (This likely was the inspiration of a House episode with a similar mistaken-identity plot.)
- Charles-Louis Cadet de Gassicourt, Napoleon's pharmacist, was mistaken for Napoleon himself by an Austrian mental patient when he visited the Vienna asylum in 1809.