Look closely at a female reptile, a female amphibian, a female bird, a female fish, a female insect, or most non-primate mammals. You'll doubtless notice the lack of a particular characteristic that is common to female humans. Most animals do not have human-like breasts at all, even if they fall into the category "mammal". Compare the bellies of a male and female dog, or even the chest of a female gorilla, and you won't find much difference unless she's recently given birth to a litter and is nursing young (that's about the only time she will ever have any vague semblance of what we call "breasts" on humans). Both the size and position of human breasts are likely the results of bipedalism— or more likely, the longer infancy-period of humans in relation to other animals (see "female gorilla" above).
Regardless of this, artists tend to oversize the mammaries of characters that do have them, or put them in places where they don't belong. Prominent breasts, or lack thereof, is one of the simplest instinctive visual cuesfor hominids. Giving all female animals big boobs, or at least a body shape that mimics them, allows for distinction between the sexes without adding glaringly obvious costume tags, a wasp waist, or the more bizarre gender-specific characteristics in some other animals. At least, that's a common reason given. Undoubtedly Fanservice plays a big role, as does Men Are Generic, Women Are Special; after all, male characters never have prominent crotch bulges to distinguish them from female characters.
If the character is an alien or artificial life form, then it makes a little bit more sense. Aliens have Bizarre Alien Biology after all, and creators of synthoids and such would probably want their "children" to be anthropomorphic enough to fit in. Not to mention that it's easier to design a skin-tight rubber bodysuit with strange textures for use by human actors. However, it tends to make a lot less sense when applied to avian and reptilian races of creatures or aliens. Breasts are for nursing young, and for an Avian with a nice hard beak (especially those with curved or hooked beaks) that would be incredibly painful. Reptiles often have sharp teeth and often strong jaws, too, same with some fish. Remember, breasts are primarily for nursing young - not just to look sexy.
This is common in the Furry Fandom, though some furries prefer to just portray a reptile, avian, amphibian, or their mythical cousins (Gryphons and Dragons) without them for anatomical purposes. Even when this trope is averted in canon, it seldom stops the Fan-Artists. There is also the school of thought of multiple breastson aliens or furries but that's a completely different subject altogether.
Just in case male non-mammals feel left out, note that external genitalia and nipples are also a "mammal thing", and their presence in male creatures from other taxonomic groups is a variant of this trope.
This Trope is sometimes found with Non-Mammalian Hair, hair being something else that only mammals have but is often added to non-mammalian females. Compare Bizarre Sexual Dimorphism, Multiboobage, Secondary Sexual Characteristics, Tertiary Sexual Characteristics, and Feather Fingers.
open/close all folders
Anime & Manga
Technically every Digimon with breasts ever, but special mention goes to Arukenimon, a spider woman. They're not immediately noticeable, but they're there. Justified as it's based on a Youkai known as the Jyorogumo (prostitute spider), a spider demon that poses as a beautiful woman, often a hooker, to lure unwary men to its lair to be eaten and/or fed to its young. Presumably its "breasts" are something it evolved as a form of aggressive mimicry.
The original origin story for Marvel's first Spider-Woman, Jessica Drew, was that she was a hyper-evolved spider who had been genetically engineered by the High Evolutionary to look completely human (some people, apparently including Stan Lee, felt that this was going too far even for comic book science), and a well-endowed human at that. This origin story was retconned away to be that she had been bitten by an irradiated spider pretty quickly though, so this issue did not come up for long.
A spider who teaches Katy to knit in Katy Caterpillar has an impressive set of boobs.
Spydra from Gadget Boy & Heather. However, she appears to just be a woman in a spider costume, and being an Expy of Dr. Claw from the original Inspector Gadget cartoon very little is known about her true self.
Mocked by legendary Disney comic book artist Carl Barks himself. One humorous self-portrait◊ showed him making a sketch of a sexy, nude woman... using a rather annoyed-looking duck as a model.
Daisy herself has appeared on occasion in the old cartoons to have breasts in shorts like Mr. Duck Steps Out and Donald's Double Trouble. Obviously, this wasn't permanent, and except for a few instances like Quack Pack, she's been dodging the trope since then. She does, however, have a body shape that *suggests* womanly curves.
In the Marvel Universe, the Shi'Ar are specifically stated to have evolved from birds (this is the reason why Deathbird, a Shi'Ar who is an apparent evolutionary throwback, has both wings and talons on her fingers). They also reproduce by laying eggs, which are incubated in a communal hatching chamber. Yet they are portrayed as humanoid in all other respects, including female Shi'Ar having breasts.
As indicated in The Comics Curmudgeon's quote at the top of this page, the comic strip Shoe gives breasts to every single female in its all-avian cast.
The italian comic Ava features this. To be clear the main characters are a humanoid duck and chicken, and both have not only huge breasts but also a slim waist and other stuff.
Films — Animation
In Happy Feet, the penguins are barely stylized at all, but the females have shading in their chest feathers to suggest a bosom. Truth is stranger than fiction; it turns out that Emperor Penguins do keep a milk-like substance stored in a gland by the esophagus, but it's actually the males that do this.
The Contessa, Hungarian hawk and Olympic fencer in Animalympics, has a shapely figure both above and below, accentuated by a dashing blouse and riding breeches. She also has eyeshadow and eyelashes for good measure. Other bird characters, like Babwa Warblers, are treated more naturally; Contessa happens to be the most human-like.
The female birds in the Disney film Valiant have much more prominent chests than the male birds, particularly the main character's obligatory love interest, a small nursing dove. The females also have a small central indention and shading in the chest that would suggest cleavage.
Films — Live-Action
In the otherwise wretched film version of Howard the Duck, the eponymous avian hero at one point ogles a "Playduck" centerfold, who not only has breasts, but has nipples. And only a few minutes later, we get "Duck-Tits!Woo-oo!" (Riffed starting at 1:53 in the video, NSFW...)
