Portal Network



""We came through that big round thing.""

- John Sheppard, Stargate Atlantis

Simply put, there are lots of "islands of habitability", and conventional travel between them, if possible at all, is time-consuming, expensive, and generally not attempted unless there is absolutely no other choice. However, there is a set of gates or jump points connecting them together, allowing for near-instantaneous travel.

This results in what can be called a "graph universe": the connected islands/communities/planets are vertices and the portal links are edges, and the rationality of travel between them depends not on the distance, but on the existence of a known link between them.

In science-fiction versions, it is common for portal transits to induce disorientation, hallucinations, or nausea which make starship crews temporarily extra-vulnerable immediately after transit.

Considering that it would take thousands if not millions of years to set up an interstellar Portal Network without any other means of Faster-Than-Light Travel, it is not uncommon for such things to have been made by the Precursors, in which case the gates are usually (though not always) Lost Technology.

As these provide both a relatively realistic form of Casual Interstellar Travel and justifies the concept of Space Is an Ocean enough to permit choke point naval battles, Portal Networks are common throughout all but the hardest varieties of Speculative Fiction, which disallows teleportation altogether. They are a convenient means of providing simplified game mechanics, and so are common in both video and tabletop games. In addition they allow writers to avoid making embarrassing scaling errors, if done right.

Compare Teleporters and Transporters, Cool Gate, and Hyperspace Lanes. For a videogame sort-of-equivalent, see Warp Whistle. A Portal Door may be used as the medium of transport.

Anime & Manga

 * Cannon God Exaxxion - The Riofaldians get around the galaxy by using gigantic space stations powered by antimatter that open and sustain wormholes.
 * Cowboy Bebop has the gate network, a series of gates that allow starships to move through the solar system at speeds approaching significant fractions of light speed. It's possible to get around without using them (which the Bebop crew are forced to on occassion), but it takes a lot longer.
 * In Divergence Eve as a crucial part of the plot backstory.
 * In the Sonic the Hedgehog OAV, Sonic the Hedgehog The Movie, the Land of Darkness (and presumably the Land of the Sky) has "Warp Zones" scattered all over it; these are invisible portals that connect, via an extradimensional "tunnel" presumably intended to serve as a Shout-Out to the Special Zones of the games, two specific points on the planet.
 * In Heroic Age, space navigation is only possible either by using psychic powers like The Precursors did, or the "starways" that The Precursors set up. The Precursors also travelled to another galaxy using a Cool Gate.

Comics

 * Decades before Stargate, the Marvel Universe had its own portal network referred to as Stargates. These were used by the Shi'Ar Empire to travel around the universe. Sometimes they were ground-based gates for people to walk through, other times they were enormous space-based ones for ships to use.
 * Also in the Marvel Universe, a dimension known as The Crossroads is full of portals to various dimensions, as well as a roads that lead to all of them and a central point with a "signpost" (in the form of a tree with branches shaped like pointing arms) on it. The Incredible Hulk was banished there (by Doctor Strange) after he was trapped in his monster form (in a plotline that lasted several issues) so he could find a world were he could be happy. (He failed.)
 * The universe of Empowered has the LotusNodesTM Portal Network granted to the Superhomeys. It has a Mass/distance limitation that would be higher if the team didn't chintz out on their network plan.
 * At one point, Flash rogue Mirror Master had access to a Mirror Dimension which connected the back of every reflective surface in the world.

Fan Works

 * The portgates in the Hunter's world in With Strings Attached.

