History Main / SingleLineOfDescent

* The [[UsefulNotes/TheCrusades Kingdom of Jerusalem]] experienced this for four generations of Kings and Queens during the thirteenth century. With the death of the King of Jerusalem [[LastOfHisKind Conradin]], the line of his great-great-grandparents Isabella I and her second husband Conrad of Montferrat became extinct, thanks to their daughter Maria of Montferrat and her descendants only having one surviving child each[[Note]]Maria was likely born after her father’s death, and both her and her daughter Isabella II suffered DeathFromChildbirth. Isabella II did have a child before her son Conrad but the child died in infancy.[[/note]] This caused a succession dispute between two of Conradin’s half-second cousins once removed as the closest living relatives with a claim to Jerusalem.

** The Targaryens tried keeping it [[RoyalInbreeding in the family]] too much, but it's a common knowledge that there are many Targaryen descendants in Westeros, either illegitimate or through the female line. Aegon IV was such [[ReallyGetsAround a gigantic casanova]] that it was said that he had slept with every woman in the Seven Kingdoms, so there are probably hundreds of illegitimate Targaryens lurking about. The Baratheons were actually founded as a cadet branch of the Targaryens, since their founder Orys Baratheon was a bastard son of Aerion Targaryen (father of Aegon I), and Robert, Stannis, and Renly Baratheon additionally have a much recent Targaryen ancestor in the form of their paternal grandmother, Princess Rhaelle (in fact, it's the reason why Robert managed to take the Iron Throne in the first place). They have also married fellow noble houses like the Longwaters, Penroses, Plumms, and Martells, which becomes a plot point in ''Literature/ADanceWithDragons''. Even though the Blackfyres (descended from a legitimized bastard of Aegon IV) are extinct in the male line, the female line is rumored to have survived to the present day, and it's possible that [[spoiler:the supposed "Aegon VI", the long-thought-to-be-dead son of Prince Rhaegar Targaryen, is actually a Blackfyre descendant.]]

** The Targaryens tried keeping it [[RoyalInbreeding in the family]] too much, but it's a common knowledge that there are many Targaryen descendants in Westeros, either illegitimate or through the female line. Aegon IV was such [[ReallyGetsAround a gigantic gigolo]] that it was said that he had slept with every woman in the Seven Kingdoms, so there are probably hundreds of illegitimate Targaryens lurking about. The Baratheons were actually founded as a cadet branch of the Targaryens, since their founder Orys Baratheon was a bastard son of Aerion Targaryen (father of Aegon I), and Robert, Stannis, and Renly Baratheon additionally have a much recent Targaryen ancestor in the form of their paternal grandmother, Princess Rhaelle (in fact, it's the reason why Robert managed to take the Iron Throne in the first place). They have also married fellow noble houses like the Longwaters, Penroses, Plumms, and Martells, which becomes a plot point in ''Literature/ADanceWithDragons''. Even though the Blackfyres (descended from a legitimized bastard of Aegon IV) are extinct in the male line, the female line is rumored to have survived to the present day, and it's possible that [[spoiler:the supposed "Aegon VI", the long-thought-to-be-dead son of Prince Rhaegar Targaryen, is actually a Blackfyre descendant.]]

** The Targaryens tried keeping it [[RoyalInbreeding in the family]] too much, but it's a common knowledge that there are many Targaryen descendants in Westeros, either illegitimate or through the female line. Aegon IV was such [[ReallyGetsAround a gigantic gigolo]] that it was said that he had slept with every woman in the Seven Kingdoms, so there are probably hundreds of illegitimate Targaryens lurking about. The Baratheons were actually founded as a cadet branch of the Targaryens, since their founder Orys Baratheon was a bastard son of Aerion Targaryen (father of Aegon I), and Robert, Stannis, and Renly Baratheon are Targaryens in the female line (in fact, it's the reason why Robert took the Iron Throne in the first place). Targaryens have also married into other houses, like the Longwaters, Penroses, Plumms, and Martells, which becomes a plot point in ''Literature/ADanceWithDragons''. Even though the Blackfyres (descended from a legitimized bastard of Aegon IV) have been declared extinct in the male line, the female line is rumored to have survived to the present day, and it's possible that [[spoiler:the supposed "Aegon VI", the long-thought-to-be-dead son of Prince Rhaegar Targaryen, is actually a Blackfyre descendant.]]

