Along with MonsterOfTheAesop there's a tendency for all the monsters in a given show to be male or female, rarely will there be a mixed bag. The exception is if the TheDragon or the BigBad are a different gender and deign to fight the heroes. And much like MonsterMisogyny applied in reverse, guy heroes will only fight guy monsters, and girl heroines will only fight girl monsters. Though girl heroes fighting male monsters is not uncommon either, [[MenAreTheExpendableGender male is kinda of the default gender for]] {{Mooks}} ([[TheSmurfettePrinciple if not the default gender in fiction]]).

This also tends to follow the predominant gender among the cast. Mostly girl heroines? Then it's female monsters. Mostly guy heroes? Then it's male monsters.

'''There's really two reasons this happens:'''
# It's a lot easier on the costume/animation department if everything is fairly uniform across the board for the generic cannon fodder and slightly less generic MonsterOfTheWeek. There's also an easy story justification when monsters are involved: simply put, they are all modified forms of one design, pressed from a single mold, created by the same spell or, in the case of the first generation of [[Franchise/StarWars Imperial Storm Troopers]], [[CloningBlues cloned]] from the same guy.
# In the case of where the single gender protagonist(s) fight single gender monsters, this is probably to avoid UnfortunateImplications. Violence of men against men and women against women isn't viewed with the same sort of sensitivity as men against women. By reserving the men against women for developed characters (where you can develop very good reasons why they need to fight each other) and not having it for the AlwaysChaoticEvil {{Mook}}s that get steamrolled every episode, you can avoid accusations of the piece being inherently misogynistic or misandristic.

Subtrope of OneGenderRace. See DesignatedGirlFight. Contrast FemaleMonsterSurprise.
!![[blue:Example Boysters:]]


[[folder: Anime and Manga ]]
* ''Anime/CuteHighEarthDefenseClubLove'': the show employs ChromosomeCasting (being set primarily at a [[OneGenderSchool boys' school]]) and the monsters are all [[HeelMonsterTurn people transformed by the villains]].
* In ''Manga/{{Guyver}}'', no female zoanoids are ever featured (though a couple appeared in the American live-action movies).
** Late in the manga a sole female Hyper-Zoanoid does show up, Griselda, one of [[spoiler:Akito's]] Thunderbolts and engineered to block the telepathic influence of any nearby Zoalords. Still quite dangerous in close-combat even if that isn't her primary function.
* ''Mazinger'': Nearly all {{Robeast}}s from ''Anime/MazingerZ'', ''Anime/GreatMazinger'' and ''Anime/UFORoboGrendizer'' were male. Even Rhine X1 (Donau Alpha1 in the original manga), a Mechanical Monster controled by a girl, was male. Maybe the only exception is Marquisse Janus, one of the CoDragons of ''Great Mazinger'': her HumongousMecha was clearly female-shaped.
* ''Anime/ScienceNinjaTeamGatchaman'': All featured {{Mook}}s of Galaktor were male.

[[folder: Comic Books]]
* While most male superheroes have at least one or two well-known female villains, the vast majority of Franchise/SpiderMan's rogues are men. His few recurring villainesses--such as Calypso--have not entered pop culture quite like the Green Goblin and Venom.

[[folder: Fan Works]]
* The Negaverse drones from ''Sailor Moon: Legends of Lightstorm'' appear to be genderless. Despite being at least partially organic, they are described as being built, and so have no need to reproduce naturally.

[[folder: Film]]
* The ''Film/LordOfTheRings'' movies had only male orcs in line with its source material, though in the final movie there are two orcs that appear to be strikingly female, like the one who orders for the catapults during the Minas Tirith battle, and some orcs, such as the one who inspects a freshly born Uruk-Hai in ''Fellowship'', were played by women. Whether they were meant to ''be'' orc women, who knows...
* ''Franchise/StarWars: Film/AttackOfTheClones'' and onward had the Clone Troopers, clones of [[BountyHunter Jango Fett.]]
* All the Mogwai and Gremlins seen in the ''Film/{{Gremlins}}'' movies are (ambiguously) male save one female in the [[Film/Gremlins2TheNewBatch second movie]], who was only such because it had gotten a hold of a gender-changing potion in a lab. Any reproductive processes not involving a splash of water are not discussed.