ASAIR one of animations in Super Size Me suggested that McNuggets was made from old hen breast. And by breast I do not mean the meat which is on rib cage but old-human-like breast. It Makes Sense in Context. They were explaining how originally, McNuggets were made from chickens with larger than normal breasts. So to demonstrate, they drew a chicken with pendulous breasts so big that it had to walk with a cane.
The Omwati of the Star Wars Expanded Universe are apparently bird descendants that look like humans with feathers. This includes breasts on the women.
China Miéville's Bas-Lag books feature a lot of xenian characters, some of which fall under this trope. His garuda are a bird-like Winged Humanoid race, female members of which possess slight ornamental breasts useless for lactation.
The album Atomic Roooster by Atomic Rooster features a flying bird with naked human breasts. In a transparent cube.
The fan-spoof Girls of Talislanta series erupted into controversy when the avian Aeriad were drawn with breasts. The controversy was eventually solved when the pose was changed so that the female Aeriad faced the other way.
This is played with in Serious Sam 3 regarding the Scythian Witch-Harpy, which appear to be humanoid women with bird wings and feet. The creature's data file indicates that its breasts are actually non-functional, and are merely a false facade (a form of evolved predatory mimicry) used to attract primate prey for the harpy to kill and eat.
Wave the Swallow, per usual for post pubescent Sonic the Hedgehog cast, of Sonic Riders, though there is as much official art being flat-chested as official art showing budding of the chest. The in-game model tends to the former.
Starbound has the Avian, a group of alien birds who resemble jays. The females are noticably busty.
Suicide for Hire features birds with breasts. This can't be passed off as puffy chest feathers as some similar instances can, as Hunter Ravenwood once declares an avian ex-pornstar to possess "absolutely awesome areolas". The same comic also features reptiles with some fairly impressive hairstyles. Yikes.
Nazi spy pigeon Hatta Mari in the Looney Tunes short "Plane Daffy". Also a red headed duck who called herself 'The Body' that was strongly attracted to Daffy Duck in the cartoon "The Super Snooper".
The Mighty Ducks series has three prominent examples of this, with Mallory, Tanya, and Lucretia. All of them, are female, anthropomorphic, alien ducks.
Regular Show has Margaret the cardinal. In her first appearance, she's showing sideboob, and in her second (which was part of a brief dream), she has on a Seashell Bra.
Several original female duck characters on the cartoon DuckTales. One of the stand outs being Featherika Von Strangeduck in the episode "Hotel Strangeduck". Male ducks like Launchpad have their bills shaped like chins — and having arms and hands rather than wings, and speaking English, etc. — so breasts seem in line with these other adaptations.
The Penguins of Madagascar episode "Miss Understanding" has Skipper thinking he's a female due to a misreading of a DNA test result. During a few scenes showing how his new gender identity causes confusion during missions, the boys go for the chest bump after a successful completion but Skipper and Rico are both uncomfortable with that due to Skipper's newfound (and nonexistent) female features. Notwithstanding that they're BIRDS and don't have mammaries to begin with (or that Skipper really ISN'T a female anyway).
Every adult female bird in Birdz, but Miss Finch ups the ante with Hartman Hips. And Morty is a rare example of "male non-mammal with nipples".
Gorgeous Gal from the Woody Woodpecker cartoon A Fine Feathered Frenzy. She was an overweight and elderly crow with large breasts. Although because she was overweight each breast was almost the size of the Woodpecker himself. Played as a double entendre when she appears on a large black and white TV screen from her chest up wearing a low cut evening gown. When she was right behind the Woodpecker Gorgeous Gal asked him with her sexy voice, "How 'bout a twosome hon?"
The other prominent female character in Beast Wars, Airrazor, while not as obvious as Blackarachnia, still had a rather conspicuous chestplate. The Transmetal version of her that never made it into the cartoon plays it straight.
The pigeon, the rooster, and Duck from Almost Naked Animals have nipples. Also, The female ducks in the episode "Duckling Duck" have boobs.
The Cuban animated short La Pavita Pechugona features a female turkey with an over-sized bust. The link to this short.
The collector's club comics-exclusive Beast Wars character Antagony is a black, female version of Inferno (who technically ought to be female anyway, considering he turns into a soldier ant, but that's neither here nor there). The compound eyes on her chest, made from the head of her ant mode, are usually drawn as boobs.
Honey B. from Banjo-Kazooie sports a pretty impressive pair, and a distinctly waspish waist. In fact, this applies any time a bee- or wasp-like character in a funny animals situation isn't a gigantic engine of stinging death instead.
In both Bug and Bug Too there are examples. In the first title there's Bug's girlfriend, while the sequel sports some multiarmed amazons with large breasts in some levels.
Q-Bee of Darkstalkers fame similarly has a female body with... generous proportions. But it's revealed that this is all a ploy to capture unsuspecting men for her and her hive to mate with and eat (in her victory poses, she even pulls out a knife and fork). This is most evident by the fact that, in her battle stances, she is posed with the buglike eyes on top of her head leading the body, since the ones on her face are entirely decorative (and form part of her mouth).
Dreamwalk Journal is all about a world of nude anthropomorphic insects and arachnids with exaggerated sexual characteristics, including huge boobs on all the females (They apparently use breasts for storing honey or whatever rather than actually nursing). That's all you need to know about it.
This is common in One Piece, in which zoans (people who can turn into animals) usually retain several human features in their half animal form, including hair and, in females, breasts. Even in the case of two female characters who can turn into snakes. At least they didn't have nipples.
The Skrulls of the Marvel Universe are usually referred to as reptiles; they're green, anyway. Would be justified, as they are shapeshifters, if the few female skrulls shown in their "natural" form weren't as vulnerable to the Most Common Superpower as everyone else in MU. They have hair, so maybe they're egg-laying mammals, not reptiles; apparently they lay eggs and then nurse their young after they hatch.
Nessie from Richard C. Moore's Boneyard, despite being a female version of Gillman from the Creature of the Black Lagoon, outsizes all the other girls by several cupsizes. This was lampshaded in an issue that took place at the beach when one of the characters asks "Why does a lizard have such huge tits anyway?"
