View source for Single-Purpose Planet

{{trope}}

At present, the human race occupies but a single planet, so it makes sense that we conduct a wide variety of business upon it. What happens, however, when we eventually reach for the stars, and have whole solar systems, if not galaxies to work with? It may then make sense to start specialising, dedicating entire planets to one hyper-specific usage for maximum efficiency.

Enter the '''Single-Purpose Planet''', a celestial body dedicated to just that one thing. Can come about as part of race's attempts to utilise empty planets, or make use of those they have forcibly conquered. Very rarely, they may be custom-built, demonstrating its owners' immense power and wealth.

This trope exists almost solely in science-fiction, representing a possible future of intergalactic development and colonisation. Unless one is willing to call asteroids "worlds", this trope requires cheap and easy [[Faster-Than-Light Travel]] to work at all.

By necessity, a Single Purpose Planet may also be a [[Single-Biome Planet]].

Supertrope to [[City Planet]] and [[One-Product Planet]]. Compare with [[Planet of Hats]], where there's only a single culture or behaviour on the planet.

{{examples}}
== [[Film]] ==
* Coruscant from the ''[[Star Wars]]'' franchise appears, from what we've seen of it, to be a [[City Planet]] that exists solely to govern the rest of the Republic/Empire/etc.

== [[Live-Action TV]] ==
* The Library from the ''[[Doctor Who]]'' episodes ''Silence in the Library'' and ''Forest of the Dead'' is a planet dedicating to archiving every book ever written.
** The episode ''The Poison Sky'' reveals the ''Sontaran'' plot is to repurpose the Earth as a hatchery for their young.
* Upon the death of {{spoiler|Ace Rimmer}} in ''[[Red Dwarf]]'', the crew follow the small vessel carrying their remains, and finds what amounts to a cemetery planet for their millions of incarnations.
* Several worlds identified as "pleasure planets" have appeared across multiple incarnations of ''[[Star Trek]]'' -- these appear to be worlds that specialize in being tourist destinations, providing all manner of entertainment and [[Exactly What It Says on the Tin|pleasure]] to visitors. 
** "Wrigley's Pleasure Planet" was mentioned in the very first episode of ''[[Star Trek: The Original Series]]''
** The planet Risa was first mentioned in an episode of ''[[Star Trek: The Next Generation]]'', and has apparently been in business for centuries -- reference is also made to it in episodes of ''[[Star Trek: Enterprise]]'', ''[[Star Trek: Strange New Worlds]]'', ''[[Star Trek: Picard]]'' and the "New Trek" movie ''[[Star Trek Into Darkness]]''.
** Casperia Prime, the "vacation capital of the Horvian Cluster", was described as being on a par with Risa in two episodes of ''[[Star Trek: Deep Space Nine]]''.
* As a [[Spiritual Successor]]/parody of ''[[Star Trek]]'' it's only natural for ''[[The Orville]]'' to have a "pleasure planet" of its own. "Arboreus Prime" is described as an amusement park planet, complete with rides, and hotels for guests.
** "Rana 3" is a farming colony controlled by The Union.

== [[Radio]] ==
* The planet Magrathea, which first appeared in the original radio version of ''[[The Hitchhiker's Guide to the Galaxy]]'', was essentially a factory for building ''other'' planets to order.  Thanks to dimensional shenanigans it was [[Bigger on the Inside]], and held enough space for multiple earth-sized worlds and the mechanisms needed to construct them.

== [[Tabletop Games]] ==
* ''[[Warhammer 40,000]]'': 
** Agri-Worlds are entire planets dedicated to agriculture.
** Forge Worlds are entire planets converted into factories, usually for armaments and other war materiel.