Literature

 * The Trope Codifier for genre SF was the Alderson Drive used for interstellar travel in Larry Niven and Jerry Pournelle's 1975 novel The Mote in God's Eye (sporadic earlier examples existed, but this was the really influential one). It only works at specific "Alderson Points" in a star system, each of which leads to another specific system. Activating the drive anywhere else just burns up a lot of fuel for nothing. The story is a partial deconstruction: the Moties only escaped discovery because the only point into or out of their system leads within a supergiant star that would destroy unshielded ships on arrival.
 * Of course all these spoilered problems are averted in the sequel (The Gripping Hand/The Moat around Murcheson's Eye) when
 * Iain M. Banks's The Algebraist features a similar idea; the novel's wormholes only link specific systems and must be towed into place if severed - starships themselves are firmly sub-lightspeed.
 * Manifold Space by Stephen Baxter. The portals employ quantum entanglement teleportation, so transportation (being destroyed at the source and reconstructed at the destination) is limited to lightspeed and portals have a limited (though huge) number of uses.
 * The various systems in Lois McMaster Bujold's Vorkosigan Saga are connected by wormholes. Some planets (such as Beta Colony) were originally settled by sublight starships before the network came online, but there's no indication anyone even knows how to find others (such as protagonists' homeworld Barrayar.) There is some significant travel time between individual wormholes, which takes up all of the multi-month travel time between distant worlds, but it's all within single star systems; nobody makes interstellar journeys the old-fashioned way anymore.
 * Diana Wynne Jones loves this trope. It appeares both in the Chrestomanci series and in Howl's Moving Castle.
 * The portal stones in Robin Hobb's "Farseer Trilogy" and its sequels.
 * The Morgaine Cycle by C. J. Cherryh has this. The gates link together planets and locations on each planet. They are associated with an advanced but amoral race called the Qhal, but all the evidence points to the Qhal having found and copied gates built by a vanished older race, who in turn weren't the original builders. As to why those ancient races vanished - well, let's just say that's why Morgaine's job is to try to destroy the gate network before the same thing happens again.
 * Diane Duane's Young Wizards series has the Invisible (And Intangible) To Normals worldgates. On Earth these can only be used by wizards, but on worlds with both much more advanced technology and no Masquerade they can be used by anybody.
 * In the trilogy starting with Foundation's Fear, the Empire uses a vast network of wormholes to provide instantaneous travel across the galaxy.
 * The Redemption of Althalus by David Eddings has two such gates that, when used by the right person, can serve as such a link to anywhere (or nowhere, or ).
 * The Wood Between the Worlds, from CS Lewis' The Magician's Nephew, is an interesting variant. Rather than each world being connected directly to another (though these connections, too, exist), each world is connected to a single pool of water in the Wood Between the Worlds, and you can get to any world via the Wood...provided you can figure out which pool goes where, since they have no more distinguishing features than any other pool in any other forest.
 * Into the Looking Glass, by John Ringo, has the titular Looking Glasses (so named because they resemble a mirror) caused by the Florida Anomaly function as portals. The portals technology ends up being exploited and expanded when it's figured out how to make them work. Airplane travel is all but over in the first few years of them functioning with Airports and train stations being an easy place to place a portal network.
 * Carl Sagan's Contact, the novel and movie adaptation.
 * Bob Shaw's Night Walk has the Null-Space, which is somewhat random. Space is kind of divided in areas of around 1 light-second diameter; if you made a Nullspace jump anywhere in area A, you go to area B, but jumping in area B doesn't get you back to area A, but to area C. And jumping in the area just north to A (say, A+1) you don't go to B+1, but to J. And it can't be predicted. Humanity managed to create some kind of Portal Network by sending lots of hyperspace drones that jumped again and again, until some of them finally got by blind luck back to known space, thus recording a route. Later the main character
 * In Dan Simmons's Hyperion novels, most interstellar travel is by way of farcasters, artificial wormholes, since even super-luminal travel can be very slow over interstellar distances. After an expensive and time-consuming sublight construction project around a new planet a completed Singularity Sphere connects the planet to the rest of the WorldWeb, and literally millions of individual Farcaster gates can be built on the planet below, connecting to every other planet in the Hegemony of Man. While spaceships travel using large orbiting Farcaster portals most personal travel is done without every leaving a planets surface.