** The Targaryens tried keeping it [[RoyalInbreeding in the family]] too much, and there do seem to be female line descendants, such as the Martells, Plumms, and Penroses, and apparently the Longwaters are illegitimate descendants.

* The [[UsefulNotes/TheCrusades Kingdom of Jerusalem]] experienced this for four generations of Kings and Queens during the thirteenth century. With the death of the King of Jerusalem [[LastOfHisKind Conradin]], the line of his great-great-grandparents Isabella I and her second husband Conrad of Montferrat became extinct, thanks to their daughter Maria of Montferrat and her descendants only having one child each. This caused a succession dispute between two of Conradin’s half-second cousins once removed as the closest living relatives with a claim to Jerusalem.

** The Hapsburgs of Austria and Spain tried [[KissingCousins keeping it in the family]]. The last member of the Spanish line, Charles II, ended up being saddled with a truly depressing array of mental and physical disabilities and was probably sterile to boot, so it's safe to assume they didn't exactly find the winning formula, either; his death led to the UsefulNotes/WarOfTheSpanishSuccession that ultimately led to Spain passing out of Habsburg hands and into those of their rivals, the Bourbons.

** The Targaryens tried keeping it [[IncestIsRelative in the family]] too much, and there do seem to be female line descendants, such as the Martells, Plumms, and Penroses, and apparently the Longwaters are illegitimate descendants.

* ''Radio/TheShadow'', the BigBad is the last descendant of UsefulNotes/GenghisKhan. And now compare this to what is written in the RealLife section.

* In ''{{Fanfic/SPECTRUM}}'', Cadance is the last living descendant of Princess Luna, a line thought to have gone extinct a millennia ago.

* ''Manga/JoJosBizarreAdventure'' is a GenerationalSaga following the descendants of Jonathan Joestar. The first five generations (and three protagonists) are only children. While several of the Joestars only lived long enough to have one child, the second protagonist (Jonathan's grandson Joseph) lived at least into his 80s yet he and his wife ''still'' only had a single daughter. Things get more complicated from then on, as the next two protagonists are a newly-found illegitimate child of Jonathan's grandson and a child of Dio [[GrandTheftMe possessing Johnathan's body]]. Even by the fourth generation, the family name would change, but retain a "Jo" syllable to continue being [=JoJo=].

* When it comes to European royalty, the grand champion of averting this trope might well be Edward I of England (the legendary "Edward Longshanks" of ''Film/{{Braveheart}}'' fame), who lived between 1239 and 1307 and fathered ''sixteen children'', nearly all of whom survived into adulthood and had children themselves. According to genealogists who have studied his family line, the man now has close to four million living descendants around the world (most of them are in the United States, Canada, and Brazil of all places). Apparently all U.S. Presidents except for UsefulNotes/MartinVanBuren are descended from him.

* Discussed during the Chamber of Secrets arc of ''Fanfic/TheOddsWereNeverInMyFavor''. When discussing who could be the Heirs of the Founders, it is mentioned that the Ravenclaw line is definitely extinct (Rowena's only child died childless), the Slytherin line is believed extinct (after the last Gaunt died in Azkaban), and that Gryffindor was a notorious womanizer and that it would probably be easier to name the people in magical Britain who ''aren't'' descended from him somehow.

** Exception: The plot of the cell phone game ''VideoGame/CastlevaniaOrderOfShadows'' involves three Belmont siblings, two of them women. But only the guy gets to take on Dracula, and the game isn't considered canon anyway.

