So why are these cities so overwhelmingly large? And where do they come from? Here's a list, by region:

North America:

The city of North Am (in Magnus Robot Fighter) does just what it sounds like — it covers almost the entirety of North America, giving you lots and lots of space in which to (what else?) fight robots.

The Maze is a huge network of underground parking garages that stretches all the way from New York to Los Angeles, in the movie Circuitry Man.

Lots and lots of SF stories predict a huge swathe of city stretching along the East Coast of the United States. One of the most famous is Judge Dredd's Mega-City One, which eventually stretches all the way down to Florida.

In Neuromancer and other books by William Gibson, a mega-city stretching from Boston to Atlanta is known as the Boston-Atlanta Metropolitan Axis (BAMA) or The Sprawl.

In He, She And It by Marge Piercy, the urban megalopolis that stretches from the former Boston to the former Atlanta is called The Glop.

And similarly, in the novel The Rise Of The Conglomerates by Thomas Nevins, a huge sprawling "Conglomerate City" occupies most of the East Coast of the United States.

There's also BosWash, the city that stretches from Manchester, NH to Virginia Beach, Virginia. It was first predicted in the 1961 book Megalopolis: The Urbanized Northeastern Seaboard of the United States by Jean Gottman.

The City in Transmetropolitan is commonly believed to be a megacity including New York and stretching as far West as the Great Lakes, which are referred to as its Western lakes.

The Greater Chicago Industrial Zone: In Halo, the former city of Chicago now covers the former states of Illinois, Wisconsin, Indiana. And Chicago is no longer really part of the United States — the people in this city-state consider thesmelves citizens of the United Nations.

In real life, some urban planners talk about an area called ChiPitts, which comprises Chicago and Pittsburgh, and everything in between.

Texarkana in A Canticle For Leibowitz, appears to cover a huge chunk of the former Texas and Arkansas, and becomes the capitol of an empire that rules the Western Hemisphere — and eventually wipes out its main rival, New Rome. (Map from Wikipedia page.)

Texas City, in the Judge Dredd comic, covers a huge area of the former Southwest — including Texas, of course.

Bay City is a massive conurbation covering San Francisco as well as its outlying areas, in Richard K. Morgan's Altered Carbon.

San Angeles appears in many different works of fiction, and it usually encompasses Los Angeles, San Diego and sometimes Santa Barbara. It's the setting for Demolition Man.

Mega-City Two also accounts for five thousand miles of California coastline — or it did, until it was nuked — in the Judge Dredd comic.

South America:

Sao Paulo/Rio: In Ben Bova's Mars, the rural poor stream into the cities of Sao Paolo and Rio De Janeiro in such huge numbers, the two cities grow into "a single urban megacity more than three hundred kilometers wide, that stretched from the beaches to the inland hills, sparkling high-rise towers for the rich, sprawling filthy slums for the poor, and smoggy lung-corroding pollution for all."

Ciudad Baranquilla, aka Banana City, is the mega city that covers most of Central America in the Judge Dredd comics.

Europe:

Greater London — in Sunstorm by Arthur C. Clarke and Stephen Baxter, London has grown outwards massively, swallowing up tons of villages and formerly independent towns. Clarke and Baxter describe London as spreading out, "kilometer upon kilometer of houses and factories... the scattered, helpless city that lay helpless below" a passing airplane.

Edinburgh/Glasgow — it's not strictly speaking science fiction, but there's a lot of talk about these two Scottish cities combining into one megalopolis in the coming century. The two cities could soon be linked by a high-speed maglev train. But it doesn't appear that any science fiction authors have written about EdinGow yet.

Metropia, in the animated film of the same name, is a massive network of subway systems and "undergrounds" linking all the cities in continental Europe. The world is running out of oil, so the leaders come up with the plan to link all of the subway systems into one huge network — which appears to be haunted.

City Europe, in the Chung Kuo series by David Wingrove, covers an enormous area of continental Europe, from Scandinavia to the Mediterranean. The city is made up of a series of "stacks" with the richest people living on the top levels and the poorest down in the wastelands below.

The south of England is occupied by Brit-Cit in Judge Dredd. Plus East Meg One is another mega-city in the Judge Dredd universe, which covers a big chunk of the former Soviet Union, including Moscow.

And of course, there's East-Meg One, the Soviet mega-city in Judge Dredd, which sprawls around the remains of Moscow — until it gets destroyed in a war with Mega-City One.

Africa:

Pan-Africa is a continent-wide quasi-state comprising several mega-cities in the Judge Dredd universe: they include Umar (the former Libya), Simba City (Cameroon), Luxor (Egypt), New Jerusalem (the northeast of Ethiopia), and Casablanca.