[[folder: Literature]]
* All Orcs mentioned by name in ''Literature/LordOfTheRings'' novels are male. However, since Tolkien had written that "Orcs multiply after the fashion of the Children of Ilúvatar", i.e. elves and men, there must have been female Orcs somewhere, but given the times and his source materials Tolkein probably just discounted them. There aren't a lot of females on the heroic side either, and all but one (two, depending upon how you count Galadriel) are little more than window dressing.
* In just about any fantasy setting, it is rare for female goblins, orcs, trolls, ogres, or giants to be mentioned. There are of course exceptions (such as Literature/{{Xanth}}, Franchise/{{Shrek}}, and tabletop games run by particularly forward-minded {{Game Master}}s), but they tend to be rare.
** When OurDwarvesAreAllTheSame, Our Dwarves are usually all male as well, or at least, dwarf women aren't recognizable as women to non-Dwarves.
* The [[OurOrcsAreDifferent Koloss]] from ''Franchise/{{Mistborn}}'' are all male, and the one Koloss questioned about it has a hard time grasping the concept of gender at all (and he was a ''smart'' one). [[spoiler: This is because Koloss are an artificial race created by transforming humans with BlackMagic- they don't technically have sexes, because they don't reproduce sexually, but are generally referred to as male]].

[[folder: Live Action TV]]
* ''Franchise/PowerRangers'' tends to limit itself to two female monsters per season, though there ''is'' always at least one female [[TheDragon Dragon]].
** Though a lot of monsters tend to be gender ambiguous at best.
* On ''Series/DoctorWho'':
** Sontaran soldiers are cloned in batches and are always male. The Sontaran Strax in the new series can't quite mentally come to grips with the idea of more than one gender and often addresses women as ''"boy"'' or men as ''"girl"''. He does try his best though.
** Daleks are entirely genderless--and gendered beings of other species who are converted into Daleks become genderless in the process--but they all have the same (shrill) male voice.
** Similarly, Cybermen lose all gender identity when they are converted, but voices and body shape are clearly masculine. One "partially converted" cyberwoman appearing in an early ''Series/{{Torchwood}}'' episode was obviously still female.
** Classic-series Silurians showed no perceivable females, although the new series have quite a few of them.

[[folder: Tabletop RPG]]
* ''TabletopGame/DungeonsAndDragons'' has a few female orcs in the fiction (there is one particular in the latest few Drizzt books). There are rules for them, in that orcs and many other humanoid monsters have tribal rules in their monster entries, covering how many females/elders/infants/so forth should be part of any group of Monster X. Somewhere between the inattention to detail of most games, the vague distaste for genocide, and the fact they don't provide much in the way of XP, they tend to get ignored.
** For orcs, it's justified that you don't often fight females--the males usually treat them as [[StayInTheKitchen breeding stock whose place is in the home]], so in any scenario where conflict with female orcs is possible there's also probably orc kids and babies around, and any sane DM would probably advise players of non-evil characters to tread very lightly...
*** The Forgotten Realms novel Evermeet quotes an Orc proverb "If Gruumsh had intended females to lead, he would have given them bigger muscles."
** And for trolls it's averted, since they're matriarchal.
** This is typically applies to [[TheHyena gnolls too]], which is a little strange since real life hyenas are matriarchal.
* The Orks of ''TabletopGame/{{Warhammer 40000}}'' are basically "drunk football lout" crossed over with "genocidal zealot", and are universally ridiculously masculine. Justified because they reproduce asexually (biologically, they're a lot like fungi).
** This has lead to a lot of interesting little bits of in-universe lore, though. Such as if a planet's ever invaded by Orks, even an Exterminatus might not be enough to get rid of them, and their spores, completely, and their version of a doctor being able to work in a perfectly effective manner, despite being a psychotic chainsaw nut that harvests spare parts and stick them onto those in need at near random.
*** The spores just don't make more orks; they also make the fungi and squigs they eat, and the lesser greenskins to farm and help the orks. In other words ''a single ork can make an entire ecosystem.'' (This is the main reason why orks are so good at fighting the Tyranids.)

