Leo: "It's about those alien face-huggers. They clamp to your face and implant their babies into your stomach, right? [...] Wouldn't that mean they stick their, you know, down your throat?" Aeris: "OH MY GOD! They're raping your face! That's horrible!" Leo: "I tell ya. As if killing you isn't bad enough. You also get a face full of alien wing-wong."
A creature reproduces by impregnating another species. This can be a very literal pregnancy, a rearrangement of your DNA, or it could be the implantation of a parasitic egg or larva into the body of a host of either gender.
May very well lead to a Chest Burster.
The Real Life scientific term for a creature (usually an insect species) that does this to other species is a parasitoid.
A subtrope of Orifice Invasion. See Anal Probing and Boldly Coming for more alien on human action. See also Mars Needs Women. Despite the name given to the trope, the impregnation does not have to occur via the face of the victim.
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Anime and Manga
Berserk, being a series where monster-on-human rape happens on occasion, has not shied away from this trope. The Trolls that Guts and crew encounter in the Qliphoth reproduce by impregnating captured women. The births kill the mothers in horrific fashion as the new trollsnote only one "birth" is seen, but there were at least six of the little things rip their way rather gorily out of the mother's belly.
Humanoid Szayel Aporro Grantz does this in Bleach, thanks to his Naughty Tentacles. He impregnates the victim with himself, being "reborn" fully grown upon death. Believe it or not, that's not the most squicky part of this scene or its aftermath.
The diclonii from Elfen Lied (who are otherwise sterile, with one exception) 'reproduce' by infecting humans they encounter with a virus containing the genomic information of diclonii. Although it has no overt effect on its victim, the virus alters its reproductive cells, resulting in that every child born of an infected parent, regardless of whether the infected was male or female, will be a diclonius.
Oddly, when they infect human hosts, they stick their invisible 'vector' inside the head of their victim. They're supposed to be messing with the pineal gland, which actually had to do with sleep-cycle regulation, but which New Age types believed to be involved in psychic powers.
All Diclonii born from this mechanism are sterile "soldiers" who tend to have more and longer vectors, while the regressive-trait full-fledged ones like Lucy can still have children. But unless they have them with other full-bloded Diclonii, the children produced lack the powers of their parents.
Franken Fran provides an example with a female creature, "Azusa" the mutant mimic octopus, but the results are just as unpleasant for the human.
The chimera ant king in Hunterx Hunter is supposed to mate with the female of another species, turning her into a chimera queen ant somehow (or making her give birth to one, the manga simply mentions it'd "create" a queen). After the death of the former queen (the King's mother), chimera ant generals also gain this ability (becoming lesser "kings").
The same manga also featured a character who had a colony of leeches living in his tongue (which looked like a turtle cloaca, for extra gross-out points). The leeches burrowed into the victim's wounds and laid their eggs in the bladder, hatching a few days later and evacuating through the urethra. The pain is so agonizing it kills the victim.
One breed of mushi in Mushishi has the ability to enter a soon-to-be-pregnant woman and take over the body of her unborn fetus. The "child" that's born months later resembles a slime-like creature that slips under the floorboards of the parent's house. It begins spawning humanlike offspring that the parents unwittingly take care of. These "copies" age much more quickly than a human child, and once enough of them have been born, they enter the next phase of their reproductive cycle, wherein they 'die' and scatter their seeds. (These mushi children also possess human intelligence, making them far more dangerous than other forms of mushi, as Ginko, the main character found out.)
Rental Magica has a variety of Cordyceps (see Real Life section) which grows on humans in early stage of development. It's rare, so its cultivators contract suitable people as hosts (and plant it on themselves for that matter). However, its requirements as a parasite are negligible and it has no side effects worse than making host's hand look weird. It's more dangerous that it's a strong material component for necromancyandon the last stage of a life cycle destroys magical barriers—including ones preventing its detection.
Yu-Gi-Oh!: Parasite Paracide could be considered to fit this in the anime, at least Joey's Panther Warrior has gotten infected with it, leading to some parasite wing wong coming out of its mouth.
