The Milky Way Is the Only Way

In Speculative Fiction featuring faster-than-light interstellar travel, reaching other galaxies from the Milky Way (or fictional local equivalent, like the galaxy far, far away) is often shown to be impossible or unfeasible, regardless of how fast FTL drive is.

Of course, the distances between galaxies are much greater than the distances between stars in a single galaxy - the Milky Way is about 100,000 lightyears across, while it is about 2.5 million lightyears to Andromeda, the nearest spiral galaxy. If your FTL drive takes 100 years from one edge of our galaxy to the opposite one while going full tilt or your hyperspace shortcuts are limited by the need to return to realspace and assess your position after making a relatively short jump, then it is perfectly reasonable that you shouldn't be able to travel to another galaxy casual-like. Obviously this also extends to long-distance teleporters like Stargates, and the time is even longer should the gates be a sizeable distance from each other.

However, if your ship is capable of crossing the Milky Way in a single day, or your hyperdrive can simply open a shortcut between any two known locations anywhere in the universe, then there really is no excuse for this. Bonus points if there is some unconvincing Hand Wave as to why they don't go to other galaxies.

When done right (the "FTL takes 100 years to cross the Milky Way" version), it's an aversion of Sci-Fi Writers Have No Sense of Scale. Contrast to Small Universe After All.

Comic Books

 * Averted in Marvel Comics, where at least three extragalactic empires (The Kree, The Skrull and The Sh'iar) often interfere with Earth (and each other.) This is mainly because a "hyperspace nexus" happens to exist within our solar system.

Film

 * In the Star Wars Expanded Universe there are 'hyperspace routes' that ships go through, but they are only mapped through one galaxy: one could in theory travel to another galaxy, but it would take millennia without the routes. For most of the Star Wars mythos it's stated that there's no life outside of the galaxy; the Yuuzhan Vong eventually prove this wrong by invading.
 * Not only that, but apparently, the galaxy is home to more than one group of extra-galactic droid refugees that were running away from the Yuuzhan Vong (namely, the Abominor, the Silentium)
 * Star Wars also used the "barrier on the edge" excuse like Star Trek, calling it a "hyperspace disturbance" - and, like Star Trek, immediately dropped it. Particularly since it made no sense in a galaxy which had planned to send an extragalactic expedition years ago and had a serious scientific society dedicated to searching for extragalactic life...
 * As alluded to above, there WAS at least one attempt to leave their home galaxy. It was called the Outbound Flight Project, and consisted simply of a group of volunteers willing to take the many years necessary to travel between galaxies in hyperspace, and a gigantic ship with enough supplies to keep them alive through it. It was an unmitigated disaster, with no survivors- but because it was attacked and destroyed, not due to the infeasibility of the concept.
 * Although it apparently required a large number of Force users to allow them to breach the hyperspace disturbance.
 * There are also seven dwarf satellite galaxies very near (astronomically speaking) the main galaxy, which have been visited, at least by probes.
 * Though some earlier comments from ranking Star Wars continuity minions claim the view outside the end of The Empire Strikes Back claims it's a galaxy, the commentary on the Blu-Ray calls it a stellar nebula.
 * Pitch Black and The Chronicles of Riddick. The films don't mention galaxies but the novelizations contradict eachother. The novelization to Pitch Black by Frank Lauria inplies that humans have colonised several galaxies. it says that Riddick worked in the Sigma Galaxy and that Johns chased him across 3 galaxies. But the novelisation to The Chronicles of Riddick by Alan Dean Foster implies that everything takes place within one galaxy.