Farcaster portals eventually became so commonplace that houses were built that have their individual rooms on entirely different planets; with each doorway being a portal. All hell breaks loose when  It gets better.
 * John E. Stith's Reunion on Neverend involves the discovery of a portal network as a subplot.
 * David Weber's Honor Harrington novels slightly subvert this trope by having Casual Interstellar Travel of the vanilla variety (by hyperspace) for everyone, but featuring a wormhole network that allows for instantaneous travel between its termini, thus radically cutting on a delivery times. Naturally, the heroes' homeworld has the biggest bunch of those holes. Wormholes in the Honorverse don't really form a network, though. Various wormhole termini are usually too far apart for anyone to get from one to another, without hyperdrives that also allow FTL travel. They just supply a few very convenient shortcuts between some places.
 * The Antares novels have a naturally-occurring variant, known as foldpoints.
 * The Pendragon Adventure books.
 * The World of Tiers series by Philip Jose Farmer.
 * Star Gate and The Witch World and probably lots of other books by Andre Norton.
 * Ground level portals built by the lost lost "Roadbuilders" were the main form of transportation in John deChancie's Star Rigger series. Due to the necessity of having to enter the portal at a very high rate of speed, most cargo was transported by gigantic, fusion powered 18-wheelers. The plot turns on the fact that no-one has a complete map of the network, meaning that the known network is ruled by authoritarian governments, and the only way to escape them is to travel through unmapped "potluck" portals, which are so named because no-one has yet returned from them.
 * The Starfire books by David Weber feature warp points in two varieties, open and closed. Open points are detectable and can be stumbled through by accident. Closed points are not detectable; the only way to find and use them is to first travel through them from the other (open) end.
 * Starplex by Robert J. Sawyer features a network of portal points spanning the entire universe. All the points begin dormant, but come online whenever something touches them. Sometimes they're opened by random debris, but most are activated deliberately by advanced civilizations. The points are only detectable using subspace technology, which means no race can activate its point and join the galactic community until it reaches the technical level of at least basic FTL.
 * The Transit Network of portal-trains in the Doctor Who New Adventures novel Transit by Ben Aaronovitch just covers the solar system (although the book describes an attempt at a Stellar Tunnel). Most people have a better idea of the shape of the network than of the physical system. It's a parody of The Tube, of course.
 * In Jonathan Strange and Mr. Norrell, Jonathan Strange discovers how to enter a mirror, traverse the world behind it, and come back out via another mirror. When his wife expresses concern about his safety, he promises to stop.
 * In Glasshouse by Charles Stross (and to a slightly lesser extent, Accellerando) wormhole technology is overwhelmingly prevalent, to the point where the protagonist of Glasshouse at one point has a jacket whose pockets are wormholes leading to convenient storage locations. The books largely cut out the spaceship middleman, and have vast numbers of deep space habitats all linked into one seemingly coherent whole whose internal geometry bares little resemblance to its actual distribution through space, or indeed to anything Euclid may have considered.
 * The Transfer Point network is, by and large, the preferred means of travel in David Brin's Uplift universe.
 * L-Space is sometimes used as a Portal Network in the Discworld novels. What is this L-Space thing? Well, "the relevant equation is Knowledge = Power = Energy = Matter = Mass; a good bookshop is just a genteel Black Hole that knows how to read. Mass distorts space into polyfractal L-space, in which Everywhere is also Everywhere Else." The more significant the knowledge contained in a library, the easier it is to get to -- meaning that a room with one book in it can be a major L-Space node, if the book leads to an entirely new science.
 * Before the (Much slower) FTL starships are developed in the Commonwealth Saga, the worlds are linked through wormholes.
 * Raymond E. Feist's series, The Riftwar Cycle, has the Hall of Worlds, which is a hallway with doorways that lead to thousands of different worlds. And Honest John's Inn. Not a lot of people know about it, so it's not often utilized, but when it is, it's used to travel vast distances very quickly. On a smaller scale, the rifts themselves, which connect the nearby worlds of Midkemia and Kelewan. Magicians of the Greater Path can also teleport to places they know very well, like their homes, or to a memorized pattern, such as would be set in the floor of important buildings. Then there are the "devices," which have not been properly named yet but are gold-colored orbs that, through a set of switches, allow the holder to teleport to several preset locations (but not back from those locations to wherever the device was activated). Four separate systems, which do not overlap. Plus whatever unexplained teleportation technique Pug, Miranda, and Magnus use, which is essentially the Greater Path magician one Up to Eleven. Feist must really like this one.
 * In the Wheel of Time series, there exists an ancient and largely abandoned network of Waygates, connected via a parallel dimension filled with bridges and paths known as "the Ways". They are abandoned because they were constructed by male Aes Sedai carrying the taint of the Dark One, and slowly became corrupted themselves, to the point that anyone entering them is liable to encounter the Black Wind. You do not want to encounter the Black Wind.
 * It's also implied that the Skimming platforms all go through the same space, it's just that they're so far apart that they never interact.
 * In Tobias Buckell's Crystal Rain and its sequels, the inhabited star systems are connected via wormholes in a way similar to the Vorkosigan Saga, including the key detail that only certain ships with special cyborg pilots can navigate through them. However, there are usually only one or two connections per system, meaning that the wormhole map of human civilization more resembles a subway route than a network of worlds. And an important plot point is that several wormholes have been destroyed, isolating worlds including Nanagada from the rest of civilization except by STL travel over hundreds of years, but.
 * First Contact with Earth, in John Ringo's Live Free or Die, is done by aliens bringing to the Sol System a node of their interstellar spacecraft travel network.
 * Most Precursors in The History of the Galaxy series by Andrey Livadny had these, as only a few races managed to develop hyperdrives. Thus far, no race seems to have developed both. Humans only discovered FTL travel by chance when the first extrasolar colony ship ripped a hole in space-time with its fusion-powered engines.
 * In the Heinlein Juvenile Starman Jones interstellar travel is done via "Horst congruencies", otherwise invisible, carefully plotted points in space where boosting the ship past light speed results in a "transition" to the corresponding congruency near your destination. (Screw up the astrogation by a whisker, and you wind up who knows where.)
 * In Peter F. Hamilton's Commonwealth Saga, habitable planets are connected by a Portal Network made of Wormholes linked together by railroad tracks that go through the wormholes. In the Void Trilogy, which takes place in the same universe, Ellezellin's Free Trade Zone consists of several planets connected by wormholes.
 * Attempted in the Dragonlance backstory. Back in the Age of Dreams, when all five Towers of High Sorcery still existed and the practice of magic flourished, the various high mages attempted to build a series of portals to link their Towers together to provide instant transport between them without the effort and inconvenience of standard teleportation spells. They metaphysically Dug Too Deep and ended up connecting their Portals to the Abyss. Soon after, the Dark Queen Takhisis tricked one mage into opening one of the Portals and releasing her, kicking off the Third Dragon War. After she was defeated, the Conclave took stock and realized that many of the mages involved in the Portals' creation had died in the war, meaning that without the secrets they had, the Portals could not be dismantled. The best they could do was lay down a nigh-impossible requirement to keep anyone from ever opening the Portals again. It didn't take.
 * The last book in Mikhail Akhmanov's Arrivals From the Dark series, appropriately called The Gates of the Galaxy, has one of these as a main plot point. It has been mentioned even in the first book that the ancient Daskins have left behind numerous ruins and artifacts, the greatest of which is a Portal Network that stretches to the nearby galaxies. One such entrance to the Abyss (or Hub) is what we call the Great Red Spot on Jupiter. When entering the Spot, ships must wait for the next "cycle" of the system, which will take it through the Mirror to the Abyss, a hub-like area outside of our dimension that contains hundreds, if not thousands, of such Mirrors. An untrained mind may find all this too much and suffer a mental breakdown. After the Daskins, only the Lo'ona Aeo know how to enter the tunnels. Also, there may occasionally be an encounter with an Eldritch Abomination-like Space Whale that feeds on mental energy. Luckily, these are vulnerable to ship-to-ship weapons, if you can get to them before your mind shuts down.