Tricerachops of Super Dinosaur is a half-dinosaur, half-human mutant who evidently has mammaries.
In the Sigil series from CrossGen, female saurians have pronounced busts.
In the German Club Nintendo comic, one storyline has an apparently older Wendy O. Koopa drawn with hair and breasts.
In the Shadowchasers franchise, the ophidia are a race of Snake People where this is common for females, and Non-Mammalian Hair is occasionally found on both genders. This is actually brought up one chapter of the second fic, where it states a female ophidia's mammaries are non-functional, and if they ever nursed their young, it was millennia ago. (And along with their hair, it also suggests they may be more closely related to humans than some members of both races will care to admit.)
The Falleen from Star Wars, although, technically, they're reptomammals. Granted, there were indeedmammal-like reptiles in prehistoric times. But designating the Falleen as such was probably an attempt to justify this trope. And anyway, if they fed their young on milk, it's very likely real synapsids did it like modern monotremes, who secrete milk from a diffuse region of skin and thus don't have... "large tracts of land". The real reason is because Falleen are supposed to be appealing to a wide variety of species, and being human-created this means breasts must be on the females.
In Larklight, a reptile girl (who is presumably the equivalent of a teenager) is remarked upon as not having these — specifically in the context of how ridiculous it makes her look when she wears a dress not specifically tailored for her. The tail doesn't help matters there.
The Abbai in Babylon 5 are clearly amphibians, but still have breasts. The official tie-in guide explains it away as a structure of coiled tendrils that have a similar purpose but are not actually breasts. It's all a coincidence, apparently...
The Yuan-Ti in are snake people. It may have something to do with being able to inter-breed with humans (indeed, some supplements explain that "the yuan-ti are descended from evil human cultists who mixed their bloodlines with those of serpents", which is itself impossible); but it was probably due to... "artistic license". In some editions, this is explicitly the result of magical assistance from a demon lord worshiped by the cultists, making it a case of A God Did It.
4E has this with the Drakkoths, which are an unusual mixture of crested lizard upper torso and the body of some sort of spiny-tailed drake in the style of a centaur. The females, despite the obvious reptilian nature of these creatures, have breasts.
Many fans of the game that followed the online discussions around the time of the realease of 4th Edition might remember the Internet Backdraft concerning the new Dragonborn race that was Dragonboobs!!! In 3.5 they had an excuse: Dragonborn were created by magical religious ritual from humanoid volunteers, who kept attributes from what they used to be after being transformed (so a dwarf might become a short and stocky Dragonborn, and a female might have two subtle rounded shapes on the upper part of the torso).
Medusas are likewise endowed, but depending on which edition's artwork you go by this is either perfectly logical (only snaky hair) or slightly squicky (scaly and monstrous all over).
The artwork accompanying one of the Voyages of the Princess Ark CD&D articles in Dragon included a female lizardfolk shaman with substantial breasts.
The (presumably male) artists of the German Fantasy tabletop roleplaying game Arcane Codex like to put breasts on everything. Even on the females of reptile people. Considering that Arcane Codex has at least a dozen playable races and more classes to choose from, with full-color artwork in scantily-clad detail, that's quite a lot of breasts. They'd probably put breasts on seahorses, if they could get away with it.
In Exalted the signature Casteless Lunar NPC, Madame Vert, is seen most frequently in her hybrid beast(wo)man form, a humanoid Claw Strider with the proportions of a swimsuit model such as here; WARNING: nipple outline may make this NSFW. While there's some sense there — her most natural shape being a human woman — it's still breasts on a scantily-clad lizard-woman.
Everquest II made Iksar females significantly slimmer than males, and gave them breasts, albeit breasts that could only be described as "minimalist" by MMORPG standards.
Several Kremlings from the Donkey Kong Country series (particularly Klump and K. Rool) have nipples. Klump◊ also provides an example of non-mammilian manboobs.
The Argonians in the world of The Elder Scrolls... although this was temporarily dropped for Morrowind (unless you install certain mods). This accomplished little other than quite bluntly demonstrating the usefulness of this trope, as it was suddenly quite hard to tell male and female Argonians apart in that game. However, closer examination reveals males typical have wider heads, differences in body shape and different coloring. That and females have different hair from most males, and the two genders have different voice actors.
The Tarka in Sword of the Stars appear to be reptilian. Their females lay eggs but have clearly-defined breasts. However, the manual states that their internal structure is much more similar to primates than reptiles.
In the Pardus browser MMO the Keldon species has breasts. Why? as the original maker of the images said, "Keldon women do have boobs. Reason: because I like them and I did the original race design, and Baldur [Game Developer] has agreed upon it."
The Final Boss of Drakensang, Malgorra goes in One-Winged Angel and turns into a giant, three headed serpent. However, she still retains her nipless breasts at the base of her central head.
As part of her Skylanders redesign, the plates on Cynder's underside were modified so that her upper chest has two plates side by side and are noticeably round, while the rest of the plates are flat. Her design got tweaked a bit for Skylanders: Giants, and her new toy is completely flat.
The Pokémon Nidoqueen has prominent breasts for an evolutionary line that appears largely reptilian. Furthermore, Nidoqueen (and its pre-evolution Nidorina, due to a bug that was preserved for continuity reasons) is one of the few Pokemon that can't breed at all, making the breasts doubly useless.
Why do the female Saurians in Star Trek Online have breasts? It's not even as if, being a Federation race, you can put them in an armoured corset and have them show off the goods.
Guild Wars 2 has the Krait whose females have mammaries just like a mammal would, how functional said mammaries are is up for debate. But given that the Krait appear to work in groups and communities, it is possible that they do breastfeed their young.
