A city whose population is larger than a reasonably sized country. The actual size can depend on the average city size of the setting, but for modern or sci-fi settings, you can assume that the number of citizens goes into the hundreds of millions or even billions.

Depending on the setting you can expect to see a lot of tall buildings, endless suburbs and futuristic ways to get around. If you are lucky the author may have even thought of the troubles with providing food and water for all the inhabitants as well as the problems for the environment so many people naturally generate. If you are unlucky however, the heroes may find themselves alone at times and places where that should be impossible given the population density.

Notice that despite the introduction a given city does not count as a Mega City just because it is bigger than a given country. For example, in real life not less than 41 countries around the world have less than a million inhabitants, 17 even less than 100,000, and cities of that size in other countries are normal and therefore would not be seen as mega cities.

The Mega City will probably be the capital or HubCity, and if it's not a MerchantCity, there'll definitely be a BazaarOfTheBizarre if you know where to look. If its land area is restricted, expect it to be a SkyscraperCity.

Occasionally, a Mega City will grow so large that it will become a CityPlanet.
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!!Examples:

[[foldercontrol]]

[[folder: Comic Books ]]

* The City in ''{{Transmetropolitan}}''.
* The world of ComicBook/JudgeDredd is divided into these kind of cities.
** Dredd's home city of Mega City One grew from [=BosWash=] (See Real Life examples below) until it covered the entire eastern seaboard. In fact, the whole point of the ''Apocalypse War'' arc was to trim its sheer size down, as it had become too big.
* Downlode in ''ComicBook/SinisterDexter'' stretches from northern Spain to west Poland.
* ''ComicBook/TheMightyThor'' #372, part of a storyline involving TimeTravel, says that in the future the entire east coast of the USA will be covered by the [=megacity=] of Brooklynopolis (which will be policed by the [[AlternateCompanyEquivalent oddly-familiar]] [[ComicBook/JudgeDredd Justice Peace]]).
* The city of [=NorthAm=] in ''MagnusRobotFighter,'' which covers all of North America.

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[[folder: Film ]]

* The pre-war human cities in ''Film/TheMatrix'', which "spanned hundreds of miles" and needed armies of robots to maintain themselves.
* The BigApplesauce has become this in the 1930's films ''Film/{{Metropolis}}'' and ''JustImagine'' -- in those days New York was pretty much the only skyscraper city in existence.
* ''Film/{{Avatar}}'': In the extended version, and in [[AllThereInTheManual supplementary materials]] the cities of Earth have become this.
* ''Film/{{Star Wars}}'' has the city planet of Coruscant. It's rumoured that one can walk all the way around the planet without ever setting foot on its surface.

[[/folder]]

[[folder: Literature ]]

* In Creator/IsaacAsimov's ''Literature/TheCavesOfSteel'', all of Earth's population lives in eight hundred arcologies known as 'Cities'. The average population of each City is eleven point two million. The governments of three large cities (New York, Philadelphia and Washington) are considering merging into one single ''Mega'' Mega City, but the logistics of maintaining and governing such a large conglomerate have so far prevented any action on the plan.
** Later in the ''Robots/Empire/Foundation'' series, Trantor, and presumably a few other worlds, are globe-spanning versions of these with populations in the billions. Trantor is very much the model for Coruscant.
* Literature/{{Discworld}}: While Ankh-Morpork only has a million inhabitants, it is still the biggest city in the [[MedievalStasis setting]]. In ''Discworld/TheFifthElephant'', Carrot points out that it's actually the largest dwarf city, having more dwarfs than any purely dwarf city. (This isn't as far-fetched as it may seem -- a RealLife example is the city of São Paulo, whose Italian community is larger than any city in ''Italy itself''.)
* In the ''MythAdventures'' series the dimension of Deeva is entirely taken up by an open-air market.
* ''Literature/TheThirteenAndAHalfLivesOfCaptainBluebear'': The Capital of the continent of Zamonia, Atlantis, has over 200 million inhabitants.
* The arcologies in ''Literature/TheNightsDawnTrilogy''.
* In VladimirVasilyev's ''BigKievTechnician'' UrbanFantasy series, Big Kiev in this AlternateUniverse is roughly 600 miles in diameter. Big London is also mentioned, although it may be smaller. It takes 9 hours on a train to get from the Black Sea in the southern part of town to the Center (where our Kiev, Ukraine, is located). One of the old cities absorbed into Big Kiev is L'viv. Only canned goods are available in the Center due to lack of farmland or cattle so far from the edge, unless you're willing to spend a fortune on fresh meat and fruit.
** Big Moscow is mentioned to be even larger, although younger.
*** A military conflict is mentioned to have happened in the past between Big Moscow and Big Berlin. DoesThisRemindYouOfAnything
** This can be partially explained by cities apparently growing ''on their own'', as a jungle would. This fits into the overall theme of all machines in this world being alive.
*** Apparently, the major cities have been slowly growing for the past 300,000 years in the novel's timeline.
* WilliamGibson's SprawlTrilogy has the titular [[TitleDrop Sprawl]], more officially known as BAMA, the Boston-Atlanta Metropolitan Axis, presumably an extension of the real Bos-Wash. Also notable for being almost completely covered by geodesic domes. Judging from descriptions in {{Neuromancer}} Chiba City and the other cities around Tokyo Bay also count.
* In one of AndreiLivadny's ''TheHistoryOfTheGalaxy'' novels, Earth cities are mentioned to have become these with populations of major cities approaching 20 billion ''each''. That's nearly triple the population of the entire world today in a single city. This is the main reason why President John Winston Hammer of the [[TheEmpire Earth Alliance]] sends a fleet to force the recently-discovered [[LostColony Lost Colonies]] into submission, so as to offload the extra population. By the time of the later novels, most of the population has moved to new colonies or died in the First Galactic War (the 30-year war with the colonies, which Earth ultimately loses) with only about 100 million people left on Earth. Most urban areas, now abandoned, are covered by lush jungles, and many surviving landmarks have been moved to other areas for preservation. After the war, the colonies emerge as the industrial, economic, and scientific power in human space, forming the [[TheFederation Confederacy of Suns]] for mutual protection (Earth isn't included).
* In F. Paul Wilson's ''LaNague Federation'' series, Earth (and some colonized planets) has several Megalops with stupidly huge buildings and nightmarish overpopulation. Food-riots are not pleasant affairs.
* Nessus from ''Literature/BookOfTheNewSun'' by Creator/GeneWolfe appears to be one of these in decline (along with rest of the planet.) It takes days to travel from its center to the outskirts. Large portions of it, however, are in ruins and inhabited by cannibals.