Also, normal Faster-Than-Light Travel method is, theoretically, even faster than the Portal Network, as it is possible to get anywhere in the universe in a fraction of a second. Unfortunately, jumps require extremely precise calculations, with distance and gravity affecting them. Otherwise, a ship may end up many parsecs off course or even inside a star or a planet. This is why all ships perform series of small jumps instead of a big one.
 * The Portico family in Neil Gaiman's Neverwhere live in an "associative house"; a collection of rooms and areas from all over the planet that have fallen through time and space to be assembled into an abstract patchwork building. Door and the rest of the Portico family are the only people with the power to traverse from room to room.
 * The Mat-trans in the Deathlands, Lost Technology in an After the End North America. The protagonists don't have the knowledge to use it, so just travel at random. In the spin-off series Outlanders it's revealed that the illness caused when using the technology is simply caused by not setting specific co-ordinates.
 * In Kir Bulychev's Alice, Girl from the Future, public transportation has taken this form by the year 2082. One of the main characters is a kid from the 20th century who ends up in the 21st. He enters what looks like a bus, only to realize it's not moving and exiting out the opposite door. He finds himself in a new location. Basically, bus stops have become a Portal Network. There are other methods of transportation, though, such as Flying Cars.
 * Sergey Lukyanenko's Spectrum takes place in modern times, with one addition. An alien race of Technical Pacifists calling themselves the Keymasters offers humans a chance to join the galactic community by having the Keymasters building Gates in major Earth cities that allow instantaneous transportation to a chosen destination. The payment for the use of a Gate is an interesting story told by the would-be traveler to a Keymaster. If the Keymaster enjoys the story, the traveler is allowed to pass. Any aggression towards the Keymasters is met with instant disintegration (whether or not the person is killed or transported is left open). The only condition the Keymasters set for the local governments is that no one is to be prevented from attempting passage. The Gates' interior is tailored to the current traveler's race. A human sees a desk with a regular computer that displays a catalog of available planets and Gates on them released by Microsoft (this part actually becomes a plot point). The traveler uses a keyboard and/or mouse to select the destination. There are no special effects. The traveler is simply told to exit the Gate. Several characters speculate that the Gates swap room contents in a several meter radius.
 * In Lukyanenko's The Stars Are Cold Toys The Star Shadow, the Shadow is a massive conglomeration of worlds near the galactic core joined by the Gates. However, unlike your typical Portal Network, the Gates don't take you where you think you want to go but to a location best suited for your current deepest desire. This is, as you can imagine, a bit of a crapshoot, as finding a specific world is almost impossible, and one should never trust one's own deepest desires. That is why there is a new organization within the Shadow that strives to build its own Portal Network, which is more typical. Also, neither the Gates nor the planets they're joined to can be destroyed.
 * The Lost Fleet series has two networks of portals. The old jump point system is a natural phenomenon that allows for FTL travel between star systems but the journey can still take months. The new human-built hypernode system allows for instantaneous travel between star sytems. This has led to the jump point network being only used to access systems not important enough to have their own hypernode built. When the titular fleet is cut off from the hypernode network by the enemy they have to use the jump point system to maneuver their way out of enemy territory and back to home space.
 * A massive part of the premise of Dread Empires Fall. These portals are spaced a couple of weeks' journey apart, though, so it can still take a few months to travel from point A to B.
 * The Spin trilogy features one of these, the Hypotheticals having installed an enormous entrance to one on Earth for unexplained reasons.

Film

 * Agents of The Adjustment Bureau can access a secret Portal Network through ordinary doors... as long as they're wearing a fedora.