** Played straight during ''The End Times'' scenario when the character [[spoiler:Volkmar the Grim]] is revealed to be the last blood heir of Sigmar, who [[KingInTheMountain disappeared from human lands]] 2500 years earlier. Unlike with the elves, no slow generation time, ancient daemons with a grudge or bloodline breeding programme is involved, and Sigmar was known to have neither married nor sired children, which is why The Empire has an ElectiveMonarchy in the first place.

* Averted in ''Manga/YonaOfTheDawn''. Everyone in the dragon villages is descended from one of the Four Dragons, but a maximum of two people can share the dragon's power at the same time; there's a limited pool of power, so when a new dragon is born, the old one becomes weaker and dies young. The current White Dragon happened to be the son of the previous White Dragon, but that's not necessarily the rule. The village of the Blue Dragon treats the power as a curse that can strike any of their children even if the previous Dragon did not reproduce, and the previous Green Dragon didn't anticipate the current Green Dragon's birth, implying that he was not the father. [[spoiler:And the Yellow Dragon never passed on his powers, because he's immortal]].

** The Starks, Arryns, Tullys, and Baratheons are all confined to half a dozen or so members at the most, and the inheritances of their various regions are threatened because of it, while the former ruling Targaryen family is down to one (confirmed) member. Meanwhile, the Lannisters, Martells, and Tyrells are all bursting with [[TangledFamilyTree wide and diverse family trees]], with mentions of separate family branches being established. Thicket or stalk, you can still find [[BigScrewedUpFamily screwed-up]] in the Houses, though.

* When it comes to European royalty, the grand champion of averting this trope might well be Edward I of England (the legendary "Edward Longshanks" of ''Film/{{Braveheart}}'' fame), who lived between 1239 and 1307 and fathered ''sixteen children'', nearly all of whom survived into adulthood and had children themselves. According to genealogists who have studied his family line, the man now has close to four million living descendants around the world (most of them are in the United States, Canada, and Brazil of all places...). Apparently all U.S. Presidents except for one are descendants from him - can you guess the exception? [[labelnote:solution]]It's UsefulNotes/MartinVanBuren [[/labelnote]]

* Carrot Ironfounderson is apparently the last living descendant of the Literature/{{Discworld}}'s ancient Kings of Ankh. This has been supported by evidence uncovered by Edward d'Eath in ''Literature/MenAtArms'', and by [[spoiler: Dragon King of Arms']] inability to find a better alternate successor than Nobby Nobbs in ''Literature/FeetOfClay''. By the latter book, it's an OpenSecret, but Carrot goes out of his way to destroy the evidence whenever he can and obliquely explains to Vetinari that he doesn't ''want'' the throne, preferring to be a Watchman because then people would obey him because it's the right thing to do, rather than because he's [[MagneticHero Carrot]], and he'd only take it if there was no alternative. In Carrot's case, the lack of other heirs is at least implied to have been engineered, as he was the SoleSurvivor of an attack on a caravan in which the long-lost royal sword had been carefully hidden.

* In ''VideoGame/TheElderScrollsIVOblivion'', the realm is protected from the land of the Big Bad by Dragonfires, product of an ancient pact. At the time of the game, the last Septim to be Emperor is assassinated, laying the realm open to invasion by the Daedric forces. The main plotline of the game involves finding the hidden son of the last Septim and getting him the Phlebotinum he needs to start the Dragonfires again. Or, at the very least, to stop the invasion... Though it's an aversion as well: the murdered Emperor ''had'' other sons, three of them, in fact, all of whom were taken out in similarly nefarious assassinations shortly before the game begins (making the Cyrodiilian Secret Service the worst bodyguards in history). Martin survived because, as the bastard son of the Emperor, his existence was kept so secret that even ''he'' didn't know who he was. It does not address, however, the fact Uriel's sons were in their 50s and would have their own heirs who could well have some of their own as well. Or Uriel's siblings and nephews. Or any female Septims.