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[[folder: Pinball ]]

* Appropriately enough, the ''Pinball/JudgeDredd'' pinball takes place in Mega-City One.

[[/folder]]

[[folder: Tabletop Games ]]

* ''TabletopGame/{{Warhammer 40000}}'' has Hive Cities, mountains of metal housing millions of inhabitants and dependent on imported food and water from neighboring [[SingleBiomePlanet Farm Planets]]. They tend to settle into very stratified societies, with the administrators and wealthiest citizens living comfortably in the Spire, while gangs, mutants, and worse struggle to survive in the dark and decaying Underhive. Many of the setting's "{{City Planet}}s" aren't actually covered entirely by urbanization, but are rather dotted with hive cities separated by the resulting {{Polluted Wasteland}}s.
** Holy Terra is a proper CityPlanet, though individual complexes stand out as pseudo Mega Cities in their own right: the Imperial Palace covers a good portion of the northern hemisphere, the Inquisition's headquarters is beneath what used to be the southern ice cap, and the Hall of the Astronomicon [[RefugeInAudacity was carved out of the interior of Mount Everest]]. Unlike many settings' hive cities, the value of Terra is not as a trade hub, but as the slow-beating administrative heart of the Imperium and the holiest of religious sites.
* Sprawls/metroplexes in ''TabletopGame/{{Shadowrun}}''.
** Like much of the Shadowrun universe, these are most likely inspired by William Gibson's work, outlined above.
* Mort City in ''SLAIndustries''. [[UpToEleven which, we feel we should stress, is roughly the size of Eurasia.]]
* Though there have been many cities mentioned in ''TabletopGame/MagicTheGathering'', none quite so massive as the plane-spanning city of guilds, Ravnica. A city so big, it has all five mana-producing lands contained within it with room to spare. A city so big, it took ''[[http://wiki.mtgsalvation.com/article/Category:Ravnica_block two]] [[http://wiki.mtgsalvation.com/article/Category:Return_to_Ravnica_block blocks]]'' (at three card sets per block) to cover it all.

[[/folder]]

[[folder: Video Games ]]

* Mega-Primus in ''{{X-Com}}: Apocalypse''.
* One of the playable locations in ''VideoGame/MassEffect3'' is a city representing the unification of Vancouver and Seattle.
* Kaineng City from ''GuildWars Factions''.
* One of the ultimate goals in any ''VideoGame/SimCity'' game is to reach as high a population as possible. In the original game, reaching a population of 100,000 would upgrade your city into a Metropolis. Reaching 500,000 citizens meant that your city be classified as a Megalopolis.
* Mute City in ''VideoGame/{{F-Zero}}''. Formerly called New York City (according to the anime), it grew to a population of over two billion people and aliens.
* One of the locations in ''VideoGame/DreamfallChapters'' is Europolis, a dystopian Stark city covering most of Central and Western Europe.
* ''VideoGame/TheMatrixPathOfNeo'' has the pre-war human Mega-cities during cutscenes.

[[/folder]]

[[folder: Webcomics ]]

* ''Webcomic/GunnerkriggCourt'': The court itself has gigantic proportions, its full size has yet to be revealed.
* ''{{Shifters}}'': The comic takes place in Shade City a Mega City that encompasses a vast amount of territory in the Pacific Northwest.