Live-Action TV

 * In Andromeda it is possible to travel near-instantaneously between stars but not to a location without stars.
 * Babylon 5 used a series of fixed gates to access hyperspace, turning it into a Portal Network. Most larger military ships, and certain civilian ships, avert this by having the capability to create temporary access points on demand.
 * The gates also acted as navigation aids, with navigational beacons transmitted between the gates. Most ships traveling in Hyperspace were careful to Stay on the Path, or risk being Lost in Space . Specialized exploration ships and the bigger military warships carried specialized equipment for navigating off the beacon, but even those ships were wary about being too adventurous in hyperspace.
 * The Invisiportal Network in Power Rangers Dino Thunder.
 * The Stargate Verse, including Stargate SG-1, Stargate Atlantis, and Stargate Universe. The original Stargate movie has a single two-way link (other gates are not shown, but not ruled out either). The expansions give us a full-blown network.
 * The gates have a calibration system reminiscent of a rotary telephone. In the film the first six symbols are said to be constellations that act as coordinates in 3-dimensional space while the seventh chevron is the point of origin. The system in the sequels appears to be high-level automation: dial in the destination you want, the gate does the rest, Bob's your larval symbiote.
 * Until the pilot episode of the series, the humans' strategy is basically to cover their Stargate so that none of the bad guys can get through to attack. The flaw in this strategy is quickly pointed out: faster-than-light travel does exist, and the bad guys now know that there is a reason to come to Earth. Throughout the series, space ships and stargates (and, of course, space ships traveling through stargates) are both used as common means of travel. The stargates are faster, being truly instantaneous, but have several disadvantages compared to ships, such as being easier to prevent travel through, being too small to allow passage of anything bigger than a bus, and requiring preexisting gates that are hard to move (although it's not impossible).
 * An episode of Star Trek: The Next Generation featured the remnants of a network like this created by the powerful Iconians in the distant past. A much later episode of Star Trek: Deep Space Nine dealt with what might happen if the same technology fell into the hands of some bad guys. An evil artificial variant of such a network, known as "transwarp conduits", is created by the Borg.
 * Star Trek: Voyager also had a remnant portal network built by the Hirogen. It was powered by Black Holes!
 * It wasn't a Portal Network. It only allowed for communication, not travel. And the Hirogen only claimed it; they didn't build it.
 * Buck Rogers in The 25th Century featured Stargates (no relation) for interstellar travel. In-story they were relatively recent technology; the first pilot to go through a Stargate was Doctor Huer.
 * If you have the Key, you can use any door with a tumbler lock in this manner in The Lost Room miniseries. Opening any such door with the Key results in you entering Room 10 of the Sunshine Motel, which exists outside space/time. You can then close the door and open it in again to a location of your choosing. Better not leave anything (or anyone) in the Room when you leave, though.

Music

 * In Orbital's video for "Funny Breaks (One Is Enough)", the unnamed woman is able to travel between the interiors of suitcases.

Tabletop Games

 * In Warhammer Fantasy Battles the old ones built gates like this, then they collapsed and released the legions of hell on the world.
 * The Eldar Webway of Warhammer 40000. Also the Warp, to a certain extent. It has currents, storms, etc. that can render certain areas inaccessible, or make travel between certain points easier.
 * Fading Suns, influenced by the Heechee in this respect.
 * The Forgotten Realms setting has magical Portals in various shapes and distances. Has since been expanded out to everywhere with 4th edition: teleporting long distances requires a preexisting portal at your destination.
 * Sigil in the Planescape setting is packed with planar gateways, as are a few other planes in that setting such as the 1st layer of the Abyss. (Most of) the gateways will not appear unless you have the correct 'key' (which can literally be anything, from a broken skull to the correct color of eyeshadow).
 * The Plane of Mirrors from the 3E Manual of the Planes, an optional cosmology-addition for the D&D game, works like a whole bunch of mirror-to-mirror jumpgates.
 * An early issue of Dungeon Adventures described a network of towers, built long ago and damaged in places, that linked different parts of the world through magical gateways.
 * The Netherworld of Feng Shui is a mystical realm which allows travel through time via mystical portals that lead to different junctures in the past, present and future.
 * Eclipse Phase has two varieties of Portal Network. The more conventional faster-than-light travel is accomplished via the Pandora Gates, relics of The Singularity, but Brain Uploading allows casual interplanetary travel in the form of "egocasting", transmitting your mind at lightspeed to a given destination before (usually) downloading it into an on-site body. It's possible to ship your own body in cold storage, but depending on the distance it could take quite a while to show up.
 * In Starfire, star systems are interconnected through an elaborate network of naturally-occurring "warp points." Each warp point leads to another specific warp point in another star system. Strategic distances between star systems aren't measured in light-years, but in how many warp points you have to transit to get from System A to System B. Some systems are "dead ends" with only one warp point in them -- Sol is one such dead-end system.
 * Explicitly stated to either exist, or did exist in Dungeons and Dragons 4E. The settings being the interregnum between the previous great civilization and the next, some of the portals are still functional. D&D fans being who they are, this is one of the more contested point in the edition, citing it's too Video Games-like.
 * It exists in 3E too, it's called Sigil, the City of Doors. If you know which doors lead to which place in which realm, you can save a great deal of travel time even if you don't have magical means to travel the planes. Since some of those doors aren't doors in conventional sense, you can jump into, say, a closet in Material Plane, land in Sigil, walk a few blocks into a ruined stone gate down the road, and suddenly appear in Asmodeus' throne room.
 * Also in 3E/3.5, there are ways to turn other things into your own personal Portal Network. For example, a Blood Magus will eventually gain the ability to teleport between living things, and can even burst out like a Xenomorph. A less disturbing example is a spell that allows you to do this with trees.