X-Men has an evil alien race called the Brood that fits this trope. They are basically very large insectoids whose queens lay their eggs in sentient beings. The Brood embryos not only transform their victims into Brood, but they also absorb their host's abilities. Thus, if a host has super-powers, that Brood will have them. The X-Men only avoided this fate by freeing the Acanti, a race of Space Whales enslaved by the Brood, whose shaman magically killed the embryos growing inside them in gratitude. It was too late to save Professor Xavier, but that's when having an alien girlfriend who owns a cloning tank comes in handy, as well as having enough psychic powers to transfer your mind into the clone.
A throwaway line in Buffy Season Eight indicates that a slayer who'd been impersonating Buffy had a magical version of this implanted in her by a creepy fairy.
A Future Shock in 2000 AD had a drunk guy narrating his woes to a barkeeper. Apparently a super-space-uber-wasp turned up at his office one day to tell him that he'd been selected as 'brood parent' for the wasp's eggs. The wasp also explains that the eggs are implanted through(!) the skull, and the larvae would eat their way out later, and would he mind holding still for a few seconds. The guy objects, and runs for it; uber-wasp chases. 30 or so panels of chase through an office block later, the wasp catches him after he jumps off the roof. End of flashback. The reason that he's in the bar is that he's trying to kill the eggs with elevated blood-alcohol before they hatch...
At least it was polite...
The Grant Morrison comic The Filth plays with this trope through the character of a Pornomancer called "Tex Porneau". Porneau uses the black semen(!) of Dutch posthuman pornstar(!) Anders Klimaxx(!) to create giant magical flying death-sperm(!) which are unleashed to fatally attack any creature with a uterus.
One story in an issue of the Futurama comic had Captain Zap Brannigan really enjoying being treated like a deity by a tribe of insect-like aliens. They catered to his every whim and fed him constantly, leading to a huge weight gain. It turned out he had been pumped full of their larvae and was acting as a living incubator. In the end, the crew of the Planet Express Ship managed to rescue him and extract the larvae, which looked like brine shrimp. Bender made a stew out of them and served it as dinner. Only Dr. Zoidberg was willing to eat it.
The prequel, Prometheus, naturally features Noomi Rapace's character giving birth to a squid-like prototype Facehugger, that ends up tentacle-oral-raping the Engineer, who then gives birth to a prototype Alien.
Subverted in The Host, when it really looks like the monster is laying eggs in people's skin or something, and the hero mentions that he feels something moving around in his skin. It's just his imagination, it turns out.
Feast had a scene which took the trope's title 100% literally.
The hellhound creatures known as Sammael in the Hellboy film sting their victims with a barbed pod at the tip of their tongues, which contains a parasitic infant sac meant to grow, devour its host, and grow into an adult demon. Hellboy was not pleased with this.
The comedy/horror movie Slither has slugs (really damn fast slugs) that jump into people's mouths to turn them into zombies. It also has a tiny seed thing that shoots a hick, turning him into an alien king that impregnates humans with two Naughty Tentacles, turning those humans into giant swollen balls of sluggy nastiness.
At the climax of SpliceDren, now a male, rapes Sarah, and as the twist ending Sarah is revealed to be pregnant and making a deal with the company she and her husband worked for to carry it to term for further research.
Demon Seed featured a woman being impregnated by her obsessed computer-controlled house.
In Jo Clayton's Irsud, book 3 of Diadem from the Stars, Aleytys was sold to a insect-like species to be used as the host for their next queen, which would consume her as time passed; Aleytys' abilities made her particularly good fodder.
The Wraeththu, from Storm Constantine's eponymous series, reproduce by injecting their blood on a human male, who then transforms into one of the androgynous anemone-penised mutants. Optionally, they can just have "relations" with a human being...but in that case, their "secretions" would prove fatal to the human.
The lubbocks in Diana Wynne Jones's House of Many Ways reproduce by laying their eggs in human hosts. Males infected this way simply die when the eggs hatch, but females give birth to purple-eyed Always Chaotic Evil creatures called lubbockin. As it turns out, the mysterious disease infecting the hero's uncle is that he's been attacked and "impregnated" by a lubbock.