Possibly related to the IdenticalGrandson. Only one in a generation can take the "legacy."

This is curious in itself. Most family trees branch quite a bit due to multiple children having multiple children (and families of important lineage in particular tend to make a point of having [[SpareToTheThrone a "spare" heir]] around to avert any potential SuccessionCrisis). In fact, if you look [[http://en.wikipedia.org/wiki/Identical_ancestors_point far enough into the past]], you reach a point where every human being alive then is either the ancestor of everybody or nobody who is currently alive. Here apparently [[OnlyChildSyndrome only one child was born per generation]]. In older legends, it was explicitly stated that only the firstborn "counts", but the socioeconomic systems that fostered that kind of thinking withered away, leaving only this trope.

* ''LightNovel/UndefeatedBahamutChronicle'' has a justified example in the Arcadia family, whose only survivors are Lux, Airi and Fugil (all children from the same father) because Fugil killed everyone else. The light novels later reveal [[spoiler:that this trope is subverted altogether, as the modern Arcadia family is a branch of the main line. The branch family led a rebellion against and massacred most of the main family. The survivors went into stasis to hide but were found by the branch family who then attempted to finish the job. Fugil (who turns out to not be part of the family at all) stopped them, leaving only three sisters (Listelka, Aeril and Hayes) as the last survivors of the main family.]]

* ''ComicBook/StarWarsLegacy'' seems to hint that this happened. It's been a hundred fifty years, and the only Skywalkers alive are Cade and his immediate relatives. It's hinted that the Organa Solo line got absorbed into the Antilles Fel line, whose descendant is the Emperor. The second volume starred Ania Solo, the previously-unknown last member of the Solo-Djo line (and the only person known to still use the Solo surname), but the book was cancelled before more details about the family could be established.

* ''ComicBook/DisneyDucksComicUniverse'': Scrooge [=McDuck=] is often lauded as the last of the once great Clan [=McDuck=], who's lineage contains knights, merchants, magnates, Templars, and all manner of greatness. This despite the fact that he is only the last MALE member of the Clan, and his two sisters apparently not counting, one of whom had children and grandchildren of her own, these of course being his nephew WesternAnimation/DonaldDuck and his nephews.
* ''ComicBook/TheMetabarons'': Very much the case with the Castakas. A couple of Metabarons actually end up having more than one child, but no collateral family lines are ever formed. Othon's first son, Bari, is accidentally killed by him when still a teenager, and Steelhead's son (Aghora's twin) dies at birth.

** It's never actually said that Michael is the only descendant, the lycan's are specifically looking for a descendant who is a "pure enough source of the bloodline", ie. he's just more closely related to a specific common ancestor than the other people they've tested so far. He's not even necessarily special in any way, there could be plenty of others as close or even more closely related, he just happened to be the first one they found who was suitable for the experiment.

* Averted in ''Literature/ABrothersPrice'', or played straight, depending on how you look at it: all sisters in a family usually marry one husband. All their children are considered children to all of the mothers. Which means that all the princesses have an equal claim to the throne--and will rule together. However, it ''is'' possible to split the family, with the younger sisters marrying a different husband. This was once done by the royal family, and resulted in a civil war over the question whose group of sisters' offspring were to inherit the throne. The protagonist, Jerin, is descended from a prince who might have been killed in said civil war, and has no claim to the throne--but it does look nice on his birth certificate, and [[spoiler: makes him an elegible candidate for marrying the princesses... as well as a potential kidnapping victim, as marrying him could give a woman some claim to the throne if all other potential heirs were dead. Very unlikely with ten living heirs, but the villains intend to find a way...]]

* ''{{Literature/Herland}}'': Herland's women are all descended from one women who (after their men died out) then had inexplicably given birth to a child by parthenogenesis. This mutation passed down from her daughters.