== [[Video Games]] ==
* Oxide's plot in ''[[Crash Team Racing]]'' is to turn the Earth into a giant parking lot.
* The planet Porrima II in [[Bethesda|Bethesda Game Studios]]' ''[[Starfield]]'' is owned by the Paradiso corporation, which runs it as a resort.  (Which causes a problem when a two-hundred-year-old [[Generation Ships|Generation Ship]] finally arrives there and its crew wants to settle on their intended new home.)

== [[Web Original]] ==
* The [[Shared World|collaborative writing project]] ''[[Fenspace]]'' has several, if you are generous enough to consider an asteroid-sized body a "world".
** [http://www.fenspace.net/index.php5?title=Disney%27s_World Disney's World].  Originally the main belt asteroid 4017 Disneya, the [[Disney]] corporation had it towed from the asteroid belt and then turned into a [https://kardashev.fandom.com/wiki/Cole_Habitat Cole Habitat] with mouse ears.  Inside of the now hollow and spherical former asteroid, Disney has built a space-based version of their Earthbound theme parks.
** "Renfaire", found on asteroid 4860 Gubbio in the Main Belt, is owned by historical-reenactment fen. The park's biggest attraction is its resident population of wandering minstrels, troubadours, and bards. Its second-biggest attraction is the monthly roasting of an entire ox - this is the only red meat some people in the Belt ever eat. 
** "Jurassic Rock" is the nickname of an asteroid owned by the Vesta Institute of Biochemistry. Originally intended as an easily-isolated place to perform dangerous genetic engineering experiments, successes at cloning pseudo-dinosaurs in 2011 created a tourist attraction. People come from across the System to see the (small) herds of Protoceratopses, Kentrosaurs, and Pterodactyls kochi. 
** "Monster Asteroid" is the name given to the hollowed-out interior of 2277 Moreau, which is filled with jungle terrain, complete with a underground sun. This park is devoted to all of the classic giant monster movies. [[Godzilla]], [[Mothra]], [[Rodan]], [[Gamera]], [[King Kong]]... they're all represented. Rumors that some of the monsters are not animatronic, but instead a bio-engineered living creatures, are unfounded.

== [[Western Animation]] ==
* A favourite trope of ''[[Invader Zim]]'', where the Irkens conquer planets and assign them an arbitrary function.
** The first planet we are introduced to is Conventia, the convention hall planet.
** Devastis is a planet where the elite soldiers are tested for their ability to become invaders.
** Hobo 13 serves as a general military boot-camp.
** Blorch is assigned as a "parking structure planet" on a whim on the eve of its conquest.
** Vort is repurposed as a [[Penal Colony|"Military Research Prison"]].
** Judgementia is where Irken trials are conducted.
** An unnamed planet is shown covered in conveyer belts, and used as a distribution hub.
** Foodcourtia [[Exactly What It Says on the Tin|you can probably guess]].
* ''[[Futurama]]'' has Spa 5, a supposed relaxation planet and fitness camp.
** You'd be better off visiting Planet XXX, the nude beach planet.
* ''[[Shadow Raiders]]'' has the five-planet star system of the Cluster, where there are four inhabited planets, which are Fire, Rock, Bone, and Ice, with their unique inhabitants and resources where each depends on each other. There are also other planets from star systems that neighbour it like Tek and Sand:
** Fire is covered in volcanoes and lava pools, with humanoid aliens burning fire on the tops of their heads. They produce energy for the Cluster.
** Rock is made of rock, and the people are humanoid rock people with gem-like hair. The resources they produce are metal ore and minerals.
** Bone is known for having earth and fertile soil, mostly made of swamps. The people on this planet are reptilian, and they produce food as their resource.
** Ice is a frozen planet with the aliens being blue insectoids. The planet's resource is water.
** Planet Tek was a planet eaten by the Beast Plant. It was made of metal and looked composed of technology. Its inhabitants resembled robots.
** The Beast Planet is the show's main antagonist that sends out Beast Drone and Beast Generals (beings made from null-matter), who are sent out to planets to crush their defenses to ensure the Beast Planet's consumption.


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