In Stephen King's Dreamcatcher, exposure to byrus, a moss-like alien substance, occasionally causes humans to be impregnated with a serpent-like creature called a byrum. It spends a few days or hours in the victim's intestine, growing and eating the poor victim from the inside, after which it makes its exit through the anal orifice, killing the host in the process. Side-effects of having a byrum growing inside you includes a bulging, pregnant-looking abdomen, frequent chemical-smelling flatulence, and telepathic abilities.
Implied in The Dunwich Horror, in which the invisible monster terrorizing the town and Wilbur Whateley turn out to be the sons of Lavinia Whateley and Yog-Sothoth.
In The Shadow Over Innsmouth, the "Third Oath of Dagon" requires someone who swears it to marry and have children with a Deep One fishman. The kids start out human, but slowly turn into fishmen themselves as they age. However, some citizens just swore the First and some the Second Oath. The Third Oath was reserved for the people who wanted most in return, and were resistant enough to Squick. Zadok Allen mentioned that he had taken the First and Second Oath, but wouldn't take the Third even if they killed him. Considering that he had already lived decades like that, it doesn't seem that the Third Oath was compulsory.
This story was adapted for the screen as the film Dagon, which is the name of an entirely different Lovecraft work. (Interestingly enough, the "damned village" in the film is in Spain and renamed Imboca, which loosely translated means "In mouth", but we digress.)
A short story by Robert Sheckley features a race where the females implant the eggs inside males during sex (otherwise completely human), forcing them to spend 99% of the time in hibernation while the kids develop. Not surprisingly, the females have to travel around the universe looking for suitable hosts - their own males all ran away.
Bloodchild, a short story by Octavia Butler: Human hosts (almost always male) act as incubators for eggs of the female aliens, who look something like human-size centipedes. If the host is lucky, the mother gets to him in time to extract the newly hatched larvae before they eat their way out. This relationship is presented as symbiotic; the aliens cherish the human families from whom they select their hosts.
Anne McCaffrey wrote a short story called "Horse From A Different Sea" for her collection Get Off the Unicorn. The gist of the story is a small town doctor notices that a large number of his male patients are having odd symptoms like nausea, weight gain and unusual cravings. The men have nothing in common but visiting a "house of ill-repute". After running every test he could think of the doctor finds out the men are pregnant and that the "ladies" have vanished along with the house they were in. It was done with very little horror.....given the subject matter....
Puppeteers from Niven's Known Space novels reproduce this way, although they only use a species of nonsentient (we hope!) herd animal from their own planet as hosts.
In Snuff, Igor describes a tropical weevil that's been known to lay eggs in people's brains, entering through the ears and then exiting the skull via the nostrils.
David Eddings of all people briefly touches on this trope in one of his Malloreon books where a demon lord has impregnated a woman with obscene results. Polgara bloodily terminates the abomination.
Warhammer 40,000: the psychneuein, a wasp-like warp creature, infested Prospero, the homeworld of the Thousand Sons, until the natives' psychic powers evolved in defense. They could infest unprotected psychic minds with their eggs without even making physical contact.
Live Action TV
This is how the Magog reproduce on Andromeda. Harper once got an intestine full of mini-Magog that required Applied Phlebotinum to remove. For a while he still had them, couldn't get rid of them safely, and so had to take a drug every day to keep them from growing that would not work forever (perhaps a protease inhibitor metaphor). They could be removed with surgery, but considering the process nearly killed a genetically enhanced ‹bermensch, the typical person probably wouldn't survive.
Though they were demons, not aliens, the AngelMonster of the Week Skillosh in the season two episode "Epiphany" impregnated Cordelia by injecting their spawn into her skull after stabbing her head with a tongue stinger. Interestingly, this was actually the second time this happened to her, the first being in the season one episode Expecting, where she had conceived a set of demonic septuplets the, er, usual way after a one-night stand. In both cases, the pregnancies were mystically terminated.
Cordelia: I want you to find me a dimension where some demon doesn't want to impregnate me with its spawn! Is that just too much to ask?
Ironic given that giving birth to Jasmine caused her death.
The Adipose from the Doctor Who episode "Partners in Crime" might be the most adorable example ever. The Adipose themselves are an innocent and benign version—being sentient fat, they traditionally breed from other sentients' fat. However, there is a prohibition on doing this on planets where the natives have yet to achieve interstellar travel—including 21st-century Earth. The villain of the episode violated this, using "diet" pills that converted human fat into newborn Adipose, the birth rate of which would be increased to fatal levels by converting organ and bone.