[[folder: Video Games]]
* The ''VideoGame/DonkeyKongCountry'' series had no female Kremlings until Kalypso and Kass appeared in ''VideoGame/DonkeyKongBarrelBlast''.
* The Super Mutants of ''VideoGame/{{Fallout}}'' all look male, but it's revealed in files that the FEV virus which creates them makes both genders visually identical (secondary sexual characteristics like breasts and high-pitched voices disappear). Indeed, in ''VideoGame/FalloutNewVegas,'' there are several female Super Mutants who, yes, sound exactly like the men (though they don't necessarily act like the men; one is a sweet old granny).
* ''Franchise/{{Halo}}'': Virtually all the Covenant soldiers we see in the games are male (the ones that ''have'' a gender, anyways), though we see a lot more females in the expanded universe. This is justified by the Elites and Brutes, who have patriarchal warrior societies. This is also justified by the Jackals in a different way; they live in a matriarchal society where the females do the commanding and the males do the fighting. ''VideoGame/{{Halo 5}} finally introduces a Sangheli female as a member of the Arbiter's "heretical" resistance cell, but only as a voice over a radio.
* In ''VideoGame/TheElderScrollsVSkyrim'', there appear to be no female giants.
* SamusIsAGirl, yet all space pirates in ''Franchise/{{Metroid}}'' are referred to as male. In fact, almost everything Samus fights is either male or gender-neutral. Of the few female characters other than Samus, [[EvilTwin Dark Samus and the SA-X]] are only "female" by the technicality of being Samus's EvilTwin, and the Mother Brain is a giant brain in a jar and displays no obvious female characteristics. The only enemies Samus ever fought who were definitely female were the Metroid Queen and Gandrayda.
* The orc part is averted in the ''VideoGame/{{Warcraft}}'' series, a female orc was seen as early as ''VideoGame/WarcraftOrcsAndHumans''. Though being an army building game, its mostly played straight with the other races, female humans alone weren't seen until the third game and it took till ''VideoGame/WorldOfWarcraft'' for females of most of the other races such as Trolls, Tauren, and Dwarves to show up on screen.
** Pretty much played straight with most other monstrous races. Ever seen a female ogre, sea giant or fel orc?
* The later ''VideoGame/{{Wizardry}}'' games. In ''Bane of the Cosmic Forge'', all dwarves, giants, gremlins, knights, samurai, ninjas, and rogues are male. In ''Crusaders of the Dark Savant'', all Rattkin, Gorn, Munk, Dane, and Umpani are male. There is only one T'Rang female, justified in that she's a bloated egg-laying queen, and ''Wizardry 8'' adds the Rattkin females... most players rather wish they hadn't.
* ''Franchise/{{Pokemon}}'' has quite a few single-gender mons, starting with the Nidorans in ''Red and Blue''.
* In ''VideoGame/FinalFantasyTactics'', the thieves have an ability "Steal Heart" that charms the opponent, but only those of the opposite gender of the user. All monsters are considered male with regards to this ability, which means [[GameFavoredGender female thieves have an advantage]]. [[BellisariosMaxim Don't think about this too hard.]]

[[folder: Web Comics ]]
* Rich Burlew explained in a Q&A about ''Webcomic/TheOrderOfTheStick'' that he deliberately made the Hobgoblin army all identical males in contrast with the variety of human soldiers (of both genders) as a quick way of characterizing the Hobgoblins as evil {{Mook}}s.

!![[pink:Example Girlsters]]