Wereworld is set on a planet where "Lycanthropes" can shift between animal, human, and hybrid form. All female Lycanthropes have breasts. There are also dragons (who are not Lycanthropes) and the females of the species have no breasts, no hair, no nipples, nor anything that would indicate their gender to a human when compared to the males of the species (they have mohawk-like ridges and horns that look like hair, but no actual hair). This is spotlighted when Blaze, a female dragon, is chosen to make contact with the main character as a messenger of the dragon council. It is quite a humorous scene when Aris, another female dragon, tries to explain to Blaze that she looks like a male to other species, regardless of how sexy she looks to dragon males. This is fixed with the dragon unique ability to shapeshift, which she uses to assume a more human form. However, Blaze misunderstands Aris's explanation of "the importance of having breasts among the other races", and gives herself far too large breasts. This led to Blaze's humorous line "If you're gonna do something, do it grand". So far, no other non-mammal lycanthropes have shown up to compare the dragons to.
Played with in The Order of the Stick, strip #676, where only one of the two reptilian hookers has breasts — they're implants, which her co-workers find ridiculous. (Given the accompanying dialogue, this is likely a reference to the dragonborn, as mentioned above.) Lampshaded in the prequel book Start of Darkness:
Harkovast, a fantasy webcomic featuring various animal races, features a reptilian race called "Tsung Dao" whose females fit in this trope. However it is explained that in this magical setting, all races can cross breed, making the need for mammary glands a somewhat universal adaption.
In an episode of the U.S. Acres segment of Garfield and Friends, Sheldon the unhatched chick is mistaken for a turtle egg by a mother turtle with rather noticeable cleavage. On her shell! How are those supposed to work? (Insert your own "breast plate" joke here.)
Beans, the main female character in Rango, has obvious breasts. There's also a background frog character who has Gag Boobs.
Shinryaku! Ika Musume: Ika Musume is supposed to be a squid, yet she at least seems from this side of the dress to have the chest — and general appearance, tentacles notwithstanding — of a female human in her early teens. She's also an invertebrate, as stated on the DVD cover, but you'd think from looking at her that she has an internal skeleton, so...
The Merrow of the Lorwyn setting of Magic: The Gathering, where the males and females would be indistinguishable if not for the breasts.
In Twilight Princess, both male and female Zoras are identical and flat-chested. The deceased Zora queen, on the other hand....
The Naiads from God of War. Poseidon apparently gussied his daughters up, presumably to make Spartans want to make out with them.
In Call Of Cthulhu: Dark Corners Of The Earth, Hydra, giant queen of the fish-like Deep Ones, is depicted with breasts. It is known that Deep Ones can interbreed with humans, and therefore must presumably share some genetic material, and it's worth noting that the usual reason of making the female creature more attractive/feminine definitely doesn't apply here — imagine the Stone Age fat goddess idols, and add a few extra pairs of breasts, scales and sharp, fishy teeth.
Parodied by the Mermaids in Tales of MU. They have breasts but are ignorant of lactation. Instead, they are used to get free beer and lure sailors to their doom.
On Captain N: The Game Master in the episode I Wish I Was A Wombatman there was a short well endowed blonde haired pink octopus who wore a pink dress. She fell in love with Simon Belmont at first sight even though he wasn't interested. The cartoon ended with her chasing him so she could make love to her 'dream boat' all while leaning forward and exposing the top of her ample cleavage.
Short-lived series Fish Police features anthromorphic fish. Didn't help one of the main characters was a blatant pandering todads who might be watching. This also applied to the comic that the show was loosely based on.
Female Decapodians from Futurama are humanoid shellfish. As Decapodians die immediately after mating, leaving their fertilized eggs behind in the sea, females of their race would never get the chance to use breasts as Nature (as opposed to Fanservice) intended. According to Word of God, their "breasts" are actually egg sacs. Still, the ones with the biggest are considered the most desirable.
A bad case of research failure resulting in unintentional squick is the advert for Nestlé Cereal Bars on UK TV, using an animated character called "Uter the Cow". Uter spoke with an Arnold Schwarzenegger-style voice, and had some sort of gun-like contraption, attached to his(?) udder-area by means of a long tube, out of which he expelled what was presumably meant to be milk.
Films — Animation
In a trailer for Ice Age 3: Dawn of the Dinosaurs, Scrat the saber-toothed squirrel gets all the fur ripped off his chest, exposing two dots of nipple. Not only are there fewer nipples present than seems plausible for his species, which would presumably have large litters like other squirrels, but rodents' nipples are generally arranged in paired lines that extend forward from the groin to the chest, not one pair on the chest as in human males (and females). And male rats and mice don't have any at all.
Space Jam features Lola Bunny. Complete with boobs.
Fritz the Catheavily abused this, featuring bared breasts in nearly every scene in a world populated only by animals.
Played with in the Discworld novel Feet of Clay, where with Cheery noting about how hard it is to be openly female and a dwarf, Angua (a werewolf) muses internally that at least she doesn't feel like she should be wearing three bras sometimes.
In one of the Myth Adventures novels, a woman is attempting to use an illusion to look like a werewolf despite never having seen one. Later on, when she meets one, the female werewolf laughs over the, "And you only had two breasts."
Somewhat related: the Redwall series has a unique problem. Most of the characters are mammals, but there are no non-anthropomorphic mammals (besides the horse in the original novel and it's been more or less retconned out at this point). Yet they are always eating cheese. It was eventually explained that the milk is "Greensap milk", produced from "roots and tubers". (Mm, tastes like Deus Ex Machina. But at least it avoids the potentially embarrassing problems of locating the real stuff...)
On one episode of the Nelvana cartoon, Matthias suffers an instance of Marshmallow Hell at the paws of Constance Badger. (Constance is the only character to have noticeable cleavage.)
Weird example: In the nature Mockumentary book Snouters, one species of this fictious mammal taxon always sports prominent breasts resembling those of humans... even in males. Justified, at least in theory, because the species in question lives symbiotically with another, and trades milk for this other species' assistance in finding food. (Doesn't explain why the breasts look so much like a snippet of Playboy got photoshopped onto a fuzzy little critter, though.)