Fringe, episode "Unleashed". Charlie is attacked by a genetically-engineered creature with a sting that's believed to be poisonous. Then it turns out the sting isn't poisonous, but a means of finding a host for the creature's larval young.
In Stargate SG-1, the Jaffa have symbiote pouches that are used to incubate the larval form of the Goa'uld. They are dependent on their symbiotes to carry out the function of their immune system. In a season 1 episode, Daniel Jackson was raped by the Goa'uld queen Hathor to harvest DNA to make her larvae better adapted to incubation by humans from Earth. Jack O'Neill was given a symbiote pouch to accommodate one of these (though, as stated by Dr. Frasier, "nothing got in there"). Not to be confused with the implantation process, during which a mature symbiote takes over the central nervous system of a host by entering the back of their head. The Tok'ra go in via the mouth, because they're only sharing the body and it's far more consensual — well, except for Jolinar and Sam Carter... (That one's been argued by the fans as a misunderstanding on the part of Jolinar, who was thinking that Sam wanted to be a host-and let's face it, he/she was desperate at the time.)
Also in the season 2 episode "Bane", Teal'c is infected by a mosquito-like alien and starts transforming into more mosquitoes. It takes both his symbiote and an antidote to cure him.
Lampshaded in Stargate Atlantis episode "Doppleganger" where one character has a dream about a chestburster and then the characters sit around discussing the movie "Alien".
Star Trek has gotten much mileage out of this trope:
In the TNG episode "The Child", Troi is impregnated by that week's cosmic entity and gave birth within a matter of days. Naturally, the child (the entity itself) causes the episode's Negative Space Wedgie just by existing.
In the Star Trek: The Next Generation Episode Identity Crisis, Geordi and several of his former crewmates are metamorphosed into invisible feral aliens after being infected by a parasite on the planet Tarchannen III they were surveying several years before.
The Enterprise itself became a victim of this Trope in Emergence. At first it seems the ship is becoming sapient.It turns out the Ship had been "impregnated" and "gave birth" to a strange construct that floated away into space
The Enterprise episode "Unexpected" had Trip unintentionally impregnated with an alien embryo after putting his hand in a box of "pebbles" at the same time as the Alien Babe Of The Week.
In the Torchwood episode "Something Borrowed", an alien transfers its spawn to Gwen via bite the night before her wedding. It's then up to Torchwood Three to inelegantly teleport the fetus out of her before its biological mother comes to rip it out.
One of the creepier monsters of the Creatures section of the Urban Arcana setting for d20 Modern is the Roach Thrall. Only thing nastier than seeing one shed its human skin to take on its true giant cockroach form is the way these things reproduce — they use the sexual organs of their human hosts to implant their eggs into a human, and when the eggs hatch, the new roach thrall eats the victim's brains and internal organs while they're asleep, then takes over the body of its new host and blends into human society until such time as its own eggs are grown and it's time to seek out a new host to implant the eggs into.
Mind Flayers from Dungeons & Dragons take this a step further: in addition to requiring humanoids to be implanted by Mind Flayer larvae in order to reproduce, they also need to eat brains (between 1 a week and 1 a month per flayer. They only need the latter to survive and be quite safe from starvation, but the Illithids are jerks, so they prefer the former.)
It's interesting how only humans, not other "player character races", are suitable for making true illithids. Attempts to transform other humanoids or other creatures usually fails fatally, or the creature becomes something only sorta illitha-like.
This was retconned. In Lords of Madness, it's stated that ceremorphosis is primarily done on captured drow, who they share the Underdark with.
Red Slaad implant their eggs in unfortunate victims, killing them if they manage to hatch, driving them crazy beforehand. Blue Slaad carry a disease that mutates their victims into Slaad.
Phaerimm: Come along quietly, and you will live. Aubric: I doubt it. Phaerimm: Do not. I have a fondness for you brave ones. You hatch strong larvae.
