History Main / PlanetaryParasite

* The Mycon's "Deep Children" from ''Videogame/StarControl2'' are dropped from orbit, burrow their way down to the mantle of a planet, grow tendrils throughout the planet, then start tearing holes in the planet's crust, turning it into a lava world. The whole process takes about a year.

These guys, however, will employ ''a whole planet'' as their host. Just as our parasites feed on our nutrients to grow, these guys will deplete the planet of its natural resources (this is likely to bring bad consequences for the planet's inhabitants), and use them to complete its reproductive cycle, spawning more of its race. Once the cycle has been completed, the newborn will somehow leave the planet to find another one, where they will start a new cycle. Destroying the planet when leaving it is optional.

* In ''KamenRiderGaim,'' the Helheim Forest proves to spread its seeds like wildfire, and there is a very real threat that if the dimensional portals aren't closed, this invasive species could end up turning Earth into a new Helheim. [[spoiler: We know because this is what happened in the formerly-Earthlike world now known as Helheim. Oh, and the monsters used to be that world's people and animals, as anything that eats the fruit of the plants becomes an Inves monster and ends up spreading the seeds further still. Earth has ten years left.]]

* The Big Gete Star from the ''Anime/DragonBallZ'' movie ''The Revenge of Cooler'' probably counts, since it was a mechanical life form that was trying to absorb New Namek.
** The Tree of Might from the movie of the same name is another such example, though it devouring the Earth is only a means to harvest its fruit.

* ''TheBlackSandBar'': The World Eater.

* The Big Gete Star from the ''Anime/DragonBallZ'' movie ''The Revenge of Cooler'' probably counts, since it was a mechanical life form that was trying to absorb New Namek.

* The Dark One Worm from ''WesternAnimation/{{Super Robot Monkey Team Hyper Force Go}}!!''. It's also implied that there are other members of its species on other planets.

* ''Series/DoctorWho'': The 6th Doctor episode "The Twin Dilemma" featured the Gastropods, a race of nearly indestructable creatures who devastated entire planets, but whose eggs couldn't hatch unless seared by a supernova first, limiting their spread.

* ''TabletopGame/CallOfCthulhu'' boxed set ''Spawn of Azathoth''. If a Seed of Azathoth strikes a planet, it can penetrate it and grow into a Spawn of Azathoth the size of a star. All that's left of the planet is shattered ruins. The former fifth planet of the solar system suffered this fate: its remains are the Asteroid Belt.

* Lavos from ''Videogame/ChronoTrigger''. Similar to the previous example, but he doesn't create an alien army, is instead exploited by the planet's mages (doesn't end well), and we get to fight some of the offspring before they're launched to other planets.
* The Old Gods from ''VideoGame/{{Warcraft}}'' are planetary parasites that merge themselves to a planet and slowly corrupt it. Whether this would eventually destroy the planet is unknown, as the Old Gods on Azeroth were sealed away by the Titans (they could not be killed, having already corrupted the planet to such a degree that removing them would've required the destruction of Azeroth).

* ''Videogame/MasterOfOrion II'' had the space eel, a space monster that would target planets to use as spawning ground. Left to its own devices, eventually you'd end with two space eels.

These guys, however, will employ ''a whole planet'' as their host. Just us our parasites feed on our nutrients to grow, these guys will deplete the planet of its natural resources (this is likely to bring bad consequences for the planet's inhabitants), and use them to complete its reproductive cycle, spawning more of its race. Once the cycle has been completed, the newborn will somehow leave the planet to find another one, where they will start a new cycle. Destroying the planet when leaving it is optional.

* In ''FiftyTwo'', one of the possible futures that Rip Hunter foresees (and successfully averts) involves [[spoiler:Mr. Mind]] spawning 52 giant extradimensional parasites that feed off the mental energies of entire ''universes''.

** In universe, it's arguable that he ''does''. The sequel, ''ChronoCross'', exposits that when Lavos came to the planet, it chose one species (early Man) and evolved it rapidly. Mankind developed an instinctual affinity for Lavos and his specific brand of energy, which is why the aforementioned mages (and much of the rest of human society, for that matter) eventually sought him as a power source. Humans are [[AncientAstronauts the basically the descendants]] of this EldritchAbomination, and therefore are themselves the aliens.

* ''[[Videogame/MetroidPrime Metroid Prime 3]]'' reveals that the origin of Phazon is a possibly-sentient planet known as Phaaze, and that it sends seeds over to other planets in order to infest them with Phazon.

These guys, however, will employ ''a whole planet'' as their host. Just us our parasites feed on our nutrients to grow, these guys will deplete the planet of its natural resources. This is likely to bring bad consequences for the planet's inhabitants.

* ''Videogame/MasterOfOrion II'' had the space eel, a space monster that would target planets to use as spawning ground. Left to its own devices, eventually you'd end with two space eels.

* The Big Gete Star from the ''DragonBallZ'' movie ''The Revenge of Cooler'' probably counts, since it was a mechanical life form that was trying to absorb New Namek.

* ''BlakesSeven'': Zil is one of a humanoid species of parasites who live on the surface of a living planet called "Host."

* ''DoctorWho'': The 6th Doctor episode "The Twin Dilemma" featured the Gastropods, a race of nearly indestructable creatures who devastated entire planets, but whose eggs couldn't hatch unless seared by a supernova first, limiting their spread.

* ''CallOfCthulhu'' boxed set ''Spawn of Azathoth''. If a Seed of Azathoth strikes a planet, it can penetrate it and grow into a Spawn of Azathoth the size of a star. All that's left of the planet is shattered ruins. The former fifth planet of the solar system suffered this fate: its remains are the Asteroid Belt.

* The Parasite from ''{{Evolva}}''. A giant egg comes to the planet, develops lots of tentacles, creates an army of aliens, and uses the planet's resources to make new eggs, supposedly to send them to other planets.
* Lavos from ''ChronoTrigger''. Similar to the previous example, but he doesn't create an alien army, is instead exploited by the planet's mages (doesn't end well), and we get to fight some of the offspring before they're launched to other planets.

* Jenova from ''FinalFantasyVII''.
* ''[[MetroidPrime Metroid Prime 3]]'' reveals that the origin of Phazon is a possibly-sentient planet known as Phaaze, and that it sends seeds over to other planets in order to infest them with Phazon.
* MasterOfOrion II had the space eel, a space monster that would target planets to use as spawning ground. Left to its own devices, eventually you'd end with two space eels.

* The Dark One Worm from ''{{Super Robot Monkey Team Hyper Force Go}}!!''. It's also implied that there are other members of its species on other planets.

* [[MastersOfOrion]] II had the space eel, a space monster that would target planets to use as spawning ground. Left to its own devices, eventually you'd end with two space eels.

Most parasites use a single living being as their host, which they use to grow, develop their bodies, and finally create a offspring of new parasites which will invade another person.
These guys, however, will employ ''a whole planet'' as their host. Just us our parasites feed on our nutrients to grow, these guys will deplete the planet of its natural resources. This is likely to bring bad consequences for the planet inhabitants.

* The Dark One Worm from ''{{Super Robot Monkey Team Hyper Force Go}}!!''. It's also implied there are other members of it's species on other planets.

Most parasites use a single living being as their host, which they use to grow, develop their bodies, anf finally create a offspring of new parasites which will invade another person.

Compare PlanetEater, where the parasite doesn't bother to progressively feed off the planet's resourced and directly ''eats'' it, and PlanetLooters, which are more similar to thieves than to parasites.