Digimon meanwhile tend to vary. There are some seal, dog and wolf-like Digimons that plays this trope straight. Then we have evolved ones, who are anthropomorphic in build, that wear pants or shirt to cover their area (Angewomon, Leomon, WereGarurumon, LadyDevimon, etc.). And then there are some that are biped yet plays this trope straight (Zudomon, Renamon, etc.)
Averted in this instructional video about using the toilet where Shimajiro the tiger cub is actually drawn with visible genitalia when his pants are removed.
Averted near the end of My Neighbor Totoro where the Catbus is actually revealed to be extremely anatomically correct (and male) during the scene where he is shown running on top of several telephone lines while helping Satsuki and the three Totoros find her younger sister Mei. Played straight with the Totoros themselves however.
Lampshaded with The Vision in West CoastAvengers. U.S. Agent demands that he "show some decency" and put some clothing on, but Vision points out that clothing would be pointless since as an android, he doesn't have nipples or visible genitals.
The preservers in ElfQuest have androgynous bodies without genitals or nipples. Justified, as they're apparently asexual and sexless.
Bloom County: "No dice! Comic strip animals aren't anatomically correct!"
Particularly noticeable with Gus in Cinderella, because his shirt is so teeny-tiny on him.
Fievel in An American Tail is usually fully clothed, as are the other mice in the series, but in the brief nude scenes in which he's taking a bath he follows this trope.
Edmond in Rock-A-Doodle gasps and covers himself up after being turned into a kitten and realizing he's naked, despite not really having anything to cover up. He then "covers up" with a big shirt that still leaves his furry but otherwise featureless bottom half exposed.
Justified in Flushed Away during the Toad's Start of Darkness where the Toad actually does not have genitalia at all due to him being an amphibian.
Although Po from Kung Fu Panda is always portrayed as wearing only pants and nothing else, as seen in the flashbacks in the sequel, his baby form actually fits this trope.
Averted in the films based on Richard Adams' books Watership Down and The Plague Dogs. While the bunnies in Watership Down don't have any visible genitals (which is Truth in Television, as rabbit genitals aren't easily visible in real life), the dogs in both films have visible testicles and penile sheaths.
Films — Live-Action
Mystique, in the movie versions of X-Men, despite being human, is decent even while naked. This might be part of her shapeshifting (seeing as how she can look like she's wearing clothes too). Rebecca Romijn even lampshaded this by commenting that her character's costume was "strategically placed body paint, pasties, and clever camera angles".
The prawns of District 9 are hermaphroditic and thus self-fertilize. Despite that, interspecies prostitution is briefly mentioned.
Averted in Star Trek VI. While on the prison planet of Rura Penthe, Kirk fights an alien prisoner and kicks him in the middle of his legs, injuring it and causing it to wail in pain. Kirk remarks that he was "lucky that thing had knees." Another prisoner remarks, "That was not his knee. Not everybody keeps their genitals in the same place, Captain." Interestingly, the camera shows a detailed closeup of the art department's version of injured alien genitalia which is plainly visible through a tear in the alien's clothing (a tear which seems to exist for no other purpose than to allow us to see the squishy and unrecognizable alien goodies).
Averted in Wildcards with The Walrus, an alien undercover agent who looks very much like an anthropomorphic walrus. It is mentioned that it has quite peculiar genitalia (although not really described) and is a hermaphrodite.
This trope comes into play In-Universe in the Magic: The Gathering story "Dragon's Paw" by Edward Bolme. Urza magically creates a dragon to aid him in his experiments, but doesn't bother to give it a gender. The dragon talks him into making it stronger and bigger and eventually wants to be given a gender. When Urza admits that he's not sure how, the dragon convinces him to let it do the work - and uses this newfound control to sever the link between dragon and mage and flies off into the world.
In a fantasy/comedic novel from L. Sprague de Camp, the main characters summon a demon who's clearly devoid of genitals despite being otherwise human-like. When he's asked about the mating, he explains that the members of his race "grows" genitals in the right season.
When the Alien Autopsy was presented on Fox, they pixilated the part of the "body" where the genitals would be, if it had any. (And truthfully, it looked like it was lacking.)
The Asgard from Stargate SG-1. Justified, as they don't reproduce. When we see precloning Asgard popsicles, the relevant area is hidden behind the frost.
Naboo the Enigma from The Mighty Boosh is an alien, and reveals this about himself at Howard's birthday party.
Played with in the Farscape episode "The Flax." A male alien drops his pants to show the crew murals on his legs from being in prison. The crew lampshades this trope with Zhaan even saying "For an anthropoid biped, there seems to be something missing." This is later hilariously explained when the alien is revealed to be the female of her species and in love with D'Argo.
In addition to the page quote above, Londo Mollari also averts this trope by using his... *ahem* "attributes" to cheat in a poker game. Hilarity Ensues when one of the other players accidentally puts a glass of ice water down on the appendage in question.
In an early Dragon Magazine article, "The Psychology of the Doppleganger", a captive doppleganger's lack of genitalia or nipples in its natural form was openly discussed, as it provided its human captors with evidence (confirmed via interrogation) that such Dungeons & Dragons monsters had no true gender, and bred by changing into a gendered creature's shape and mating outside their own species.
Possibly Vortigaunts in Half-Life. Totally alien so anything goes, but a featureless crotch is good for the censors.
In Knights of the Old Republic, Rakghouls aren't shown with genitalia, despite being hairless and shiny. This is never addressed within the story, IIRC, even though rakghouls are humans transformed by The Virus. At one point, humans transform into Rakghouls in front of your eyes — their genitalia appear to have instantly disappeared (along with the eyes, and the fifth finger, and... A lot, really).