Morkoth (kraknyth), aquatic vaguely cephalopodic sentient creatures that lay eggs in living victims. Even morkoth mages gives "pregnant" females a wide berth and clutch a weapon when in Under Fallen Stars; the process is depicted in detail. It ends with magical healing of the wound the ovipositor left, but by this time the hosts have reason not to be very happy about this.
Khorrch: Even should you live after the young hatch inside you and eat their way free, you would only be reimplanted with eggs or killed outright.
Dungeons & Dragons also has a monster called the Vargouille, which looks like a ghoulish, undead, humanoid head with leathery wings for ears and jagged teeth. This monster reproduces by paralyzing and then 'kissing' a victim, which causes a curse that slowly makes the victim's hair fall out, followed by their ears turning into wings, then they slowly lose ability points, until finally the head takes flight and simply removes itself from the body as another Vargouille.
Vargouilles are based on several mythological monsters (most notably the South American chonchon and the Malay and Filipino penanggalan and manananggal), all of which have had similar habits attributed to them.
Xill (inspired by Ixtl) are four-armed quasi-humanoid extraplanar creatures with a special ability, Implant. The xill grapple and pin an opponent then paralyze them by biting. Then, they implant eggs. The larvae will eat their way out if not removed. Surgically removing them will be nearly as traumatic.
Ekolids are literally the demonic incarnation of people's fears of infestation. They live up to it, too; they have six stingers which can implant ravenous larvae, and their mere presence drives people insane with hallucinations of biting insects.
Ravenloft, naturally, jumps on this trope's bandwagon, with red widows (shapeshifting giant spider/redheads who seduce human male egg-hosts), death's head trees (implanted seeds in lieu of eggs), and sea spawn (which combine this trope with Body Snatcher).
The Genestealers from Warhammer 40,000 have a slightly more insidious method: They implant their DNA into the victim, in a manner similar to Species. This doesn't result in the conventional hybrid offspring, instead acting more like The Corruption: the victim is compelled to love and adore the infecting Genestealer (also known as the Genestealer Patriarch or Broodlord)... and to spread the infection. This not only means luring new victims to the Genestealer for implantation, but also to seek out humans of the appropriate sex and breed with them. All of the children produced with at least one tainted parent are essentially Genestealer hybrids, which grow more human looking up to the 4th generation- which then produces pure Genestealers with anyone they breed with. This eventually leads to the formation of an entire cult of hybrids that seek to ensure that the planet they're on loses the upcoming Bug War they're inevitably going to call down on their heads. Making it even more insidious is that the cultists often know full well that they're next on the menu. Shades of Village of the Damned. Especially because the psychic web of a Hybrid Cult means that each person truly loves and adores even the most bestial-looking of their "family".
See the above-mentioned short story titled "The Shadow Over Innsmouth" by a certain H. P. Lovecraft that this idea also seems to mimic. Since the details as it relates to this are unexplained above: essentially, an entire village in the Northeast United States is breeding with an ancient underwater Elder God (and spawning hybrid offspring) attempting to bring down who-knows-what kind of calamity upon the planet. (The 'hybrid offspring' thing is beyond our human comprehension to understand why or how it works.)
Said calamity is never described by Lovecraft himself, but wider Mythos canon (including the Chaosium RPG, which is why it might not sit well with HPL purists) generally assumes the ultimate goal of the Deep Ones to be waking Cthulhu itself. To further the 40K parallel, this would essentially amount to an Exterminatus for humanity.
Nearly half of the various creature species in the GURPS sourcebook Creatures of the Night need humans as a component in their reproductive cycle in one way or another.
Changeling: The Lost: I bet you think there's some entry on a particularly nasty hobgoblin here, huh? Nope. This is why the True Faeactually abduct changelings. See, once a changeling's connection to the Wyrd reaches its highest level, their Clarity manages to drop at an exponential rate — mainly because whenever they dream, they remember Faerie perfectly, which means they have a trigger condition every time they go to sleep. And when a changeling hits Wyrd 10 and Clarity 0... they become one of the True Fae.
This isn't normally done specifically for the purpose of procreation. On the other hand, unwanted pregnancies aren't unknown among humans either.
