A pair of twins are introduced. They are portrayed as being sufficiently alike that even people who have known them for a long time have trouble telling them apart. Often they serve as comic relief, enjoying the confusion they might cause just as much as the audience. It is highly likely that one twin, and only one, will be killed off. Why?
- Since the twins are alike, less is lost to the story than if a different character is lost.
- If the character is being played by the same actor, it's a great opportunity to do a death scene and yet continue essentially the same role with character development, without Flanderizing a 'serious drama' into Death Is Cheap territory.
- It provides an opportunity to create angst, sorrow, anger, etc. into the character of the surviving twin. The surviving twin may even go from a character who never takes anything seriously to a genuine Action Hero.
In Backup Twin, a character is introduced and later killed off. Only after their death is it revealed they had a Backup Twin, who carries on in the deceased character's place as if nothing had happened. The original twin is often never mentioned again once the new twin explains that he is a twin (or clone, if science fiction) and not the original character brought back to life.
In this trope, either the twins are introduced at the same time or close to it, or else the surviving twin is introduced first, and the dead twin is then introduced in a flashback. The death of the twin must have a profound or at least significant effect on the survivor for it to be this trope. The victim doesn't always have to be an identical twin, provided they play that role.
If the death of the twin occurred after the birth of both children or at early age, because of religion, superstition or popular beliefs, then it's One Twin Must Die.
This being a Death Trope, there be spoilers.
- Kate Kane, the Post-Crisis Batwoman, lost her twin sister Beth and her mother in a terrorist attack when she was 12 years old. Or so she thought, since her first major villain, Alice, turned out be Beth, who was heavily implied to have undergone some serious Mind Rape.
- Pre-2011 Lady Shiva. She and her twin sister Carolyn were excellent martial artists, which drew the attention of David Cain. Cain was looking for the perfect mother to bear a child whom he could mold into the ultimate assassin. He noticed that Shiva and her sister would always hold back against each other to avoid really hurting each other whenever they sparred. David then murdered Carolyn so nothing would hold back Shiva anymore. Years later, Lady Shiva would admit to her daughter Cassandra that she misses Carolyn every day.
- Fray: Though they aren't identical, Mel angsts over accidentally getting her brother Harth munched by Icarus while out on a grab. It gets worse when he's revealed as the Big Bad.
- In Superman storyline Starfire's Revenge, the titular crimelord kills her minion Derek Marlowe when he outlives his usefulness, and then she feeds his twin brother Rodney the lie that Supergirl killed Derek, sending Rodney into a murderous, grieving rage.
- Avengers: Age of Ultron: Wanda Maximoff loses her twin brother Pietro to Ultron, and his death is a very sore subject for her to the point that she refuses to talk about it with anyone other than her future lover, and Monica Rambeau bringing it up in WandaVision is enough to warrant Wanda booting her out of the Hex.
- In Constantine (2005), twin sisters Angela and Isabelle had the powers to see angels and demons. Angela denied her gift, while Isabelle accepted it — Angela became a successful police officer while Isabelle ended up in an asylum, eventually killing herself and thus kicking off the plot.
- Dead Ringers: At the end, Beverly kills his brother with surgical tools at the latter's request in a drug-fueled stupor. He doesn't outlive his brother for long, as he simply can't bear to live without him and instead chooses to die with Elliot.
- The plot of I Miss You, I Miss You centers on this trope, following 14-year-old Tina, whose identical twin Cilla is killed in a car accident.
- Takako in One Missed Call 2. Her twin sister answered the death call and died just days later when they were children. This fueled her decision to become a detective and be able to end the curse.
- In Ophelia, Mechtild ends up outliving her twin sister Gertrude and holds her as she dies. She's clearly devastated, regretting that they never reconciled and that she in-directly caused Gertrude's death (especially as it was one of Mechtild's poisons Gertrude used to take her own life). The last we see of Mechtild is her tearfully embracing her dead twin, now truly alone in the world.
- At the beginning of The Pretty One, the audience is introduced to Laurel and Audrey, identical twins who are otherwise polar opposites. When Audrey dies in a car accident, Laurel tries to pick up Audrey's life, but is hampered by the fact that she's still grieving for Audrey, who in her mind is the more successful of the two, and can't express it to anyone except the support group.
- Prom Night (1980): The killer is revealed to be Kim's younger brother Alex. Alex's twin Robin was killed at the beginning of the film and Alex drove himself to murder the children who killed her.
- Hedy in Single White Female is revealed to be this, both in the story she tells Allie (that her twin was stillborn) and in what we learn really happened. She drowned when they were seven, and the guilt-ridden and lonely Hedy has been searching for a replacement ever since, hence her mimicking Allie's style and appearance.
