Corralled Cosmos

"When the star gates could take them no further they turned against each other, igniting conflicts that would last for centuries."

- EVE Online Intro

So your epic new Space Opera script is coming along, but you're running into some problems. Maybe the vastness of space is laboring your sweet 17th century nautical allusions. Or it begs questions about why your characters bother fighting wars over land and resources when there is a nearly infinite amount of new planets to colonize. The trouble with space being so mind bogglingly huge is that virtually everything we know about civilization wouldn't apply to a world with infinite horizons, and the fans aren't going to appreciate that.

Cue the Corralled Cosmos. Thanks to the magic of plot convenience there is now some impassable obstruction to keep people herded into a relatively manageable area, where they will be sure to explode into a ratings friendly conflict sooner or later. The corral itself can take many forms. It might be a physical barrier like a black hole, asteroid field, or a particle storm. It might be hand waved away to those who ask as "lawless space" where any number of Space Pirates or cosmic horrors might be waiting to ambush you. Hell, maybe there's just a whole lot of nothing. Whatever form it takes, the message is clear: "we don't go there".

Of course, this can be justified if the limitation is to one planetary system - the difference between the timescale and technology necessary for casual interplanetary travel and Casual Interstellar Travel is enormous.

Compare The Wall Around the World and Sci-Fi Writers Have No Sense of Scale.

Anime and Manga

 * In Diebuster, humanity has been confined to a limited area in the Solar System because of the presence of the 'Jupiter Express', a massive swarm of Space Monsters located between Jupiter and Saturn. This phenomenon establishes this series as an Alternate Continuity to Gunbuster, as it implies that on this timeline the Space Monsters weren't defeated by the efforts of the heroes from the original series. Except that isn't true, as the 'Jupiter Express' turns to be an automatized planetary defense system that has been mistaking the Buster Machine pilots for the enemy, NOT the real Space Monsters everyone thought at first.
 * In Legend of the Galactic Heroes, the space between the Galactic Empire and the Free Planets Alliance is a nearly unnavigable gulf that destroys any ship trying to traverse it except for two small (relatively speaking) corridors: one holding the Phezzan system, and the other the Imperial fortress Iserlohn. The possibility of going around the gulf is mentioned, but never attempted.

Film

 * Star Wars—The expanded universe's "hyperspace storms".
 * Also, punching in random coordinates into the hyperdrive and hoping is extremely dangerous, as you might hit a celestial body's mass shadow in hyperspace and explode. Or come out in the middle of a star.

Literature

 * The Dark Side of the Sun-- Terry Pratchett. There's nothing physically restricting people from going further than 53 light-years from Wolf 359 with their matrix engines, but there's no point, as all fifty-odd known races are contained within this area, the 'life-bubble', thanks to Precursors.
 * Justified in the Vorkosigan Saga because interstellar travel is through naturally occurring wormholes. Most wormholes don't lead anywhere useful, and planets with breathable atmospheres are therefore rare and highly prized.

Live-Action TV

 * Played with in Farscape where the vast bulk of space is unknown to the two Great Powers (the Peacekeepers and Scarrans) and called "The Uncharted Territories" where their knowledge ends and filled with unknown terrors. However this is where the bulk of the Moya crew's adventures take place since they are a bunch of escaped convicts (and Crichton).
 * Appeared in at least one episode of Andromeda. People honestly have no clue what might be lurking right next door (in interstellar terms) to their own planet despite an empire that spans three galaxies because their FTL method doesn't involve traveling through that space.
 * Star Trek—The great barriers around the Galactic core and the outside of the galaxy mean leaving the Milky Way isn't really possible. Not to mention that even at Warp speeds, it would take forever to get there.
 * Not that that stopped them from getting there in the first episode. In both of the first two series, even...
 * In the first episode of Next Gen, Q literally corrals the Enterprise with a giant energy net in space, having decided humans are just too barbaric to be allowed out into the universe at large any longer, and demands that we corral ourselves back in our home system. Picard argues that we are capable of learning from our mistakes and growing into something more; the series is book-ended with Q giving him a chance to prove it.
 * Babylon 5—The nature of hyperspace travel in the B5-Verse limits the large-scale area. Hyperspace travel requires beacons and jumpgates or uber-powerful ships to travel anywhere. Thus unknown space remains unknown for long periods and some areas are permanently cut off from hyperspace travel. So you have well-known areas of space where any trip is swift and unknown space where every trip is an expedition lasting years.
 * Only very large capital ships can create their own hyperspace jump points. Earth has Cortez-class explorer ships half the size of the 5-mile long station itself that actually build new jumpgates for ships as small as fighters to use.
 * Firefly—The 'verse lacks any sort of Faster Than Light travel and is a massively complex planetary system. The government also puts out the story that the Reavers are folks who went a little funny spending too much time on the edge of space. For those that don't believe this, the Reavers themselves constitute a perfectly good excuse not to go there and find out. These last two reasons do not survive the end of the movie.