Video Games

 * The indie 4X RTS Star Ruler has Remnant Gates, which allows players to teleport ships to anywhere on the map. However, regular slower than light travel and low range (and expensive) jump drives are common.
 * The entire point of Valve's Portal and Portal 2. Granted, the Portal Network only consists of two portals...
 * Unless you play the Co-Op version.
 * Independence War has no portals visible to the naked eye, but Lagrange points basically are portal networks as far as the capsule drive is concerned. Justified in that the energy required to create a "capsule" of isolated space-time (basically, a miniature universe) is impossibly high within normal gravity fields (Lagrange points are where two major bodies have their gravity cancel out), and independent "capsules" can only last so long before being reintegrated with the main universe. Because of this, pilots can expect to jump out of a Lagrange point just to turn around and go back in several times when traveling a long way.
 * The Mass Relay network from Mass Effect. Each Relay is possibly linked to dozens of others, all in different systems. It's widely believed that it was built by the Protheans 50,000 years ago, along with everything else related to the titular technology.
 * Three ancient, alien space gates appear in Earth 2160. It is implied that many others exist throughout the galaxy, given that the species that built them had been spread across at least three star systems and six planets.
 * Homeworld 2
 * Occurs in Achron's backstory as a transport backbone for the humans, who reverse-engineered the technology from some alien ruins. Also occurs in-game to a fashion if you're a fan of the 'slingshot' structure, which can shunt any units that approach it automatically to a point in space anywhere in a wide radius around it. If you build enough slingshots, you can chain them into teleport-bridges that can shunt your forces between all your bases.
 * Freelancer has a network of human-built jumpgates and naturally occurring jump holes as well as ancient Hypergates left behind by the Absent Aliens.
 * Ultima - Perhaps the oldest known examples of this are moongates in the Ultima RPG series. In an interview, the author of Ultima mentioned the movie Time Bandits as an inspiration for the moongates.
 * Fringe Gates in the RPG Fringeworthy. These gates also allowed travel through between alternate universes. They were an inspiration for Stargate SG-1.
 * The X-Universe series feature Jump Gates that allow spaceship to travel from sector to sector. It's the only way the races know how to travel between solar systems. Bad things happen when they disconnect.
 * Eve Online has a jump gate network. While ships do possess a warp drive, these merely accelerate the ship to several AU per second. Obviously, this is not fast enough for interstellar travel, though it is faster than the speed of light.
 * Player alliances can also build even faster PortalNetworks in systems that they control, to cut off several of the jumps required by the standard Portal Network to get between two points for friendly players.
 * The video game series Space Empires does this with 'warp points' at the outer edge of the solar systems, black holes, and nebulae. While naturally occurring, and depending on the game settings there can naturally be a path from any point A to any point B, late game technology allows these points to be created and destroyed, potentially radically altering the galaxy's effective topography.
 * The Scrin of Command & Conquer make extensive use of portal technology, though they have to land their forces in an area first and set up the portals once they arrive.