Gauteng is another one that doesn't appear to have popped up in science fiction very much, but it's talked about a lot in real life. In a nutshell, Johannesburg (a city already growing way past its capacity) joins up with Pretoria/Tshwane and a number of other municipalities, to form a single megacity. There are already plans to join them via a high-speed "Gautrain."

Asia:

Mega-Tokyo in Bubblegum Crisis. An earthquake splits Tokyo in two, and as the city rebuilds, it gets even larger and much more sprawling, coming to be known as Mega Tokyo. Here's a map of Mega Tokyo, from B-Club Special (via Igarashi) Likewise, Akira takes place in Neo Tokyo, a sprawling metropolis of steel and neon. And the anime Cyber-City Oedo 808 takes place in a fictional future "Edo," or Tokyo, which is apparently much larger than the existing city.

And real-life urban planners talk about the Taiheiyo Belt, which will cover the Pacific coast of Japan including Tokyo, Osaka and Nagoya.

A single continuous robotic structure known as The Host covers almost all the islands of Japan, and 50 million people live inside it, in Magnus Robot Fighter and Rai.

And of course, Judge Dredd does not leave Asia untouched — Hondo City covers most of Japan, from Hokkaido all the way down to Wakayama.

Australia:

Greater Sydney is predicted to encompass a region spanning from Melbourne, all the way up to Queensland along the coast. But as with Edinburgh/Glasgow and Gauteng, it doesn't appear that anybody's written science fiction about this megalopolis yet.

The South Pole:

A continent-wide city called Antarcto covers the whole of the Antarctic, in Magnus, Robot Fighter. Because robot-fighting is best served... cold.

And of course, the city of Holy Terra, or just Terra, occupies almost the entire planet's surface in Warhammer 40,000.

Additional reporting by Alexis Brown. Map layout by Stephanie Fox.

Bova tells about how he got out of jury duty once, by telling the prosecutor and defense attorney he wrote science fiction for a living. (They couldn't get rid of him fast enough.) And then he insists:

If our political leaders had been reading science fiction, we might have been spared the Cold War, the energy crises, the failures of public education and many of the other problems that now seem intractable because we were not prepared to deal with them when they arose.

We could be living in a world that is powered by solar and nuclear energy, drawing our raw materials from the moon and asteroids, moving much of our industrial base into orbit and allowing our home world to become a clean, green residential area.

But very few of us read enough science fiction to learn how to look into the future and see the possibilities of tomorrow, both the good and the bad. Certainly our political leaders are constantly surprised by each new crisis. They don't look into the future any farther than the next election day.

Science fiction, at its best, is an experimental laboratory where you can test new ideas to see how they might affect people and whole societies. To my mind, it should be required reading for everyone.

[Naples News]

Before we launch into our awesome list, let's just cop to something: We're not doing the Aristotelian definition of tragedy. We're just not. Aristotle is for wusses. We're going more with the basic definition: the person who has everything, and then loses it all, or just gets horribly fucked over. In a poetic or meaningful way. Okay?

Every scifi hero Charlton Heston played, ever.

The Charlton Heston science fiction oeuvre is splendid in its variety. But there are a few things you can count on in pretty much all of them. Heston will know better than everybody else around him. He'll be the last bastion of civilization, surrounded by dirty hippies or grandiloquent mutants in whiteface or apes or whatever. And in the end, he'll die because nobody ever listens to him when he's telling them how stupid they are. Why? Why won't they listen? Soylent green is people, you damn dirty whiteface cultists! (Okay, so he doesn't die in Planet Of The Apes, but then he does in the sequel.)

Sam Lowry

In Brazil, the fatal flaw that destroys Sam Lowry is his secret desire to escape the repressive system he's a cog in. (Yeah, okay, we're getting Aristotelean for a sec.) He dreams and fantasizes about being a flying hero in shining armor who fights monsters and soars away, but when he finally gets a chance to escape with the woman (literally) of his dreams, it all goes bad. And he winds up being tortured to death by his former best friend.

Dr. Frankenstein

He's obsessed with the idea of bringing inanimate matter to life, to the point where he drops out of school and spends years digging up corpses and sticking them together. But once he's created his monsterpiece (sorry), he rejects it and drives it away. His cruelty to his creation leads to the deaths of several of his friends, so Frankenstein vows to hunt it down. But Frankenstein doesn't even manage to die at the hands of his creation — instead, in the original novel, pneumonia claims his life after he pursues it to the Arctic. He doesn't even manage to die properly!