The Broos, beastmen in RuneQuest procreate by rape. They can and will mate with anything, but the chance of this actually resulting in a living Broo... larva is greatest if the victim is a still living being of suitable size. Hence, most Broo look like goats, deer or antelopes on two legs, since capturing a herbivore like that and impregnating it is easy, but there are Broo born of various humanoids, huge predators like dinosaurs, and, well, rocks.
Not to be outdone, the New World of Darkness gives us Cymothoa Sanguinaria, cousin to the real world Cymothoa Exigua. Congratulations! You have a parasite living in a hollowed-out pocket under your tongue. It will influence you to seek out other infected hosts so it can be fertilized (the phrase "during a kiss, the parasites will copulate" comes up). Then it will lay its eggs in your esophagus and encourage you to kill people and drain their blood to feed the eggs. And it all goes downhill from there.
In the end, the lesson we learn from parasites is that we're all flesh, we eat, and we are eaten. Everything else is just meat, singing to itself in the dark.
The Thing From The Deeps in the Hunter: The Vigil supplement "Horror Recognition Guide" is a very unpleasant tentacle demon that kills people in order to reproduce. After it's killed, the hunter responsible finds himself being followed by creepy individuals who don't seem fully human and keep glaring at him with eyes full of hate.
Exalted gives us a few Yozis with powers like this. Kimbery represents motherhood in all its positive and negative aspects, and since she's lost the ability to sire children herself (due to the fact that her main form is an acidic ocean), she's got the ability to infect others with her own mutant youth and have them undergo the joys of childbirth. Metagaos, meanwhile, is a swamp that devours everything, including space, time, color, and health - which means that even if you survive a trip through his depths, you'll be bearing something that will make you wish you hadn't.
Darkseed starts the game by implanting an alien embryo into your skull. You have 3 days in-game to get it fixed or it will hatch and herald the alien invasion. Fun.
The Excuse Plot of the Duke Nukem game series has one definite point, which is that the alien invaders need human women's uteruses to serve as breeding machines for their species. The result, of course, is that Duke frequently stumbles on breeding pods: naked, writhing, moaning women wrapped in vine-like cocoons begging Duke to kill them.
It's all a very, very obvious Shout-Out to Aliens; episode 4 of the Plutonium Pack (or Platinum Edition) even features aliens that look like Xenomorphs. Also, there are aliens similar to facehuggers that will jump on the player character (thought they only drain his health, not infect him with a chestburster.)
Taken to a literal point in Duke Nukem Forever where they actually reproduce by depositing their "load" in the women's mouth as their underwear is still intact when Duke finds them.
Las Plagas in Resident Evil 4 generally live as parasites with the tendency to mutate their hosts, but after a point in the game, the player runs into Plagas who can live independently. Their method of exit has been well-documented, but their method of entry seems to have varied: first as spores, then later via injection.
There's also the parasites that the mutated One-Winged Angel William Birkin implants into people (Ben in Leon's 1st scenario, Chief Irons and Sherry in Claire's 1st scenario), which burst out of their victim's chest Alien-style, then metamorphose into a creature that resembles a Xenomorph. It manages to infect a corrupt Umbrella worker in Resident Evil: Outbreak, too.
Actually that only happens to people who don't share similar enough Dna, for instance Sherry would've mutated into a monster similar to him if she hadn't been cured.
Look no further than the Flood. And you get to see it happen in real time in the third game.
Closer to The Virus, given that the Flood parasites tend to take direct control of the victim's body, rather than use it solely to incubate new Flood. The actual mechanism of infection can definitely follow this trope, however.
In Sid Meier's Alpha Centauri, the Mindworms are a bunch of worms that gather up in huge boils, stun their victims with psychically-induced fear, and place their ravenous larvae on their skulls. Needless to say, the resulting death is Horrible, with capital H.
The plot of the first and third Silent Hill games revolve around this trope being implemented by an Eldritch Abomination instead of aliens, although it is no more pleasant to the host.
In The Sims 2, human male sims can be abducted and impregnated by aliens if they use the telescope during the wee hours of the night. Females can also be abducted, but won't be impregnated.
The Sims 3 Seasons brings back that option, and unlike in the previous game where the babies were hybrids of the aliens and the Sim parent, the child will be a pure-blooded alien. With Psychic Powers.