** The Starks, Arryns, Tullys and Baratheons are all confined to half a dozen or so members at the most, and the inheritances of their various regions are threatened because of it, while the former ruling Targaryen family is down to one (confirmed) member. Meanwhile, the Lannisters, Martells and Tyrells are all bursting with [[TangledFamilyTree wide and diverse family trees]], with mentions of separate family branches being established. Thicket or stalk, you can still find [[BigScrewedUpFamily screwed-up]] in the Houses, though.
** In the Starks' case it may be partially justified as all of Lord Eddard Stark's siblings were killed or took the Black before having children, though there are a distantly related branch, the Karstarks. Even without sudden narrowing, Northern Houses as a whole do tend to be streamlined when compared to Southern ones... for good reason. The harsher the environment (the Eyrie certainly counts, too), the greater the chance you'll not find many cousins and cousins of cousins by blood. As, [[HostileWeather Winter]] is harsh: the superfluous, weak or useless get regularly trimmed so the core may live through it. [[ReassignedToAntarctica One]] [[BetterToDieThanBeKilled way]] [[YouHaveOutlivedYourUsefulness or]] [[MercyKill another]].

** The Targaryens tried keeping it [[IncestIsRelative in the family]] too much, and there do seem to be female line descendants, such as the Martells, Plumms and Penroses, and apparently the Longwaters are illegitimate descendants.

** A rare female example. The Charmed Ones are three sisters who are the descendants of 17th century witch Melinda Warren. Apparently, up until the birth of the protagonists, there never were three daughters per generation.
** Kind of subverted in season 4 when we find out about [[LongLostRelative Paige]]. But of course nobody had thought of her yet in season 1 when the trope was established. Unless you accept that there is no limit to the number of siblings as long as there is at least three sisters. Otherwise providence would have to wait until the mother reached menopause to grant the powers to the sisters, because more siblings might still be born. Besides we find out in "That '70s Episode" in season 2 that the sisters had their powers from birth -- presumably because they were always going to be witches, it's just the ''Charmed'' gimmick that wasn't (and couldn't be) established until Phoebe's birth.

** Played straight by many houses whose patriarchs seem to lack siblings. The Stark children have no cousins except Robin Arryn, since Ned's siblings all died or took the black before having children, though they are very distantly related to the Karstarks.

** As of the end of Season 6, this also happens to the Tyrells and Martells. [[spoiler: Since several of their family members had been AdaptedOut while the rest received DeathByAdaptation, both houses are legally extinct which leaves Olenna Tyrell (nee Redwyne) and the Sand Snakes (Oberyn's eight bastard daughters) to rule the Reach and Dorne respectively. By the next season they're all dead as well, leaving both regions leaderless. However in the final season, Varys mentions a ''Prince'' of Dorne who offers support for Daenerys' siege of King's Landing, though it was never cleared if he is a surviving member of House Martell]].

* Subverted trope in Literature/TheBible, of which it's commonly held that UsefulNotes/{{Jesus}} needs both a father ''and'' mother to both be descendants of the entire Davidic dynasty. Through his mother he gets biological descent, and through his adoptive father who has direct male descent he becomes legal heir (although Mary's descent is not explicitly stated). Not to mention that Jesus has several brothers (and there's a possibility that his cousins on his mother's side may also have the same descent).

* Averted in ''TabletopGame/LegendOfTheFiveRings'' where the direct descendants of the two dozen or so gods and heroes that founded Rokugan number in the tens of thousands. And that's not counting the two million or so samurai that carry those gods' and heroes' names through fealty. It does appear in the first Imperial line, but only because when a new Emperor takes the throne, all of the other candidates must renounce their family name and be adopted into one of the secondary Imperial families. Interestly, this does lead to the logical conclusion of the Imperial family being wiped out in the first story arc. An heir turns up MosesInTheBulrushes-style in the third arc... but he's the new BigBad.