In Taylor Anderson's Destroyermen series, there exists a species of cat-lemur humanoids called Lemurians, fittingly enough. Lemurian females have been noted early on that proportionality with humans are very similar, specifically the breasts. This leads to some comedic/awkward moments as the bulk of the humans are sex-starved males, and one of the secondary conflicts of the series.
In M.C.A. Hogarth's Paradox series the Pelted races vary considerably on this point, considering they lie all over the Sliding Scale of Anthropomorphism. The alien Chatcaava are said to be mammals (despite looking like dragons) and most of their females have human-like breasts, the Slave Queen being an exception, given her more masculine secondary sex characteristics.
In a MADtv skit, Babe the pig is a half-human, half-pig who is on Baywatch. All of the Baywatch lifeguards are upset until he gets a bikini top which covers his multiple rows of nipples.
This issue comes up a lot where anthropomorphic cattle are concerned. (And see also Furry Confusion.) To wit:
There was a rather amusing discussion on whether female minotaur PCs of the text-based RPG Grendel's Revenge had "Udder Armor" or "Breast Plates" as part of their armor set. Thankfully, One Size Fits All provided no specific answers.
Similarly, female Tauren in World of Warcraft have normal human breasts instead of udders, making for some really weird appearances. Though proportionately, tauren females are quite petite compared to the other races.
Minotaurs in the Dungeons & Dragons setting Dragonlance. In one piece, a human taken captive by seafaring minotaurs notes that the first mate, whom he'd initially mistaken for male, has (modest) human-like breasts beneath her leather armor.
The original Monster Manual portrayed Gynosphinxes this way too.
Rifts plays it both ways. Female Dog Boys are engineered to have humanlike busts apparently solely because it makes them more familiar and acceptable to humans... but considering the variation between canine-like and human-like physiology within the species it's possible some don't. Kill Hounds, which are more in the plausible deniability column, have no such niceties. The feline Battle Cats have humanlike breasts as well. Their Kill Cat cousins, the rat and bat conversions, and the Ursa Warriors are anyone's guess; very little art of them exists.
A female Mutant Rat in the Machinations of Doom comic has 'em.
Wing Commander seems to be a little confused about this. In the "Secret Missions" add-on to the original Wing Commander, the Kilrathi priestess is shown with a multi-part bra covering three sets of human-style breasts, while the Wing Commander Academy cartoon showed the relatively few females that were seen as being flat-chested, and the intro to Wing Commander Prophecy has a wall drawing of a Kilrathi female with one pair of human-style breasts.
The female Khajiit lion-people in The Elder Scrolls, who have normal human breasts. In Oblivion, this almost seems like laziness on the part of the developers, as all humanoid characters have the exact same male or female body model, merely retextured and with a few features added (Claws on Argonians, tails on Khajiit).
The fox spirits in Jade Empire have rather... pronounced... secondary sexual characteristics. They're a rather obvious expy of Huli Jing, a mythological race known for using sexuality to confuse and utterly screw with humans.
Star Fox. Every prominent female character in the series when shown in full-body profile possesses breasts. Krystal is probably the most notable given the outfit she appeared in during her debut.
Mrs. Boggy in Banjo-Kazooie. One of the most blatant of the game's many very inappropriate (and thus hilarious when discovered) hidden references/images, most of which are 100% more subtle than... those. They're at least completely covered, but just look at her running animation and make your own decision as to whether you're supposed to notice or not.
In Guild Wars 2 the Charr females have no breasts, but one of the Anet Art Designers came out and said that the Charr Female were either going to lack breasts entirely, or they were going to have six.
In Nip and Tuck, most every female depicted of whatever species (apart from Hortense, a lizard) is amply endowed.
Sluggy Freelance hung a lampshade on this with the "Star Trek Adventure" where they meet an amazingly pneumatic Alien who is a male of his species.
The Whiteboard: Pretty much all of the regularly depicted female funny animals (all based on mammal species) are rather well endowed with human style breasts, which isn't treated in the comic as being unusual in any way.
Broken Plot Device, aside from the reptilians with breasts, has cats, rabbits, elaphants, rats, and other animals with boobs; with the largest pair owned by Sunny, a mole.
Animaniacs has Minerva Mink. When the DVD collections came out, Minerva's cleavage was... reduced from the original cartoons. Apparently, what was OK on broadcast TV at 4 pm in 1992 was a little too spicy for a DVD release in 2009.
The Amazing World of Gumball is a place where Everything Talks, and almost avoids this trope, with many of the females lacking all the Tertiary Sexual Characteristics. The exceptions seems to be Ms. Simian (a baboon) and Granny JoJo, who have very noticeable, sagging breasts, while Richard and Mr. Brown have rather sizable moobs (the latter is only visible when his fur is out of the way).
The Worldkillers from the New 52 plays this straight and averts it. Of the three members confirmed to be female, Reign and Perrilus have this, while Deimax has the biggest most masculine build of the lot, and except for the Non-Mammalian Hair, doesn't look female at all.
In Mario & Luigi, Bowser gets them after Cackletta takes over his unconscious body — on the outside of his shell.
All the various anthropomorphic races featured in the MUCK game SouthernCross. Almost all of the races are human, with a bad tempered Planet-God having tried to kill humanity by mutating them over and over until they died. It didn't quite work, and while a few pure human lines survive, "human" now refers to any anthropomorphic character not explicitly stated as Non-Human. Therefore they not only possess mammalian features that would not be at home on their apparent species, but are also reproductively compatible with other "humans" (but generally not with explicitly stated non-humans).
In Star Trek Online, all females use the same body model. This includes Andorians (who have some insectoid features, like a partial exoskeleton and antenna, and four genders, with the one that actually bears the young doing so in a fashion rather like marsupials) and Saurians (lizard-people, what else).
Explained away in Triquetra Cats with the Antreyui, descendants of humans who have been spliced with the DNA of animals, so they're not so much anthropomorphic animals but thereomorphic people. The lizard people and bird people may have reptilian and avian traits and features but they are still mammals.