Tabletop Games

 * Used in the old RPG Traveller Twenty Three Hundred. Like the Mass Effect FTL, you had to stop after a certain duty cycle in some kind of gravity well (near a star or brown dwarf) in order to safely reset the engine, giving the fastest ships a maximum travel distance of 7.7 light years. The game used the (at the time) accurate star list and locations around Earth, which meant that to reach a star, say, 8.5 light years away, you might have to head off in a completely different direction to work your way around. It also meant that some exploration paths simply ended because there were no more known stars within range, that some stars were only approachable by one route while others were hubs, and that you might have colonies dozens of light years away, but a star system much closer was beyond reach because it was further than 7.7ly away from another.
 * Warhammer 40,000—Mostly averted:
 * The universe is a massive, sprawling place where isolated worlds can be out of contact for decades or even centuries and the "central government" consists of hundreds of different organizational power bases, most of whom hate each other.
 * There is also the edge of the galaxy, from beyond which Tyranids came, and maybe even something worse than them.
 * Additionally, due to the Astronomican - the psychic beacon on which the Imperium's standard methods of Warp navigation rest - being based in the Solar System, which is around 25000-28000 light years to the "west" from the galactic core, part of the galaxy's "eastward" edge (known in-universe as the Eastern Fringe) is outside the Astronomican's reach, making it extremely difficult and dangerous to explore.
 * And speaking of which, unless you are the Necrons, Warp travel is the only way for Faster-Than-Light Travel, and the Warp is basically WH40K's Hell and afterlife. Every time a ship makes a Warp jump, it stands a good chance of suffering a horrid fate that, at best case, "merely" involves the ship's complete destruction by supernatural "tidal forces". The unlucky ones end up becoming the Warp's resident Eldritch Abominations' playthings. Of course, there is a way around this particular hazard: The Eldar Webway, a vast network of "tunnels" extending through the Warp, whose methods of construction have been unfortunately lost to the passage of time and the resulting chaos from the Fall of the Eldar. It offers a much safer FTL mode of travel (assuming you have access to an intact Webway gate, and managed to activate it), with the only dangers being that the only complete map of the Webway's labyrinthine network is kept in a place inside the Webway, a "few" passages have either become dead-ends or were invaded by Daemonic forces, and - if you are not an Eldar - the Eldar's Fantastic Racism against any and all non-Eldar races.
 * And even though the galaxy's non-Eldar warp-faring races are lucky enough that the above hazards of normal Warp travel don't happen frequently enough to preclude the feasibility of interstellar empires, they still have a few other problems to deal with:
 * 1) Warp travel time is neither instantaneous, nor is it absolutely predictable. Assuming optimal conditions in the Warp (meaning no sudden changes of "Warp currents" or a massive Eldritch Abomination suddenly manifesting to block your path), a trip across the full extent of an Imperial Sector (around 200 light years across) can take around 30–60 days minimum, while a trek from one side of the galaxy to the other can take years to complete.
 * 2) Travelling through "Warp Storms" - the Warp's equivalent of atmospheric storms, the smallest of which are big enough to encompass an entire star system - is practically impossible, and there are vast regions of space that are completely cut off by them from the rest of the galaxy.
 * 3) Many other regions of space, while technically free from Warp Storm activity or any detectable Daemonic presence, mysteriously keep swallowing up every expedition fleet that tries to explore them. Nobody knows why that happens, too, save for the very real possibility that they are inhabited by non-Daemonic Eldritch Abominations, and thus it would be for the best to avoid said areas of space like the plague.
 * 4) A far more mundane threat: Alien pirate fleets roaming the "Wilderness Space" beyond Imperial Sectors. Ork fleets of such a sort are especially common to the point of aggravating frustration for the Imperium.
 * In Fading Suns it is achieved by the fact that interstellar travel requires the codes to local Portal Network, and even finding lost ones is difficult enough, let alone researching them anew. And then, those on the other side may have plans of their own.

Video Games

 * EVE Online—While star gates make the massive eve universe traversable, there are limits to where they can be built and how far they can travel, which accounts borders and giant holes in the eve universe.
 * Averted in Halo. The reason why the Cole protocol (jumping random coordinates before making the jump to Earth) is adopted is to keep Earth's location hidden from the Covenant. Starships could jump directly to Earth if they wanted, but this would essentially let the cat out of the bag.
 * Mass Effect has limitations inherent to mass effect-based FTL drives. Spacecraft travelling on non-relay based FTL build up a static charge in their engines that must be discharged in a planetary atmosphere or it will eventually overload and fry the crew. This limits how far one can travel without finding planets for stopovers to expend the static discharge. If there are no planets between one's starting point and destination, then one can't get there without using a mass relay, and if the territory is unexplored, it would be foolish to go haring off into it without knowing if there's a planet to discharge one's engines at along the way. Further, even if a mass relay is discovered, longstanding galactic protocol dictates that the relay be left alone until its matching terminus can be discovered elsewhere, lest whatever is on the other side be hostile. Whenever a new system is charted by probes, or a new relay is activated, it tends to trigger a swarm of activity as various interests compete for settlement and resource exploitation rights. The resources across the galaxy may be vast, but only a finite amount of them become available at a time.
 * In Battlestar Galactica Online, the mysterious nature of the playable sector, far from known space, leaves both sides trying to figure out what's really going on and has turned their attention from escape.

Web Comics

 * Schlock Mercenary—With the Teraport, it should be possible to travel to other galaxies instantly. Due to the setting's Magic A Is Magic A, it is, just prohibitively expensive power-wise. The exception is the Zoojack wormgate, which leads to the Andromeda galaxy, but it's implied that the wormgate was sent from Andromeda to the Milky Way through slower-than light travel over millions of years in order to connect them, the same way wormgates had to travel by STL to establish new routes before the teraport was reinvented.