The Red Alert series also has the Chronosphere, which acts as a quirky kind of teleporter.
 * The star systems in the universe of the Wing Commander games are set up like this, although it is mostly only evident for gameplay purposes in Privateer and Privateer 2: The Darkening, because the main series has you flying only a few missions, in the entire game series, where one jumps to another system in their fighter.
 * Free Space has naturally-occurring, invisible things called jump nodes that act as subspace wormholes to other star systems. Notably, some of these are more stable than others, and the fact that the Shivans have more advanced subspace technology that allows them to traverse more unstable nodes causes massive trouble for The Alliance in the first game.
 * It's not the entire universe, but this is how Sabrina's gym works in the Pokémon games where it appears -- while there are nine rooms and no doors, you'll find a way to her eventually using the thirty paired teleport tiles.
 * In Air Rivals, travel between regions (and game instances) is done entirely via jumpgates. Other than excusing the Patchwork Map, it also affects gameplay by allowing spawn camping strategic bottlenecks.
 * Escape Velocity Nova's backstory is partially built around the aftermath of a Portal Network suddenly shutting down before the invention of FTL drives.
 * To clarify, the "shut down" was the result of many of them being deliberately blown up/destroyed. There are still a few in working order, however, and there are more that are wrecks (it's heavily implied in the manual that the gates were tough). There are two ways to get access to the hyperspace codes, although only one of them is accessible to all main storylines.
 * Starcraft - Rather than making buildings and units, the Command and Conquer Economy of the Protoss is actually used to build and power massive teleporters that bring over personnel and products churned out on their homeworld, Hand Waving the typical RTS Ridiculously-Fast Construction.
 * The control points in Unreal Tournament 2004's Onslaught mode function as a Portal Network, since the maps are actually way bigger than in most other FPS modes.
 * Several Duke Nukem 3D multiplayer levels had teleporters, and rockets fired into one would keep flying at the other end.
 * Quake with the slipgates.
 * Halo -- However, that game's portals couldn't transport weapons fire.
 * In Planescape: Torment, every doorway in Sigil is a potential portal to anywhere. Other portals around the multiverse are less common, but also lead back. Unfortunately each one plays by it's own rules, has it's own required key, whether that be an object, a sensation, a thought, an action. It's effectively a multiversal portal network, unfortunately the keys are so varied and sometimes non-obvious that even the Harmonium would never be able to catalog them all. And if they tried, Sigil-side portals would still be vulnerable to Dabuses constant restructuring.
 * This is used in the Mega Man Battle Network / Rockman.EXE games, which is expected seeing as how Everything Is Online. In the fourth game onwards, Rockman's homepage is linked to most or all of the internet squares, allowing for fast travel between the main internet overworld areas. However, Rockman's usually the only one who has these links on his homepage, if not the only one who actually has a homepage.
 * The Hivers from Sword of the Stars use a Portal Network to compensate for their lack of FTL. Portals use the Menisceal principle, using a gate to pull an object outside of the universe and put it back at another point. This only works when transferring between deployed gates, and they only work within a gravitational well with an exponentially larger pull than the object to be transferred (thus, packets of data can be sent from basically anywhere, while objects such as ships only work from portals located within a planet's gravitational well).
 * The human stardrive is a different type of Portal Network, allowing FTL travel through subspace but only between preexisting 'Node Fractures' which connect systems. The advantage is they don't have to lug a portal into position first. The downsides are that there's not guaranteed to be a nodeline to where you want to go, the trip isn't instantaneous and when you enter subspace you might attract...things.
 * The Zuul also use subspace travel, except their method involves drilling these fractures rather than using pre-existing ones. As you can expect, these are unstable and tend to collapse with time or heavy use. The Zuul are even more likely to attract...things given their brutal FTL method.
 * Interestingly, according to the novel Deacon's Tale, gate travel is only safe for Hivers, possibly due to their exoskeletal internal structure. Members of other races will feel very uncomfortable (you feel as if you're being twisted inside out) at the very least with death as a possibility.
 * Might And Magic VII's good ending sees the heroes being granted access to a hub for a Portal Network (the Gateweb) built by a Precursor civilization.
 * This was not the first time gates to other worlds came up in the series, but it was the first time it was explicitly made into a network: the titular Gates to Another World of II were exactly that (Gates to Another World), and the strange portal that brought Lord Ironfist to Enroth in Heroes I lacked an apparent control mechanism. Considering the Arc, Bright Star, CORAK and SHELTEM all use actual starships to travel around, the Gateweb appears to have been the Ancients' crowning achievement before the whole Kreegan mess...
 * The Myst games proved you could build a sophisticated portal-network for interplanetary travel out of books, rather than big metal rings or wormholes. It is a rule that you cannot link (go through a book) to anywhere in the world you are in. Each book is a link to a new and unique universe, not counting secondary books that are written with just enough to tie them to the original book for easy access from multiple places. Whether or not the universe existed before the book was written is an unanswered question both in-game, in-book, and in real life.
 * In Uru, the D'ni city of Ae'gura has several link-in points which warp to a smaller, centralized Age -- which, in turn, has links leading back to the main city, in various different places. Inspired by Riven.
 * A portal network similar to Uru appears in the Riven endgame. Also Direbo in End of Ages.
 * In Alundra an optional Sidequest opens one of these, allowing you to quickly travel to various places on the map. (But only if you had already been there on foot, making this also a Door to Before.)
 * The Cross Gates of Super Robot Taisen OG Saga: Endless Frontier are initially explained as a fact of life for the worlds that use them.
 * Prey uses this...sort of. There are many, many portals you travel through throughout the game, but they don't always connect to the same scale of reality - notably when you walk into a room with a small model of a planet, then walk through a portal and wind up walking around on the surface of that model planet - now at least a few hundred feet in diameter.
 * Morrowind features several versions of these, although in most of the cases they are only effectively portals -- they are people who will transport you via boat or giant bug to another town, but the travel takes place offscreen. There are also wizards who do the same thing teleporting you, and finally, there are old Dark Elf fortresses around the place, each of which has portals to two other forts, creating a network.
 * This is a defining story element in Sub Machine, as the teleporters are often the only way to get from one location to another.
 * Conquest: Frontier Wars often has several solar systems per mission, each linked by a naturally occurring wormholes.
 * The Spellforce games use one to justify the RTS/RPG style maps the game takes place on. The Portal Network itself is justified by the Endofthe World As We Know It reducing everything to un-navigable seas except for areas protected by glowy towers. The Big Good set up the Portal Network in the years between then and the beginning of the first game. Unfortunately, he didn't pay much attention to what got hooked up to what... so, for example, the Light and Dark elves got hooked up pretty directly, and so did the Undead and the Dwarves.
 * The network of jump points in Vega Strike is the only way to travel between the vast number of solar systems. Although the Backstory involves much use of Human Popsicle travel.
 * Averted in Galactic Civilizations where all the aliens used a Portal Network, until humanity developed Hyperdrive, which they then (rather idiotically) gave to every alien race they contact.
 * In the second Avernum trilogy the Avernites have developed their own Portal Network which connects Portal Pylons located across Avernum to the main portal.
 * The third Master of Orion game had wormhole travel as the only effective method to travel between star systems (a player could, in theory, travel through regular space, but this was far, far slower than going through the wormholes).
 * In the original game, a civilization could build stargates over a colony to provide instant travel between star systems.
 * In the second game, the player can research two types of Portal Networks. One simply sped up travel between colonies of the empire with the related tech, while the second made travel between your systems instantaneous.
 * Interstellar travel in Ascendancy uses "star lanes". In addition, some of them ("red") are much slower and barely can be used without an advanced version of the drive.
 * There is a trick to making lane travel instantaneous, which involves developing a device that, when fired at a star lane (or even a red link) momentarily destabilizes it, causing all ships currently using it to end up at their destination instantaneously. While this is a one-shot device, there is nothing to prevent players from building specialized ships filled with these devices and use them to create an interstellar highway of sorts. Imagine being able to move warships from one end of your interstellar empire to the other in the space of several turns (as opposed to hundreds).
 * Overlord I & II have networks centered on the Overlord's tower.
 * The Vangers universe consists of several interconnected universes making up the Lost Chain. Bonus points for the coridors being Lost Technology. Perimeter, being a prequel, expanded the universe.
 * Tales of Monkey Island Chapter 5: Rise of the Pirate God has various rips in the Crossroads that appear on LeChuck's ship, Club 41, a raft atop the Manatee Mating Grounds in the ocean, and a secluded island somewhere in the Gulf of Melange.
 * The Hall of Doors in Rayman 2.
 * Tachyon the Fringe has jumpgates linking sectors within a region (usually, a star system) and megagates linking regions. This is only for small ships, though. Capital ships are equipped with hyperdrives, although they still use the gates as navigation points. Additionally, there are one-way gates mentioned in the Backstory, like the one through which the Bora originally went.
 * In Sins of a Solar Empire, the Vasari can build late-game orbital structures called Phase Stabilizers, which allow direct phase jumps between two of them within a star system. As an additional bonus, the Phase Stabilizers can periodically bring in reinforcements from the remnants of the Dark Fleet. While this is significantly cheaper than building those ships yourself, you also have no idea which ships will come through. They're a high-tier tech, so if you see a Vasari player who's being defensive and has lots of civilian research centers, watch the hell out.
 * Temporary paths can also be established as a side effect of the Kostura cannon impact.
 * It's also a special ability of their Antorak-class marauders and Orkulus-class starbases. In case it wasn't obvious, the Vasari like this trope.
 * Wormholes as well.
 * Void Gates in Infinite Space provide instantaneous travel between sectors of space, even between galaxies.
 * In Runescape, after finishing a couple quests, you have access to the Fairy Rings. Enter one, and you're transported to the Fairy homeland, Zanaris, where you have access to the full network.
 * Also, the Spirit Trees (sentient trees that can teleport you to several Gnome-important places and the Grand Exchange), the Abyss (an Eldritch Location that leads to all Runecrafting altars), and possibly the teleportation jewelery, which are portable Portal Networks. Really, if you do enough quests, get your magic up high enough, do some tasks, etc, you can have several portal networks that link into each other, to the point where you can get to damn near anywhere with a couple minutes of walking.
 * Though not intended to be so, World of Warcraft has wound up with a network of one-way portals which can, in a pinch, provide quick travel to certain parts of the world. In addition, if you're a Mage, you're pretty much a walking portal network who can sell their services to other classes for a tidy profit.
 * You can make your own Portal Network in Minecraft. In the game, there's Another Dimension called The Nether, in which 1 block of lenght converts to 8 in the overworld. So it basically works like Hyperspace, if you wish to cover long distances between two points, to open portals to the Nether in these points, and then make a tunnel network in it, between the portals. Covering in-Nether distances with rails can shorten travel time even more.
 * Level 15 in the SNES version of Prince of Persia has a series of Portal Doors used to reach otherwise-inaccessible parts of the level.
 * Star Gates in Adventures of Rad Gravity. The final planet also has a difficult maze of teleporting doors.