Henry Jekyll

Another guy who messes with science and gets messed with in return. Jekyll wants to separate his good side from his dark side, so he drinks a potion which turns him into the embodiment of his bad side, Edward Hyde. At first, it's all fun and games, until Hyde starts going buck wild and Jekyll is turning into him at night, even without the potion. But when Jekyll tries to repress Hyde, the monstrous side of him only comes back worse than ever, killing an old man. Finally, he becomes Hyde permanently, and decides to kill himself instead of paying for his crimes.

Winston Smith

He's another cog in the machine, helping to rewrite history in a future totalitarian state where everybody is watched. Because of his doubts about the machine, he gets lured into joining a resistance group — which turns out to be a set-up. He winds up tortured, and gives up his lover and accomplice. In the end, he doesn't die, but he does get utterly broken by the Party.

Jeff Brundle in The Fly

Annnd another hero who suffers due to his curiosity. Brundle invents the perfect teleportation machine, but a fly gets stuck in there with him. He and his little travel buddy get merged genetically, and they wind up as a half-human, half fly monster. So he decides the answer is to merge his body with his pregnant girlfriend, to add more human DNA to the mix. Sadly, the selfish girlfriend escapes and he ends up being merged with a machine instead, becoming a mangled heap.

Chet Kinsman in Ben Bova's Kinsman series.

It's the far-off year of 1999, and the Americans and Russians are sharing a base deep under the surface of the moon. Chet Kinsman is the chief of the American side, and he's got a plan to avert the war back on Earth. And it almost works, except that his best friend, Frank Colt, betrays him and he winds up dying as a result.

Mad Max

Poor old Max — he just wants to pursue justice as a police officer, but his uprightness gets him in the sights of an evil biker gang. And after they torch his best friend Goose, he becomes embittered and quits being a cop. Only to find that there's no safety in being a civilian, in the crumbling post-apocalyptic Australia. The thugs take out his family, leaving him a bitter loner who has no choice but to kill punks of all sizes, occasionally chaining them to their soon-to-explode bikes and giving them saws. He doesn't die, but he does end up getting smacked around by Tina Turner with really bad hair, and then suffers the indignity of getting rescued by a bunch of kids.

Londo Mollari

Lometa at Everything2 has a very passionate argument about why Londo Mollari is the ultimate tragic hero of Babylon 5:

Londo as a tragic hero went through more twists than a bag of pretzels. Born into a noble family Mollari had a good heart, but he was condemned at every turn by his own bad choices. His ascension to the throne as Emperor was bittersweet and in the end he surrendered himself to his greatest fear, death at the hands of a Narn.

Wolverine

We were arguing earlier about whether Wolverine is a tragic hero. He does lose his family and his memory, and then his girlfriend gets killed. He struggles with his berzerker nature and his bestial killing instinct, and people are always trying to make him wear a yellow leotard. Plus, if you believe Wolverine: The End, he's destined to end up a bitter, lonely old man in Canada, before dying in a fight with his evil mutant brother, whom he thought dead.

Hal Jordan

It's all been undone now, but the greatest Green Lantern had a tragic hero arc in the 1990s. Hal Jordan just couldn't stand to fail, so after the evil Mongul destroyed his home town, Hal went nuts and used his power ring to recreate the wrecked Coast City. Then he went berzerk and attacked the Green Lantern Corps and the Guardians. Finally, he renounced his prized Green Lantern-hood and became the villain Parallax. (Later, this was all revealed to be some form of alien possession, but that's a retcon.) Finally, he died, sacrificing himself to save the sun from being eaten.

Dr. Edward Morbius from Forbidden Planet

His curiosity is his downfall — he's determined to study the artifacts of the long-dead Krell race, so he uses the Krells' "Plastic Educator," not realizing that it shapes items from your mind into reality. The Krell wiped themselves out by unleashing monsters from their own ids, and Morbius wipes out his own expedition the same way, except for his daughter. His id-monster is born of his fatal desire to stay and explore the Krell remains, even after the rest of his expedition votes to go home. Finally, he learns the truth and lets the monster kill him, sparing his daughter's life.

Rick Deckard

He's a retired Blade Runner who has to come out of retirement to take up, once again, a job which he no longer really believes in, killing the artificial Replicants. (And if you believe director Ridley Scott, Deckard himself is one of the Replicants he's killing.) In the end, he's with Rachael, another Replicant, but their time together is going to be short and probably not all that pleasant.

Harvey Dent:

Spoilers for the Dark Knight ahead... So stop reading now if you really haven't seen it yet. (Really?) Harvey is another guy there's some debate over. But it's true that in The Dark Knight, he's pretty much one of the good guys, and his insistence on seeing the world in black and white is part of what helps the Joker break him. Even more than losing his fiancee and half his face, it's the realization that the Joker's right and everything is just random chaos that drives him over the edge and leads to his horrible (maybe) demise.

Additional reporting by Lauren Davis.