* DownplayedTrope in ''TabletopGame/SentinelsOfTheMultiverse''. [[TheCape Legacy]] is a LegacyCharacter who has always passed his powers to his first born, who even picked up an extra power. While any Legacy can have several children, and some did, only the first child will be a Legacy. America's Newest Legacy is the first female Legacy. In one timeline, this trope and her death turned Legacy into FallenHero Iron Legacy, as since there would no longer be a Legacy after his death, Legacy snapped and decided to eliminate evil before his death by any means necessary, [[TheUnfettered no longer caring for collateral damage]] and becoming a HeroKiller, having killed [[PowerArmor Bunker]], [[RobotMaster Unity]], [[BadassNormal Mr Fixer]]...

* In ''VideoGame/TheElderScrollsIVOblivion'', the realm is protected from the land of the Big Bad by Dragonfires, product of an ancient pact. At the time of the game, the last Septim to be Emperor is assassinated, laying the realm open to invasion by the Daedric forces. The main plotline of the game involves finding the hidden son of the last Septim and getting him the Phlebotinum he needs to start the Dragonfires again. Or, at the very least, to stop the invasion... Though it's an aversion as well: the murdered Emperor ''had'' other sons, three of them, in fact, all of whom were taken out in similarly nefarious assassinations shortly before the game begins (making the Cyrodiilian Secret Service the worst bodyguards in history). Martin survived because, as the bastard son of the Emperor, his existence was kept so secret that even ''he'' didn't know who he was. It does not address, however, the fact Uriels sons where in their 50s and would have their own heirs who could well have some of their own as well. Or Uriel's siblings and nephews. Or any female Septims.

* In ''[[VideoGame/RiseOfTheKasai Mark of Kri]]'', the marks are passed down through the first born descendants of six separate families, one mark per family, with at least two of the families having willingly died out to prevent their marks from being passed down any further. In an interesting turn of events, however, it is TheHero's ''younger'' sister who bears the mark, even though he is the first born, though the second game hints that they may not actually be related.

* This is averted with pretty much anyone who had descendants, if you go surprisingly not far back in history. A paper in ''Nature'' demonstrated that if a person has four or five grandchildren, either their line tends to die out within a few generations, or the number of descendants begins to increase exponentially. Someone living two or three thousand years ago will either have no descendants at all alive today, or be an ancestor to a lot of people.

* When it comes to European royalty, the grand champion of averting this trope might well be Edward I of England (the legendary "Edward Longshanks" of ''Film/{{Braveheart}}'' fame), who lived between 1239 and 1307 and fathered ''sixteen children'', nearly all of whom survived into adulthood and had children themselves. According to genealogists who have studied his family line, the man now has close to four million living descendants around the world (most of them are in the United States, Canada, and Brazil of all places...). Apparently all U.S. Presidents except for one are descendant from him - can you guess the exception? [[labelnote:solution]]It's UsefulNotes/MartinVanBuren [[/labelnote]]
* Sometimes intentionally attempted by dynasties to limit the number of people [[SuccessionCrisis vying for the throne, land or fortune]]. Different cultures handled this in different ways:

** One reason why royal entourages in AncientEgypt were so enormous was that a ruling Pharaoh needed to keep all of his ''female'' relations on a tight leash, because the divine grace of rulership was passed down through the female line. Thus, every Pharaoh's court was awash with his own and his Great Wife's sisters, aunts, female cousins, daughters of his predecessors' junior wives, etc, ''none'' of whom could be allowed to marry without rock-solid guarantees of their would-be spouse's loyalty.

** In Japan, the 1947 revision of the Imperial House Law made all the collateral lines of the Imperial family into commoners -- if you're not a direct-line descendant of Emperor Hirohito or one of his brothers, you aren't a possible candidate for the Chrysanthemum Throne. Female children in the Imperial family are also required to become commoners once they marry, so none of their children are candidates. Oh, and that revision ''also'' banned adoption of an heir into the Imperial family (one way the main Imperial family used to tap the manpower pool of the collateral lines). Which means as of 2021, the Japanese dynasty is now resting on the shoulders of a 14-year old boy, as the only possible heir young enough to produce more heirs.