- In the Star Wars franchise:
- Star Wars: Clone Wars, since every clone with character development is potentially one of these.
- In Star Wars: Episode II — Attack of the Clones, Padmé's lookalike handmaiden Cordé.
- In Star Wars: Episode VIII — The Last Jedi, Rose Tico is introduced mourning the death of her twin sister. After Luke's death in the climax, Leia becomes an angsty surviving twin.
- In Sisters (1973), Danielle developed her violent "Dominique" personality after her Conjoined Twins sister's death from Dr. Breton's separating them through surgery.
- Evillious Chronicles: It takes the sacrifice and death of Allen, Riliane's twin brother and the one person who truly loved her, for Riliane to finally realize (and tearfully regret) her tyranny as a queen and the unforgivable atrocities she had once committed. mothy , being Mothy, is aware of the impact of this trope to the fandom and subsequent materials continue to milk the improbability of Allen ever seeing Riliane again for all the feels it's worth.
- The song "Run For Your Life" by The Fray is about a girl whose twin sister has died; the singer tries to convince her not to give up on life afterward.
- Taako from The Adventure Zone: Balance had a twin sister named Lup. After realizing what the Phoenix Fire Gauntlet (which she made) did to the world, Lup tried to lock it away, but was murdered in the process, and her lich-form absorbed by the Umbrastaff. Taako and Barry searched for weeks, until they had their memory erased by Lucretia, who fed their history to the Voidfish, including Taako's memories of Lup. After regaining his memory, he hits the Despair Event Horizon hard, threatening to murder Lucretia in cold blood, and becoming completely apathetic to the world around him.
Taako: You fucking took everything from me!
- Juno Steel of The Penumbra Podcast had a twin brother named Benzaiten; growing up, the two were nearly inseparable. Then their mother murdered Benzaiten when he was nineteen because she thought he was Juno. Juno's been crippled with guilt over it ever since (both over not having been there to stop it and over the inciting incident that made their mother despise Juno, despite the fact that the latter happened when Juno was four years old), and it's one of the main reasons for his depression and Death Seeker tendencies at the beginning of the series.
- In The Dark Eye this is the fate of all geodes (dwarven mages). Male dwarves are always born as twins, and if one sibling dies before the adulthood ritual (that coincidentially extinguishes all traces of magic potential), the surviving one is given to a hermit geode to help him live with the loss and, in rare cases, become his apprentice. It is expected to make the loss and the search for the wandering soul of the twin a central part of the character in some form.
- In The Strange Case of Dr. Jekyll and Mr. Hyde, Helen's twin sister died the year before the play's events, leaving her feeling as if half of herself had died. She has a mark on her neck that appeared after her sister's death, which is suggested to be a psychosomatic expression of her grief.
- Subverted in Twelfth Night, which opens with Viola having washed up from a shipwreck that she assumes claimed the life of her Half Identical Twin Sebastian. After angsting for a bit, she disguises herself as a boy, very similar to him, which causes all sorts of confusion when he turns out not to be dead at all.
- In Da Capo II Plus Communication, Akane had a twin named Ai who died before the main storyline began. In her grief, she made a wish on the sakura tree to revive Ai, which ended up with her sharing her body with Ai's spirit. When the sakura tree gets withered, the wish is cancelled.
- This sometimes happens to Shion and Mion in Higurashi: When They Cry.
- The Player Character of the otome game Shall We Date?: Ninja Shadow is Saori, a Bifauxnen Action Survivor whose girly-looking twin brother Kaname was murdered in front of her in the game's Downer Beginning. She takes up his place in a Vigilante Man group he was supposed to join to both help their village and avenge his death, with her levels of inner angst depending heavily on which romance route the player chooses for her.
- In SHUFFLE!, Lisianthus had a twin named Kikyou who died before childbirth. As a result, Sia made a pact with Kikyou and ends up hosting her spirit within her body, giving her a Split Personality. In Sia's route, this is a major plot point.
- Itsuki, from Suika. But not really. She was Dead All Along and her sister was in coma, making Sayo the true example, though she doesn't angst much.
- In Drowtales, the ruling Sharen clan has an odd tradition of "hiring" (purchasing) infants of lowly birth as "protector twins" so their own children can know the experience of having a twin. Perhaps not surprisingly, the life expectancy of a protector twin is often relatively short, as the two usually end up in conflict that leaves one of them dead. Which is how it usually goes for other drow twins as well.
