When ThickerThanWater is pushed to its furthest extent, it leads to loyalty to one's entire species.

This generally requires at least one other intelligent species around, to prove a contrast from a general benevolence toward intelligent beings. They are compatible, just as people can support their families more strongly while behaving well toward non-related individuals -- but MoralMyopia is also possible, which can cause FantasticRacist or TranshumanTreachery. A GenghisGambit may be used to cause unity.

And it does not keep members of that race from acting as a DysfunctionalFamily outside of crisis. A united front may be seen only in times of crisis, facing down aliens or a natural disaster. LesCollaborateurs with aliens are often particularly hated for this reason.

May be a reason for MandatoryMotherhood. If a species is in danger, anyone who can have children and doesn't will be accused of lacking this.

HalfHumanHybrid -- or half-whatever hybrid -- may be regarded as treacherous on the parents' part and untrustworthy on the child's, because of it. Technically, all such hybrids should be sterile, since that's the definition of species but many works ignore that.

SuperTrope of ApeShallNeverKillApe.
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!!Examples
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[[folder: Comic Books ]]

* In ''ComicBook/{{Watchmen}}'', the plot was to feign an alien attack to draw this out of humanity.

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[[folder: Film ]]

* In ''Film/ChildrenOfMen'' no children have been born for more than 20 years. Whenever Kee's baby cries it sparks an instant and almost universal reaction of "must protect" or cessation of all hostilities among ''total strangers''. Only one corrupt army officer tries to capture them for personal gain.

[[/folder]]

[[folder: Literature ]]

* In JackCampbell's ''TheLostFleet'' novel "Invicible", the spider-wolf aliens know that the Syndics and the Alliance were at war, and regard the fleet's charge to Midway as their "helping our brother-enemies against our not-brother-enemies", and as extremely impressive.
* In Creator/CSLewis's ''TheLastBattle'', the dwarves' rallying cry is "Dwarves for the dwarves!" They don't want the Aslan side ''or'' the Tash side to win. During the battle they use their arrows to help whichever side is losing at that particular moment.
* From ''Literature/StarshipTroopers'': ''"Either we spread and [[GuiltFreeExterminationWar wipe out]] the Bugs, or they spread and wipe us out - because both races are tough and smart and want the same real estate."''
* Averted in Max Fraj's ''Literature/{{Labyrinths of Echo}}''. Understandable since most humanoid species there are cross-fertile.
* In Sergey Luk'yanenko's "Key Dach" novels, as those take place in a modified ''Master of Orion'' universe.
* In V. Panov's ''SecretCity'', partially enforced by TheMasquerade of the setting when dealing with respective Muggles, with notable differences among the magical nations and among the magical species making those up.
* In V. Zykov's ''Way Home'': both examples (reptarkhs, reprokhorses, light elves, dark elves, high and common dragons) and counterexamples (humans, dwarves, goblins).
* In most works of V. Ivashchenko: united elves, fractioned humans and tribal orcs.
* In AndreNorton's ''Secret of the Lost Race'', an alien race can interbreed with humanity -- and in fact must to reproduce -- and this is greeted with revulsion and accusations of disloyalty by many humans.
* In PoulAnderson's "A World Called Maanerek", Sonna thinks it a glorious thing to make all men brothers again. It is when she learns of the {{Dystopia}}n nature of the Hegemony that she rejects it.
** In ''After Apoclypse'', the human ships seek each other out, both for more humans and in hopes of perpetuating the race.
* In Creator/RobertAHeinlein's ''Literature/HaveSpacesuitWillTravel'', Kip and Peewee ask to return to Earth even if the judgment goes against it, though arrangements have been made to let them live out their natural lives.
* In Creator/SarahAHoyt's ''Literature/DarkshipThieves'', Thena's father complains about her lack of loyalty to her genetically engineered species. [[spoiler:Given that species has been living by cloning its own members and then murdering them to transplant brains into them, she doesn't take it very seriously.]]
* In JohnScalzi's ''OldMansWar'' novels, human conflicts are damped down in the name of unity in the face of the many aliens who want the same planets and resources as us, and are often [[PunyEarthlings far more dangerous than human forces]]. Later books reveal [[spoiler:the human government is using species loyalty to maintain their power over humanity, and that the aliens are not all so hostile - in fact, we're one of the handful of rogue states that would rather stir up trouble than get in line for peaceful disbursement of habitable planets.]]
* In Creator/PoulAnderson's ''Sargasso of Lost Starships'', Jansky appeals to Donovan on this ground -- yes, they are from different planets, but they are all human. Unbeknownst to her -- he knows they are going against aliens, and it invokes this.