Web Comics

 * The Gateworld in Dream Catcher, complete with a bunch of doors! Pity they only use two of them.
 * The Wormgate Network in Schlock Mercenary, ostensibly run by a corporation of various species, but actually controlled by the F'Sherl-Ganni Gatekeepers. Wormgates must be moved to new locations at slower-than-light speeds to initiate new worlds into the network. Wormgates can also . Early on in the comic's run, our heroes introduce a new hyperdrive called the Teraport, which eventually renders the entire network obsolete.

Web Original

 * The Jump Gates allow instellar travel in Nexus Gate. The Jump Gates have made space travel a mundane thing.
 * The Salvation War - The first thing the nations of the world do when they discover how to open portals into Hell is to funnel in modern weaponry and kick Satan out. The second thing they do is use Hell as a jumping-off point to mobilize the multinational Human Expeditionary Army more or less anywhere on Earth, putting the kibosh on Heaven's plan to destabilize the alliance by stirring up pocket wars on the mortal plane.
 * In Orion's Arm, some areas with very advanced technology are connected by a network of wormholes, which are very useful in a setting with no faster than light travel.
 * Sub Machine - The various SubNets of the Submachine, by way of, usually, teleporters.
 * The eighth episode makes clear that the reason you have been teleporting to quite a few ruinous areas is because.
 * In The Pentagon War, the five inhabited star systems are connected by pairs of linked "hyper holes", created by extremely expensive antimatter bombs.

Western Animation

 * Mighty Max has a ancient series of portals that can only be used by a magic hat. The portals are so complicated that you need to either memorize the entire system or have a map.
 * Transformers Animated has the Space Bridge Network, which allow instant travel across vast distances. It's stated that this is how the Autobots defeated the Decepticons.
 * The closet doors in Monsters, Inc..
 * The finale of Loonatics Unleashed ends with our heroes gaining control of a Portal Network, moving their headquarters there, and vowing to use it to protect the entire universe.
 * The Net is like this in Re Boot. Each system is a node and there are pathways between them. Then there's actual portals, which are temporary pathways between systems.
 * In Wakfu, 'Zaaps' are the network of portals used to travel across the archipelago.