NSFW Comix was doing a few comics with dinosaur-related puns, which he called "Dinosaurgy". In one, it shows an ostensibly female triceratops stripping with bare breasts. In the flavor text, he acknowledges that it's impossible since dinosaurs aren't mammals, and therefore, have no mammaries.
Jack uses this trope, as it includes insects, birds, reptiles and dinosaurs, all with breasts. Possibly justified, however, as all furries were created from human DNA. It's possible that the mammal/bird/etc classifications are just cosmetic. They even show a mammalian furry married to an insect "furry", with little big-eyed mammal kids with antennae. Oddly enough, they've showed such cross-breeds earlier many times in the series, without the explanation given until well into the story.
Mahoro from Mahoromatic subverts this nicely; She's a combat android and so big boobs would only be a hindrance. However on the battlefield of love she finds herself drastically under-armed when it comes fighting for the affections of her Master, so much so that she changes her wish for Earth peace to a wish for bigger breasts as well as asking for a modification from her creators at VESPER in a letter "home." It is promptly denied to a round of applause.
Cosmo from Sonic X. In a climactic moment near the very end of the series, she suddenly transforms from a child to a full-grown adult, complete with breasts and child-bearing hips... in spite of the fact that no other female of her species is portrayed with these. Furthermore, the scene comes complete with gratuitous close-ups of her swelling bust and posterior, which makes the whole thing more than a little bit worrying.
T'ra Saa, despite being a sentient plant, embodies this (possibly to avoid alienating readers when she's shown to be in a relationship with a human male). She's made appearances in Republic and Legacy.
Most 'female' robots in superhero comics get this treatment if only to identify that they are indeed female despite not having any need for breasts and only being considered a specific gender due to the person their A.I. is based on. That and Fanservice to anyone who's into that sort of thing.
Platinum a.k.a. Tina a.k.a. Platina is a robot built by Dr. Magnus creator of The Metal Men. She has the body of a centerfold complete with metal mammaries. Despite this, Dr. Magnus constantly berates her for "acting like a girl" despite obviously having made her in the shape of one. Dr. Magnus has issues. When the Metal Men appeared in the Superman/Batman series, Copper looks very much like a "black" (i.e. copper-colored) version of the "white" (silvery) Tina.
Films — Animation
A botched spell from Schmendrick in the film The Last Unicorn causes a nearby tree to sprout a female face and large breasts, with which it subjected the bumbling wizard to Marshmallow Hell. Possibly justified, as perennially-dateless Schmendrick's subconscious might've affected the magic's effects, and the tree did have a couple of suggestively-placed large boles on its trunk.
The Neti from the Star Wars Expanded Universe, though they at least are shape-shifters and implied to choose such things because they want to look more humanoid, so as to fit in better in a galaxy dominated by humanoids in general in and humans in particular. However, the Zelosians have no such excuse.
Played with in Feminine Intuition. The first couple models of the JN line play this straight, including metal breasts. The final JN-5 model, though, is just a little more delicate in build then a 'male', with a tapering waist and a voice described as liquid and musical.
Jabe, from the Doctor Who episode "The End of the World". Possible justification, as her race ("From the Forest of Cheem, we have... trees!"), may be half-human (one of the "mongrels" referred to by Lady Cassandra). The only stated fact of their evolution is that they are descendants of tropical rainforests transplanted from Earth five billion years earlier.
A borderline case comes from Star Trek: The Next Generation. The Borg certainly don't breastfeed, but allowed unit Seven of Nine to keep her fairly impressive set of functionless accessories. You would think the Borg would remove them as biological tissue takes energy to maintain, and thus reduces efficiency. Even less explicable are the breasts on the Borg Queen in the movie, but maybe that body was just for formal receptions. The Borg Queen only has her physical body created when she has need for it, after all.
Whereas the BIONICLE toys are, for the most part, aversions, the movie redesigns played the trope straight, even if subtly. The best example being Toa Metru Nokama, who did have a cleavage, with the top-part of her inner gears sticking out (these gears were less prominent on her male partners). Roodaka's are, in an interesting twist, less pronounced in her movie design. Allegedly her toy, although popular with fans, even caused complaining among certain groups for being so well endowed. However, Word of God says that even the males of her species are supposed to look exactly like her, though the only one we see is tiny and from the back.
Several female Transformers, including Arcee, Thunderblast, Beta, and all who are named Blackarachnia. (Most Blackarachnias are also at least partially organic... but they're spiders.) In one episode of Transformers Cybertron you get to see Thunderblast's "breasts"... jiggle. In another episode, she has nipples.
In the Transformers Prime series Arcee and Arachnid are both fully metallic (as this continuity drops the organic hybrid angle of past shows), but both still have breasts.
Botanica is a twofer: a plant that turns into a robot!
Transmetal Airazor was the first ever western Transformers figure to be designed as a female (all others were either aborted during the design phase or were conceived as males but retroactively had their gender changed), and naturally, she has these. She's also partially organic, but she's supposed to be a bird.
There's a large-breasted sunflower in Conkers Bad Fur Day. You need to pollinate her with the king bee to increase her bust size. Which you can then use as a trampoline. Apparently the dev team originally called them stamens, and then freaked out when, days before release, someone realised that stamens are the pollinator organ, not the pollinatee.
EDI in Mass Effect 3 has the largest chest of any female in the series, which is saying quite a bit. Supposedly her body was designed as an infiltration unit that passes itself off as a human, but there is no way anyone would mistake it for human.
In the MMO Wildstar, there is a playable race of robots called Mechari, and yes, the females have breasts. Mechari were specifically designed to be a race of Manipulative Bastards, and the more human they look the easier that becomes.
One minor subversion is Roll from the Marvel VS Capcom games. When she uses her Hyper Roll manoeuvre, she grows into a giant robot with good-sized breasts ... that launch as missiles. Repeatedly. She doesn't need to store milk, so why not some RDX?