The Zerg in StarCraft are already partly based on Aliens, so naturally they get in on the act with the Queen unit, which has a special ability to fire a spore at a ground unit, which destroys the unit when two small Zerg hatchlings pop out of it. Very effective when used on a siege tank's pilot in the middle of other siege tanks.
Chryssalids in X-COM. Very fast acting, too, as all it takes is one bite from them and then a few non-fiery shots to hatch. Even the 'zombies' that are unhatched Chryssalids can kill unarmored units with ease. Thankfully, they're a terrorist unit for the mid-game Snakemen, so they don't show up very often and you should have sufficient tech when you do meet them. Still doesn't prevent them from being a great source of Paranoia Fuel, which becomes unleaded in a hurry during Snakemen terror missions where they can infect Innocent Bystanders and increase their ranks with you being unable to do a thing about it.
The rapid development is Hand Waved as a characteristic of the species. However, when a zombie is a destroyed, the egg inside supposedly hatches early, resulting in... a full grown Chryssalid. This is furtherHand Waved by stating that the resulting "early birth" Chryssalid is substantially weaker than a normal Chryssalid, but use of the stat-scanning device reveals that they are... a full grown Chryssalid.
The Tentaculat replace the Chryssalids in X-Com: Terror from the Deep. They're limited to underwater missions but that's where practically the entire game is. They're worse than the Chryssalids in that, since they can swim, they can come at you from any direction. There's one bright spot though, there are no underwater Terror Missions, so they'll never have any Innocent Bystanders to multiply with.
Slightly different are the Brainsuckers from X-Com: Apocalypse. They're small and have a very short lifespan, but have the nasty habit of leaping at an unsuspecting agent's face and injecting them with alien microbes which take over the host's body.
In the reboot, Chryssalids now no longer hatch if a zombie is killed. Instead, if you wait for 3 turns before killing the zombie, a Chryssalid will be birthed (rather messily) with its host being torn apart from inside. If you kill the zombie before the Chryssalid is born, then there will be no new Chryssalid. Problem is, however, is that Chryssalids are now much more mobile, easily infect civilians where you can't reach them, and zombies are often even stronger than Chryssalids.
According to another wiki devoted to the Monster Hunter games, the Khezu reproduces this way, by paralyzing another creature and injecting its young whelps into the unfortunate victim. The whelps live off their host until it dies, or they grow strong enough to leave. You can find Khezu whelps and deliver them for money, but while you have a whelp in your inventory it will constantly bite you, slowly draining your health till you get rid of it.
While their isn't any evidence the Headcrabs of the Half-Life series use their hosts for reproduction, they fit this trope almost entirely otherwise, commandeering the nervous system of a viable host and using it for their own purposes, with the whole experience being very unpleasant.
However, the new types of headcrabs introduced in Half-Life 2 (and their attendant new zombie types) include one that apparently DOES use the host body to reproduce, then FLINGS THE OFFSPRING AT YOU.
In Aliens Vs Predator 2, a facehugger jumping on your face quite literally shows this. The entire screen become the alien's underside with a very phallic tube swinging around in front of your face, implied to be going in your mouth (which can't be seen, since it's an FPS). It's instant-death, and after you see the "wing wong," the game cuts to your body laying on the floor, where you see your chest swell up, your body convulse, and an alien pops out.
In Dragon Age: Origins, it's implied that the Broodmother in the Deep Roads was the result of Darkspawn violating a member of Branka's exploratory group until it spread the taint into her, then force-feeding her their own flesh so she had enough mass to birth more Darkspawn.
In Kingdom Rush Frontiers, there's a enemy called the Parasyte (which looks like a purple headcrab spawned from a xenomorph egg). These will latch onto the faces of your soldiers and drain their health. Once the soldier dies, a deadly insectoid alien called a Reaper bursts out of them. These can attempt to infest a Necromancer Tower's skeleton, but no reaper is formed when the skeleton dies.
In an early Sluggy Freelance arc, the character Aylee is born in this manner, parodying Alien. Only instead of facehuggers, the alien species uses a technique that prompts the cry, "Get me a proctologist!"
Later, another member of Aylee's species takes a humanoid form so as to impregnate human females with new drones (it's implied that it's consensual, though even Aylee's disgusted).