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[[folder: Tabletop Games ]]

* In ''TabletopGame/{{Warhammer 40000}}'', the official principle of the Imperium is xenophobic species loyalty. However, the human race has been split by the Horus Heresy, and there are those who willingly use xeno tech. Tau gue'vesa units (indoctrinated and/or voluntary human auxiliaries with Tau weapons) get the Hatred special rule from ''every'' Imperial unit.
** The [[OurElvesAreBetter Eldar]], as well. The Dark Eldar consider the Craftworld Eldar to be weak, unworthy fools, and the Craftworlders consider the Dark Eldar to be absolute monsters (which is a pretty good assessment of them truthfully). However, this does not stop them from banding together to fight a mutual foe such as the Orks or the Imperium. Case in point: in the Allies rules, Dark Eldar and Craftworld Eldar count as "Battle Brothers", while the various human factions count as "Allies of Convenience".
* In {{Traveller}} the wolf-like Vargr fight each other like cats and [[IncrediblyLamePun dogs]]. However they always support each other when their species is even insulted. K'kree actually have species Xenophobia and not just loyalty, which is justified by the fact that most major races are predatory. Humans and Aslan by contrast have a mild species loyalty by comparison. Aslan are loyal to their clan and their code of honor and if their clan happens to be allied to a human empire that is OK by them. Humans in Traveller are as varied as in RealLife and a number of humans are allied with aliens against other humans.
* 1st Edition ''TabletopGame/DungeonsAndDragons''.
** The Player's Handbook had a Racial Preferences Table for humans and demihumans. Each race preferred dealing with other members of its race more than it did other races.
** The ''Dungeon Master's Guide'' had a Humanoid Racial Preferences Table for humanoid monsters (orcs, gnolls, goblins and so on). Each humanoid race also preferred dealing with other members of its race over other races, with a couple of exceptions. Hobgoblins and orcs only preferred to deal with others of the same or friendly families/tribes: they ''hated'' all members of rival families/tribes. Trolls only felt neutral toward toward other trolls and didn't prefer to deal with any other race.

[[/folder]]

[[folder: Video Games ]]

* Pervades the ''Videogame/ChronoTrigger'' / ''Videogame/ChronoCross'' universe, with humans, mystics, demihumans, dwarves, and fairies each only looking out for their own.
* Quite widespread in ''Franchise/MassEffect'', and indeed the primary motivation of the human extremist group Cerberus.

[[/folder]]

[[folder: Webcomics ]]

* ''Webcomic/{{Inhuman}}'' - Myches have this as a borderline hat, after the whole species spending a long time in slavery.
* In ''{{Sinfest}}'', [[http://www.sinfest.net/archive_page.php?comicID=1699 Slick tries to appeal to their all being humans.]] He has to revise it slightly.
* In ''Webcomic/{{Freefall}}'', [[http://freefall.purrsia.com/ff200/fv00200.htm Florence regards herself as a representative of her species, requiring her to act accordingly.]] [[http://freefall.purrsia.com/ff2200/fc02161.htm She wrestles with the possibility of her actions causing her race to go extinct]], but [[http://freefall.purrsia.com/ff2200/fc02162.htm concludes she has to avert]] AMillionIsAStatistic.
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