[[folder: Anime and Manga]]
* ''Manga/CardcaptorSakura'' mostly fights cards that seem female when they aren't too ambiguous, but this might be just because they're so cute looking.
** With some of the things implied about their in-universe creator, it'd be unsurprising if he specifically decided he wanted them cute looking.
* ''Anime/CuteyHoney'' may possibly be the UrExample, being the forerunner to the MagicalGirlWarrior subgenre of MagicalGirl series. True to the [[Creator/GoNagai author's]] style, the monsters, while female, were always ''[[{{Gonk}} hideous]]''.
** However, the Panther Claw mooks that Cutie Honey could mow down several of in each episode are all male.
* While ''Anime/SailorMoon'' arguably popularized the female MonsterOfTheWeek and MonsterOfTheAesop tropes, and unlike ''Cutie Honey'' usually gave those girl monsters super model proportions and porn star attire, the show actually averted this trope throughout its run: monsters were generally a mixed bag of genders, even when having mixed genders wouldn't make sense, like the fake-sailor-senshi Phages from the ''Stars'' season. Sometimes, it depended on who summoned them: Fisheye from the Amazon Trio in the fourth season only targeted males and thus only summoned male remless/lemures to fight the Sailor Scouts. The only reason people ''think'' the show followed this rule is because female monsters were more common during the more popular seasons.
* In what is probably a nod to ''Anime/SailorMoon'', the ''Anime/PrettySammy'' series employs exclusively female "Love-love Monsters", which are mundane objects animated into anthropomorphic creatures with similar traits.
* Based on their voices and booklet art, all of [[NightOfTheLivingMooks the Marriages]] of ''Anime/MagicalGirlLyricalNanoha [=StrikerS=] [[AllThereInTheManual Sound Stage X]]'' appear to be female.
* All of the [[HumongousMecha Dolems]] in ''Anime/RahXephon'' had female characteristics, their avatars were women in [[{{Stripperific}} skimpy outfits]], and their Mulian controllers were all women as well. There are two exceptions, both of whom are plot relevant to the lead and the tormented leader of Terra.
* Zig-zagged in ''Manga/{{Claymore}}''. The [[AmazonBrigade all-female]] Claymore warriors mostly fight male Youma, but the most powerful Youma are the Awakened Beings, who are female due to [[WasOnceAMan being former Claymores themselves]]. One of the first big {{Plot Twist}}s of the story comes when the characters encounter a ''male'' Awakened Being. [[spoiler:In fact ''most'' Awakened Beings of note seem to be male - unknown to the protagonists at the time, the reason Claymores are always women is because the Organization's initial male Claymores were much more vulnerable to Awakening, and large numbers of them managed to escape before they could be put down. Due to improvements in Claymore technology over time, however, younger Awakened Beings tend to be stronger than older ones of equal rank, and the absolute strongest enemies in the series are female.]]
* In ''Anime/PuellaMagiMadokaMagica,'' all witches are all female... [[EldritchAbomination not that you could tell by looking at them]]. [[spoiler:They're actually [[TheCorruption corrupted]] [[MagicalGirl magical girls]]]].

[[folder: Literature ]]
* In the Literature/{{Xanth}} series harpies are all female. As a notable exception to the norm in this series this naturally becomes a plot point in one of the books.
* This is what everyone thought about the Dragon Princesses from ''Literature/InCryptid''. Turns out that they're [[spoiler: female dragons with an extreme case of sexual dimorphism and the ability to produce daughters through parthenogenesis. They need to mate with male dragons to produce more males and periodically introduce some genetic variation into the females.]]

* The Weeping Angels in ''Series/DoctorWho'' all appear as feminine statues, though given their power it's unclear whether it's merely their "stone" appearance.

[[folder: Video Games ]]
* The Helazoid race in ''VideoGame/{{Wizardry}} VII: Crusaders of the Dark Savant'' are a thriving all-female culture. Justified by their use of advanced technology to reproduce and only produce female children.
* In ''VideoGame/ScarabOfRa'', the pyramid is infested with monkeys, cobras, and ''lionesses.''
* In ''VideoGame/WarCraft'' all Harpies are females.
* Besides Pyramid Head and the Abstract Daddy ([[spoiler:which is a monster created by Angela's mind]]), all the monsters in ''VideoGame/SilentHill2'' are vaguely feminine in appearance. As an inverse of the usual usage of this trope, it makes the male player character fighting them more disturbing.
* In ''VideoGame/FinalFantasyXIV'', almost all of the beastmen are a mixture of male and females, but they all have builds that look more suited to males. The Anata are a race of snake people that are exclusively all female and they find the concept of other races needing males to reproduce a little odd.

[[folder: Web Comics ]]
* The three peanut butter monsters in ''Webcomic/TheInexplicableAdventuresOfBob'' are all female, since they're all [[CloningBlues genetically identical.]]

[[folder: Western Animation]]
* In ''WesternAnimation/StevenUniverse,'' it's eventually revealed that all the monsters are [[WasOnceAMan Gems who have been]] [[TheCorruption corrupted]] by a FantasticNuke; thus they are thus all female, [[OneGenderRace like the Gems themselves]]. You wouldn't guess this from looking, as their corrupted forms are too inhuman to resemble any gender, often not even looking like animals.