One of the few things that you can't give your Spore creatures is genitalia, although you can place body parts designed for other purposes where they should be.
The Sonic the Hedgehog franchise primarily features animals without clothing (or very little anyway, as they usually at least wear shoes and White Gloves), except in case of the females (and Charmy Bee, who wears an orange vest and a flight helmet). None of the male characters are shown to have genitals, thankfully. Even Charmy.
Very, very much averted with Satan in Dante's Inferno, where the attention to detail is far from subtle, probably to conform to some popular depictions of the character. (Oddly, in the pre-rendered cutscenes these critical areas are consistently obscured by shadows. Go figure.)
Played straight in both Super Mario Bros 3 and Super Mario 3D Land where the Tanuki Suit, unlike many traditional depictions of the Tanuki, is very anatomically incorrect. Justified since both games are supposed to be appropriate for kids.
Averted for several monsters in the God of War series. The gorgons and harpies have boobs, and in God of War 3 the centaurs have barely noticeable sheaths.
Both lampshaded and subverted in this strip of Buck Godot: Zap Gun for Hire. Buck, on the run from an ardent pursuer, drops into the rooftop garden of his best friend (and bartender)'s fiancé, Tal. Both she and her husband-to-be are Thuxians, vaguely resembling somewhat "softer" versions of the Xenomorphs from Alien. Tal was apparently sunning when Buck dropped in, and is thus buck-naked, which causes her to complain loudly about Buck's sudden appearance. He silences her, however, by pointing out that since humans and Thuxians are biologically incompatible, he wouldn't even know which parts of her could be considered "naughty". Then he comments on how her plump thorps bring out the sway of her tail,*
Averted in Digger: we don't see anything because it's not that kind of comic, but given Ursula Vernon DID do her research It is alluded to that The People (a race of sentient Spotted Hyenas) DO have pseudo-penises. As for Digger herself, It's hard to tell: She never wears any trousers, but given she's a female wombat, it's not like there would be much externally visible, or of interest to non-wombats, anyway.
The flying rats are either all female or suffer from this though.
Averted in favor of Scenery Censor with Crunch the troll in Dumnestors Heroes, who doesn't have enough fur to viably cover up the parts in question anyways.
Roger mentions to a date that he doesn't have any genitals. (It was okay; she had both)
In another episode, he claims it's just imperceptibly small due to years of steroid abuse
Bugs Bunny may have actually averted this trope in the short The Wabbit Who Came to Supper, during a scene in which he's coming out of the shower and his towel slips, revealing what looks like a white fur-covered penis for a couple frames. This has been discredited by most, though— it was most likely supposed to just be a gap between his legs and above the towel, through which either the bathtub or another part of the towel is visible. The animators at Warner were never above slipping things past the radar, though, so it isn't completely out of the question.
Averted in Retarded Animal Babies where Puppy is actually drawn with visible genitalia (even when he's wearing clothing), but played straight with the other Animal Babies.
Aqua Teen Hunger Force featured several relatively anthropomorphic food items, who all expressed sexual attraction to women (Master Shake likes to look at dirty magazines alone), but none of whom wear clothes or show their genitals.
The episode where Shake sells Meatwad to the circus featured the "prince of Saturn" (or was it Neptune?) sent to Earth to reproduce with our women. This one was a notable aversion, he revealed his genitals and they were horrific (and thus his mission failed), that's why he's running a circus now instead of still trying to take over the planet.
The original Crazy Frog video infamously averted this. It's a particularly strange case because actual frogs don't have visible external genitalia at all.
Regular Show: Oddly, Mordecai and Rigby are the only Funny Animals without some sort of clothes on. Rigby's brother Don (who's also naked but drawn with a MUCH more human-looking anatomy) lampshades this:
Don: Remember when you started walking around naked? I thought you were SO cool.
Brian from Family Guy has been the butt of several penis jokes, despite his own lack of visible genitalia. Brian claims it gets pulled inside when he stands up. Truth in Television; dogs have a sort of retractable penis on their belly that normally rests inside a sheath.
Even though Sponge Bob Square Pants showcases species that would not have external genitalia in real life and are shown lacking them, the male animal characters in the show have lampshaded this trope from time to time.
SpongeBob has been seen completely naked (well, completely naked except for his shoes) in multiple episodes. In "Spongebob Naturepants", Scenery Censor is used to cover that area most of the time, but it can still be seen a few times. In "Hooky", he is traumatized when Pearl and her friends (as well as the audience) sees his non-existent genitalia.
Patrick and SpongeBob become Invisible Streakers in one episode and terrorize the town. Mr. Krabs catches them and puts them on show before they have a chance to get clothes on. They try to use their hands to cover their nudity, but it is obvious they have nothing to hide.
Mr. Krabs is completely naked when Plankton uses a machine to switch lives with him (a variation on the Freaky Friday Flip) since Plankton is usually completely naked. Even though it is obvious that he has no genitals, Plankton is still mortified to see him in the nude.
Sally Acorn in Sonic the Hedgehog comics (and the Sonic Sat AM cartoon) can be either fully nude save for boots, or wear only an open vest. Either way, she has obvious breasts without nipples.
Averted with Commander Vachir from Kung Fu Panda, who is a rhinoceros with visible nipples on his bare chest.
Moto Moto the hippo from Madagascar: Escape to Africa has this.
Played with for laughs in Ice Age III. Scrat is a saber-toothed squirrel...thing, and is presented with neither visible genitals or nipples. Until a patch of fur gets ripped off his chest, revealing two nipples on the skin underneath. The female Scratte plays this straighter, with the impression of having breasts, but once again no visible nipples.