Played with in Guild Wars 2 with the Sylvari, a race of Plant People. They are plants that mimic the human form for backstory reasons, including females with breasts, but they are not actually breasts in the mammalian sense and are non-functional in that role - they're simply plant growths that look like breasts.
A female tree-android, working at Namco Bandai, in Tekken Tag Tournament 2's ending for Mokujin (a male tree-android) sports a pair on her oddly shaped log torso. She's been around for a while; Mokujin started with a 'female' torso style in its debut in 3, with breasts and the best you could do to shape a wooden trunk into a dress.
In the Christmas SpecialChristopher the Christmas Tree, a number of anthropomorphic pine trees are talking about why they'll be the first to be picked. One has snow strategically placed to look like a boobs, and she even comments that she's "the fullest" while making her snowboobs jiggle. You can see this starting at 1:25.
Many fem-bots on Futurama fall into this category.
In the Downtown episode "The Con", Alex and Serena look at Robot Porn.
The Schoolhouse Rock character, Interplanet Janet, is half human and half spaceship but sports a pair of metallic breasts.
The Female Titan in Attack on Titan is named as such because it's the only Titan with visible breasts, despite Titans having No Biological Sex and lacking genitalia of any kind. What's more, because the Female Titan has no skin it's clear to see that its breasts are made of muscle, making them doubly useless.
The June 1953 edition of EC ComicsWeird Science featured a story called "Right on the Button" in which a man marries an alien woman who stabs him to death on their wedding night when she sees he has a navel, revealing that he is a (GASP!) mammal, born from a (GAG!) womb! But like all EC pretty girls, she has great tits!
In Archie Comics' Sonic the Hedgehog Salma and Juanita, the daughters of Espio, both have hair and, being older, Salma also has boobs. This could be explained by the gene bomb that mutated all life into what it is today in the comics. However, the cover of Sonic Universe #8 shows that Argyle now has distinctly different punk hair which, not only wasn't present in his initial appearance, is rare for any male character, even if they are a mammal (the only other male with distinctly different hair is Antoine the Coyote). Let's see the Xorda explain that one.
The Tymbrymi in the Uplift series have shape shifting qualities and as such usually don't have mammaries. If the necessity arises though features with the tactile feedback if not function of breasts can be acquired.
M.C.A. Hogarth's Tales Of The Jokka: Anadi Jokka have breasts, it's not entirely clear whether they are mammals even though they lactate, give live birth, and have hair, considering that they're aliens and have been known to change sexes during puberty.
In Discworld, trolls are basically vaguely humanoid piles of rock. In the novel Moving Pictures, Ruby the troll lounge singer is described as a cross between a stone age fertility goddess and a foothill. In The Art Of Discworld, Paul Kidby takes the reference to Venus figerines and gives her, in his own words, "a large rocky bust".
Doctor Who shows a Chimeron woman nursing her child... with a miniature power generator. Chimerons suckle on energy. So why do Chimeron women have breasts?
In Star Trek: Enterprise, Trip gets raped by a forehead-of-the-week and grows nipples on his wrists. The alien has normal humanoid breasts.
Star Trek: Voyager reviewer SF Debris pointed out the unlikelihood of Kes, an Ocampa, having breasts if her species actually existed in real life, since her species only has to mate once in a lifetime (Ocampa get plenty of foreknowledge of when that mating will take place so there's no reason to "fool" the males into thinking that the females are always fertile, and thus no reason for females' breasts to always remain swollen). Also, expanded universe material suggest that Ocampa give birth in multiples to keep up their populations' numbers, and yet, Ocampa only have one pair of breasts.
A cartoon in a long-ago issue of Playboy showed a landed flying saucer with a bevy of semi-naked, very human-looking, very voluptuous "aliens" surveying the area. Spying on them from behind a nearby tree are two human males, one saying to the other "That's nothing, wait until you see their females."
There's a frankly horrifying case in Darksiders with Tiamat—a dragon/aye-aye/scorpion creature with the head of the thing from Predator... and outlandish breasts.
In the MMORPG Earth Eternal the multitude of races, including demons, yetis, cyclopes, and robots, are different in much the same ways humans are. However, all of them, even those that look like birds or reptiles, are actually mammals created by the gods, and closer related to each other (and humans) than the species they resemble.
In Grim Fandango, every human character is a stylised skeleton, yet the females have inexplicable bulges on their chests. This is consistent with the Day of The Dead figures that the artwork is based off of, and somewhat justified because the characters are Calaca dolls, not real skeletons. Hence the oversized heads, the non-transparent interior, etc.
In Mass Effect 2, quarians possess mammaries, which are obviously visible in the shape of their survival suits, and at one point a quarian explains that "bubbles" are used when a child is weaned from nursing off their mother's immune system but before they get a suit of their own. In Mass Effect 3, if a male Shepard completes a romance arc with Tali, the picture she gives him shows that quarians very closely resemble humans, confirming that they are mammalian.
Cleanly averted with the krogans, whose males and females, the latter seen in Mass Effect 3, look exactly alike to a human eye (the females are distinguished by wearing what amounts to a burqa). Inverted when a krogan asks female Shepard if she's female.
"'Scuse me for askin', but — you're a female, right? You got those funny bumps, like an asari."
Speaking of asari, they prefer mating with other species instead of their own for additional genetic diversity. So, what does an asari need to attract a, say, human to meld with? It's even discussed ingame how members of three different species consider an asari attractive. It's also not unlikely that their breasts work as, well, breasts (i.e. for nursing.)
The Draenei are blue alien space goats, about as far removed from terrestrial mammals as you'd wanna get. And yes, the females have boobies. Orcs are alien humanoids as well, and also about as far removed from terrestrial mammals as Draenei, and their females get boobies too.
Some earth elementals and Titan creations have breasts as well. If the later can be hand waved as being replica of their creators, they are still made of rock or metal and don't even reproduce sexually.