In Fans!, Rumy is impregnated (along with a host of other artists) in a slightly more benign manner: The Energy Beings make her head swell up for a few hours before a floating, glowy fetus emerges.
In the Black Comedy web cartoon Stickman Exodus episode 'Sex Ed,' this trope comes into play with (sketchings of) giant flying sperm, appropriately enough, attacking one of the stick figure protagonists.
Whateley Universe example: in the story "The Op", the mutant semi-military team known as 'The Grunts' takes on a ruined city where something has invaded. They find a building with a Womb Level and some chambers where women have been given this treatment and are encased in tubes in the process of giving birth to monstrosities. Then things really go to hell.This is Sara if she stopped holding back.
On the adoptable pet website Valenth, there's a series of creatures called Leupaks, who all produce eggs. Including the males. And they can only have children by implanting them in another creature, which the egg will absorb various traits of, so when the egg hatches (and claws out of your body, Alien-style), it will be a whole different creature, in a way. Oh, and they implant them in your body by using a long, flexible tongue with a claw on the end. Squick much?
AnotherCracked article on how animals are evil]]. And yeah, the Sacculina and a species of wasp are mentioned. The Emerald Jewel Wasp goes above and beyond other wasps in pure sadism. It doesn't just paralyze the poor roach, it turns it into a zombie slave, cuts off its antennae to drink fresh roach blood, leads it back to its burrow, and then goes back to step 4. All to avoid the trouble of physically dragging it back. Good thing the venom it uses to shut off dopamine production in the roach (thus turning it into a "zombie roach") doesn't work on humans.
Roger on American Dad!gets Steve pregnant by accident when Steve gives him CPR since Roger's species reproduces through mouth to mouth contact. Strawman conservative father Stan takes him to Mexico - "God's blind spot", he calls it - to have it aborted. Steve keeps it, but it's transferred to his girlfriend via kissing. The girlfriend, having been raised by Stan's even more conservative rival, thought that was how pregnancy happened anyway, so she never caught on.
Ben 10: Alien Force'ss Mooks are DNAliens, creepy tentacle creatures who are revealed to be kidnapped human victims who have been taken over by an alien brain that latches onto their face and eats their DNA from the inside out. Rather dark when you consider the heroes kill dozens of these guys each episode, the Big Bad already has hundreds of thousands working for him, and it's stated that once someone is fully corrupted, their human mind is dead.
They're rather easily reverted back once the resident Gadgeteer Genius studies the Omnitrix's genetic repair function and makes instant-healing guns. A more bizarre version is when Ben's Big Chill transformation asexually reproduces and causes Ben to have black-outs and a huge appetite for metal whenever he turns into Big Chill. The offsprings produced by this condition are oddly adorable baby moth-people that promptly leave at the end of the episode. Ben is mortified that he's given birth, but his girlfriend finds it endearing.
Reversed in the Futurama episode "Kif Gets Knocked Up A Notch", where a (male) alien is impregnated by skin contact with a human.
In an episode of Jimmy Neutron: Boy Genius, Jimmy's friend Carl is impregnated (in the butt) by a flying alien Electric Jellyfish. It's "born" by static electric discharge from the behind, but is otherwise fairly harmless.
Marge: (voiceover) I tried to resist, but they applied powerful mind-confusion techniques.
Kang: Look behind you. (She looks, and Kang uses a ray gun to impregnate her) Insemination complete.
Marge: Really? That seemed awfully quick.
Kang: What are you implying?
The male Agent J from Men in Black is impregnated when he accidentally swallows an embryonic alien, mistaking it for a pill.
In one skit on Robot Chicken, a woman with a Face Hugger attached walks into a pharmacy and asks for a morning-after pill.
Parasitoid wasps are a type of, well wasp, that lay living eggs in side other insects, (mostly caterpillars) that then hatch and consume the host. These wasps often have a relationship with a virus that weakens the caterpillars immune system and alters the cells of the host to be more beneficial to the eggs wasps young.
As Charles Darwin said: "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars."
Botflies and several other insect species lay eggs in large mammals' skin, often near the eyes or anus. The larvae that hatch out don't generally kill their host, but the resulting wounds deplete the animal's strength and can provide an avenue for fatal infections.