- As of chapter 46, Kau, Sil'lice's son, has become this thanks to the death of his natural twin sister Shala.
- In Muted Camille lost her twin sister Chloe and her mother in a fire when she was a child and was left both physically and emotionally scarred in the aftermath.
- Unsounded: Sara and Ilya both die during the attack on the shrine, leaving their sisters befret. Ilya's twin is shown curled up bawling and Siya is shown crying and lashing out in her grief.
- In The Adventure Zone: Balance, Taako is an angsty surviving twin, although the situation is complicated by Lucretia using the Voidfish to erase the others' memories of Lup.
- Dimension 20: In "A Crown of Candy", Ruby becomes one after Jet is killed.
- In Lovers Oath, Bevel is shown to be one of these, though... He doesn't realize his twin is still alive. The twin doesn't know Bevel's alive either.
- In the Red vs. Blue mini-series "Recovery One", Agent South is introduced as one of these, with her brother North having died just as we meet her. It turns out that she
killed himput him in a position to be killed, showing her to be angsty from the get go.
- One of the antagonists of RWBY, Hazel, despises Ozpin due to blaming him for the death of his twin sister, Gretchen.
- DuckTales (2017): After the disappearance of his twin sister Della, Donald is left raising her kids Huey, Dewey and Louie, and the incident caused Donald to cut ties with Scrooge. In addition, he becomes a overprotective to the boys because of the incident. Subverted in that Della is actually alive, but for a series of complicated reasons the two aren't reunited until the season two finale.
- Gravity Falls: Stanley Pines is one to his brother Stanford, doubly so considering he was (or at least considers himself) responsible for the accident that resulted in Stanford being sent to another dimension. Although he puts on a brave face and appears to be the wacky, money-hungry "Grunkle Stan" for most of the series, there are signs throughout the first season that Stanley was deeply affected by the loss of his twin, and he has in fact spent the last thirty years of his life trying to bring Stanford back (and he's eventually successful).
- In Transformers: Prime, after Skyquake gets killed by the Autobots, his twin Dreadwing comes to Earth to get revenge. Everything else comes second, including his loyalty to Megatron and the Decepticons. This comes to a head when he finds out Starscream was the one responsible and later raised Skyquake as a Terrorcon, which causes him to go on a rampage and attempt to kill Starscream despite Megatron ordering him to stand down. He refuses, and he gets a hole through his spark for it.
- There are a number of support groups and resources for "twinless twins," as this is definitely a truth in television for many.
- June Gibbons (of the notorious arsonist-novelistnote Silent Twins of Wales) subverts this all to heck. In interviews, she misses Jennifer, who died the day they were released from Broadmoor hospital for the criminally insane, but seems cheerful enough.note She explains everything in the 1994 documentary The Silent Twins; Without My Shadow.
- More than that: it's said (and the twins' biographer Marjorie Wallace confirms; this is what the girls told her) the twins had long felt that if one of them died, the other must begin to speak and live a normal life, and as they grew older behind the prison walls they came to believe one of them had to die — and that after much discussion, Jennifer agreed to be the sacrifice so that June could be free and happy. Oh, but it wasn't suicide or murder or anything though. She just died.
- This was what the jury concluded at the inquest; but the twins' family and friends had requested expert witnesses, yet none had been called, nor had medical staff from Broadmoor who had cared for the girls. Jennifer's death was due to massive acute viral myocarditis, which can have many causes. Both girls had been under extreme stress, fearing they would not actually be released from Broadmoor as promised. This combined with the psychiatric drugs Jennifer had been taking could have weakened her heart. However, we will never know for sure. Family and friends don't suspect foul play, but rather neglect on the part of medical staff, and the twins' older sister Greta Gibbons gave interviews in 2017 saying the twins should never have been sentenced to Broadmoor in the first place.
- Elvis Presley and Philip K. Dick both had twin siblings (a brother, Jesse, in Elvis' case; a sister, Jane, in Dick's) who died as infants. How much angst from this influenced either's artistic careers is a question for the biographers and psychologists.
- Lisa Bessette, the twin sister of Lauren Bessette, died along with her younger sister Carolyn and her brother-in-law John F. Kennedy, Jr. in a plane crash.
- Linda Hamilton lost her identical twin sister Leslie Hamilton Gearren in 2020.
- Michael Jackson had twin brothers Marlon and Brandon, the latter of whom died shortly after birth. Upon Michael's death, Marlon asked Michael to give Brandon a hug.
- Among the many new specials trotted out for the 10th anniversary of the 9/11 attacks was a feature on the 46 people who lost their twin in the disaster. Some strong emotions were only to be expected.