StarCraft: Ghost development renders revealed that female Protoss have breasts, despite the fact that they are aliens unable to eat solid food, being purely photosynthetic. However, StarCraft: Ghost is not considered canon, and the Protoss females so far seen in the RTS wore chestpieces that weren't shaped in a way suggesting bulges underneath.
Female Forerunners of the Halo franchise have breasts. It's somewhat justified in that they and humanity were both created by the Precursors and are considered "brother species" by some, sharing many physical characteristic.
When Gabe, in Penny Arcade, gleefully remarks that an up-coming video game may feature boobs, Tycho gently admonishes him for thinking so pedestrian: "Imagine a Chik'thar hive maiden scuttling out of her mottled carapace. Her inviting, transluscent thorax heaving with ripe larvae. She retracts her guard plates, where forty alien breasts bristle with nipples... (eyes glaze over) Yes, yes, a thousand times yes..."
Lampshaded in the Sluggy Freelance arc "Years of Yarncraft", when Zoe points this out to Torg, Torg tells Riff how to tell which of the slimeblobs are female. Yep, it's boobs.
Dragons from Draconia Chronicles have a noticeable pair of bulges on their upper torsos. However, they're clearly beneath their hides. The author states they're actually "flight muscles".
In the What If? episode "Gwen 10", some of Gwen's female versions of the aliens have busts. Including the one that's essentially made of gemstone. This is even weirder, given than Gwen herself had yet to hit puberty. (The aliens Ben transforms into also seem way past puberty.)
Green-Skinned Space Babe Xylene, who sports an impressive set. She mentions that her species hatches from eggs. OK, maybe she's a Monotreme and would nurse them afterwards. Oh, but then she says that parents of her species do not take care of their offspring at all. Really?
Myaxx is pretty well endowed, seeing as her species seems to be extremely Squidlike.
Parodied in South Park's Heavy Metal tribute, appropriately entitled "Major Boobage." Everything in the various dream sequences sports an impressive set of breasts, complete with nipples. There are ostrich-things with breasts, planets that are disembodied breasts, and a trio of trolls with huge breasts growing out of their shoulders. The kicker? There is exactly one human woman — "and you never really get a good look at her boobs". Only her boobswere censored.
There is the Drawn Together twist ending parodying the first "Superman" movie, where Captain Hero changes history — and the evolutionary timeline — to make everyone boob-monsters that go around saying "Boob," Pokémon-style.
On Gargoyles, the title species comes in a variety of shapes from vaguely reptilian to mammalian, but females always have breasts. Word of God claims that however they look, gargoyles belong to their own class of animals called "gargates" (which descended from dinosaurs or similar creatures), and while they lay eggs, females do nurse.
Jamba!'s ringtone mascot "Crazy Frog", a.k.a. "The Annoying Thing", sporting ambiguous but noticeable genitalia that caused some controversy when he began appearing in late night ringtone ads. When he first began appearing in music videos in the United Kingdom, a prominent black bar was used to censor his groin area. With the exception of the tailed frog, amphibians don't even have external genitals.
Anime & Manga
In Dr. Slump, Obotchaman, a robot created by Dr. Mashirito, appears to have a penis, as seen when Senbei attached Arale's head on Obatchaman's body. Peasuke ends up walking in on Arale changing clothes, leading him to temporarily believe Arale was transgender. In the remake Arale shows it to Senbe while her body and Obotchaman's were swapped for a repairing purpose.
A man was walking through a pet store when a parrot called for his attention. "Buy me, I'm a very interesting parrot!" The man stopped and asked "What's so interesting about you?" "I have no legs," said the parrot. "Well how do you stay on the perch?" the man asked. The parrot replied "I have a very long penis and wrap it around the perch!". The man did think this was an interesting parrot and bought it. One day the man came home from work and the parrot said "Your friend Harry was over today!" The man said "Really?" "He was hugging your wife!" The man asked for more information. "They were kissing!" The man asked for more info. "They took their clothes off!" Infuriated, the man demanded what happened next. The parrot responded "I dunno, I got a woody and fell off the perch!"
In Small Gods, a tortoise who's really the god Om is lifted into the air by a chelonicidal eagle, but persuades it to deliver it to a specific location rather than drop it on a rocky surface. Its method of persuasion involves a hard beak and a solid grip upon certain delicate pieces of anatomy... anatomy which, as a bird, the eagle wouldn't actually have. (At least, not externally where they can be grabbed.)
In the Annotated Pratchett File v9.0, there's a bad joke cited in the Moving Pictures section about a toad with a troublesomely yellow penis. In reality, for a toad even to have a penis would be far more troublesome than its coloration.
In Petty Pewter Gods, Garrett tells a nosy hustler that he controls Mr. Big's chatter by tugging on a concealed thread that's tied to the parrot's little bird balls. Justified because the only thing Garrett's really yanking is the hustler's chain.
In American Gods, Anansi tells a story of how he tricked a tiger into swapping its tiger's testicles for his own tiny little spider testicles.
In Farscape, when Chiana, in a fight with a Scarran, asks, "Hey, do Scarrans have mivonks?" and then kicks for them... then winces and hops around, having hurt her foot. It replies that they do, but they're on the inside, and obviously well-protected.
Commander Strax was made into a nurse as punishment for being a failed Proud Warrior Race Guy. This apparently extends to being genetically modified into being the perfect nurse, including the ability to generate "magnificent quantities of lactic fluid".
In "The Curse of Fatal Death", the Master, in league with the Daleks, has been given by them a pair of "Dalek bumps" which take the form of two gold metal hemispheres on his chest.
Dreamwalk Journal: as noted above in the Insects section, it's about anthropomorphic insects and arachnids. All females have big boobs, all males have big external genitalia, and everybody gets to have sex with everybody else, including two visiting human women.
Gannji: And I don't need your standard-issue loincloth, I've been walking around without pants this entire time! It's called a "genital sheath," look it up. Hey, while you're at it, look up "hemipenes," because you can suck both of my—