[[/folder]]

[[folder: Western Animation ]]

* ''WesternAnimation/AvatarTheLastAirbender'': The Outer Wall of Ba Sing Se seems to encompass nearly 10% of the land area of the largest continent on its planet, and its population is equally gigantic, especially in comparison to those of the entire Air Nomad and Water Tribe civilizations.
* ''TheJetsons''

[[/folder]]

[[folder: Real Life ]]


* The proper term to describe cities- more specifically, Broad-stroke regions- that have reached extreme levels of population and urban development is ''Megalopolis''. The following examples listed below all qualify, as most of them are a chain of metropolitan areas that are so closely connected to each other that they have begun to overlap.
* According to TheOtherWiki, there are about [[http://en.wikipedia.org/wiki/List_of_urban_areas_by_population as many people in Jakarta]] [[http://en.wikipedia.org/wiki/List_of_countries_by_population as there are people in Australia]] (especially if you count Jakarta's satellite cities and zones).
** There are about as many people in Tokyo as there are people in [[CanadaEh Canada]]. Makes [[TokyoIsTheCenterOfTheUniverse a certain trope]] feels juuuuust a little bit {{Justified|Trope}}.
** If Tokyo were a separate country, it would be the 34th most populous in the world, after UsefulNotes/{{Poland}}.
** Keihanshin (Kyoto-Osaka-Kobe) is no slouch either. The figures varies depending on the method, but it is somewhere around 17-20 million people. Unlike other metropolitan regions, however, Keihanshin was unique in that Kyoto and Osaka were (and to some extent, still are) separate cities with separate civic cultures for most of Japan's history. It was only until rise of modern transport in the early-to-mid 20th Century that the two cities started to form the metropolitan region.
* In the US (and other places), urban sprawl has started expanding cities to the point where they run together. For instance:
** The first was known originally as [=BosWash=] (sometimes [=New BosNYWash=] given New York City is a big percentage of the people), a near contiguous mass of cities and suburbs running from Boston to Washington DC. Currently the cities in this area have yet to fully coalesce, although New York City/North Jersey/Fairfield County (CT) and Philadelphia/Camden (NJ) are close, as are Boston, Worcester (MA), and Providence (RI). [[hottip:*:The fastest growing area in Massachusetts is the corridor of outer suburbs between Route 128 and I-495 known collectively as [=MetroWest=], while Route 1 between Boston and Providence is essentially one long commercial strip anchored by the Automile in Norwood (just off 128) and Gillette Stadium in Foxboro, somewhere in the middle.]] Likewise, the DC area spills over into northern Virginia and Maryland, to the point of sometimes being grouped with Baltimore.
** The Los Angeles metropolitan area is currently the largest (in terms of area) metropolitan area in the United States and the second most populous, with more than 15 million residents.
*** The coastline of Southern California is essentially this. Driving on Interstate 5 from the US-Mexico border at San Diego all the way to the Interstate 210 interchange in north San Fernando is about 140 miles of urban scenery. The total distance is really about 160 miles, but 20 of that goes through a nature preserve in Camp Pendleton.
** The San Francisco Bay Area (in California), depending on where exactly you draw the boundaries, comprises up to 8.5 million people and is potentially the 2nd-largest metropolis in the United States - after the Los Angeles area - with a steadily growing population from immigration into the region. It's a well-networked mesh of cities, suburbs, and large towns that surround the SF Bay, and continue to extend outward from there.
** South Florida (the metropolitan area based around Miami) is a continuous strip of connected cities running 110 miles, though never more than 20 miles wide. It's the longest unbroken strip of urbanization in the United States and is home to over 5 million people.
** The Dallas-Fort Worth Metroplex of Texas has about 6.5 million inhabitants living in well over 200 individual towns and cities, the largest metropolitan area in the Southern United States. It is generally split between two main divisions, the Dallas-Plano-Irving group and the Fort Worth-Arlington group, but they're all close enough that it hardly matters.
* MexicoCity. Depending on who asks, the population ranges between 20 and 22 million people. That's more than the entire population of some Latin American countries like Chile.
* Outside of the western world:
** There are very large cities in China such as Shanghai (20 million) and Beijing (17 million) and there are a number of large cities in the Pearl River Delta such as Shenzhen (12 million) and Guangzhou (16 million) which may one day merge to form the largest mega city in the world [[http://www.telegraph.co.uk/news/worldnews/asia/china/8278315/China-to-create-largest-mega-city-in-the-world-with-42-million-people.html]].
** Mumbai and Delhi/New Delhi in India have populations of over 20 million and over 15 million respectively.
** UsefulNotes/{{Cairo}} (20 million people when you include Giza and the suburbs, which you should) and Lagos (12 million) in Africa.
** Moscow (12 million officially, over 20 million if you count all them transients, unregistered residents and illegal migrants, and another 5 million from the suburbs).
* The fertile valleys of the Nile, Tigris, and Euphrates rivers allowed Babylon, [[AncientEgypt Thebes, and Alexandria]] to each become a MegaCity at different points in history, at least by the standards of their time. Later, grain brought in from all over the Mediterranean (including the aforementioned Nile valley) allowed AncientRome to do so.

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