Literature
"He was being hopelessly anthropomorphic, of course. The entire drama concerned only the local group of galaxies. [...] The wolves might strangle sentience out of existence now, or they might guard a thread of it through its gravest crisis. And perhaps neither outcome really mattered, any more than a local cluster of extinctions on a single island would make any significant difference when set against the rich, swarming ebb and flow of life on an entire world."
 * The Foundation series by Isaac Asimov are all set within the galaxy. In the fourth Foundation book, someone wonders why - all places are the same distance away by hyperspace.
 * Actually, Asimov gives a pretty good explanation. Ships traveling trough hyperspace are affected by objects with mass that lie along the line that connects the starting and the ending point of the jump. The greater the mass or the distance between them, the greater the effect. This is the main reason why starships in the Foundation Universe use several small jumps instead of the single long one. And with every jump requiring several days to calculate the new jump coordinates, intergalactic travel would take a long, long time...
 * In the Robert A. Heinlein novel Time Enough for Love, the protagonist mentions how much of the Milky Way has been explored and settled but that Humans Are Special so that there have been a few spaceships that have attempted the "long" trip. Naturally, nothing is known about these ships as the author is well aware that the distance is just too huge for any word to get back (if anyone would really bother) for thousands of years (and that is with much faster than light spaceship drives).
 * Except that their Libby drives are apparently time machines as well (Only recently used that way because apparently nobody realized they were), and can arrive at their destination as just about any time they choose. And as nearly every character is functionally immortal and can have their personality stored electronically (A technique used to move between bodies too beat up to rejuvenate, easily adaptable to long-term storage), "on-board" time is nearly a non-issue. The only reason nobody's doing it that way is because they're too stupid to realize they can.
 * Samuel Delaney wrote the excellent story The Star Pit where only people with a specific set of psychological issues can handle going outside the galaxy, even though interstellar travel is ridiculously convenient.
 * Inversion: In Alan Dean Foster's novel Design for Great-Day, the Solarian Combine is a super-advanced mental and social amalgam of multiple species working together in harmony who routinely visit other galaxies in their ridiculously fast spacecraft.
 * In Robert A. Heinlein's Glory Road, the Empress of the Five Galaxies rules over, well, exactly that. The necessary Faster-Than-Light Travel is accomplished by means of Portal Network.
 * Night's Dawn trilogy, upon discovering the sleeping god at the end of the last book, and theorizing that it is capable of intergalactic travel, everyone is shocked, despite living in a society that has known FTL travel for more than 500 years.
 * Given that it took several months and hundreds of small FTL 'jumps' for the main characters to travel the 1300 light years to find the Sleeping God it's not so surprising that they'd be shocked.
 * Averted in Alastair Reynolds' Revelation Space story Galactic North. Note that in the Revelation Space universe, there is (effectively) no Faster-Than-Light Travel.
 * From Redemption Ark:


 * Predictably, The Hitchhiker's Guide to the Galaxy is apparently set entirely within The Galaxy. Despite all the various forms of faster-than-light travel, extradimensional beings, and travel driven by improbability.
 * There is one point in the radio show where the cast are escaping from Milliways and find themselves headed into intergalactic space—promptly running for the escape pods. Mind, there were other reasons not to want to be aboard that ship at that particular time.
 * Related to this: when the characters are searching for the real power behind the galactic throne, someone says "maybe he rules the whole universe" and this is thenceforth assumed to be true.
 * Inverted (or something) in Vernor Vinge's Zones of Thought. All technology, including FTL travel, works better as you get farther from the galactic core. This means it's impossible to get to the middle of the galaxy, because your ship will continually slow down and eventually stop. Intergalactic travel should be possible, except that the outer reaches of this galaxy are controlled by technological AIs who have ascended to near-godhood, and they don't let anyone past them.
 * Subverted in The Last Legionary young adult series by Douglas Hill. The "Overlight" FTL drive used by spaceships in the stories is perfectly capable of getting a ship to another galaxy in several months but extended stays in Overlight drive humans insane making it impossible to have a functioning crew at the other end of the trip. At the end of the series Keills alien sidekick Glr (from another galaxy herself) reveals the suspended animation allows the problem to be bypassed allowing her to potentially take Keill to visit her home galaxy.
 * In Iain M. Banks' Culture novels, it's explained that the Grid—the barrier between this universe the other ultraverses/infraverses ships use to travel—changes properties in extra-galactic space, making ships travel slower. Although, it didn't stop the Sleeper Service from trying.
 * In Mikhail Akhmanov's Arrivals From the Dark books, all known galactic races utilize the "contour" drive for instantaneous FTL travel. It works by shifting the ship into another universe and then back into a new location. The drive consumes very little power but is prone to burn-outs, especially smaller models. However, jumps require extremely precise calculations, and strong gravity fields can drastically affect them. That is why most prefer to make a series of shorter jumps than a single long jump. Only the Orion Arm (our arm) of the galaxy is explored by most of the known races. The Faata hail from the Perseus Arm but don't know much about the Orion Arm. It is common for Faata in the first two novels to take the long way around instead of jumping directly through the Void (area between the two arms with no stars). During the Void Wars, however, the Faata make several attempts to travel through the Void instead of around it. It is possible that the Daskins have travelled outside the galaxy. Most races assume that all of them left the galaxy long ago, which would explain their absence.
 * In Andrei Livadny's The History of the Galaxy series, only a (relatively) small chunk of the galaxy has been discovered by humanity and all known races. While all alien races are, at least, millions of years old, the fact that they relied on Portal Networks and never invented the hyperdrive means that their expansion was extremely slow. Humans, on the other hand, have spread our in all directions, but only have several hundred colonies not too far from each other. Also, the nature of Hypersphere implies that it is limited to our own galaxy. No one ever brings up the idea of going to another galaxy.
 * In Vladimir Vasilyev's War for Mobility duology, a newly-discovered portal to another galaxy is a major plot point, with its discovery sparking an interstellar war. Without it, FTL travel is way too slow to cross intergalactic distances. It is implied, though, that the Precursors who created the portals were able to do so, as they would've had to fly a portal to the other galaxy first in order to use it.
 * Also, in the novel Death or Glory, which takes place several hundred years prior to the duology, The Alliance is being slowly crushed by a race of Space Whales from outside the galaxy.
 * Perry Rhodan started out with this (well, to be fair, it started with the first in-universe moon landing and mankind needed some time to even spread out into the galactic neighborhood)...then came the classic Andromeda arc (issues #200 - #299), which showcased the difficulties of trying to even reach enemies in another galaxy with the technology available at the time, notably FTL drives that burnt out and needed to be replaced too soon to cover the entire distance. (Besides the creation of new multi-stage, multi-drive ship designs that used and dropped their drives one after the other, the main answer was the successful hijacking of several of the enemies' own intergalactic transmitter stations.) Even much later, 'routine' intergalactic travel remains pretty much limited to the familiar cosmic neighborhood and actual long-distance expeditions are pretty few and far between.
 * E. E. "Doc" Smith averted this in his Skylark of Space space-opera, by the simple expedient of having the heroes discover (to their surprise) that Einstein was wrong and you simply can keep right on accelerating past light-speed. Eventually, the scale of this gets so big that the heroes have a map of what they call the 'first universe', the super-system of galaxies that includes every single galaxy known to Terrestrial astronomy and many more, it turns out that galaxies themselves form disk-shaped, spiral-armed associations on a scales of hundreds of billions of light-years. (It is explicitly stated that there are many, many such 'universes' in our spacetime, and reaching those other mega-clusters of galaxies is about as hard as intergalactic travel is usually portrayed as being). This being pre-digital age science fantasy, the map is analog, a physical representation of the galactic assocation 600 miles across.
 * 'Doc' handled intergalactic travel in a tad more restrained way in the Lensmen series, in that, the inertialess drive and cosmic energy power system, onc the heroes have them, can and do enable intergalactic passages in reasonable time, and it isn't long before somebody does it. It so happens, however, that for astrophysical reasons, most galaxies are barren of planets, only two, the Milky Way and Lundmark's Nebula, are planet-rich.
 * At the other end of the scale, in Spacehounds of IPC, 'Doc' Smith portrayed a space-travel setting confined to the Solar System, and there was no sign that interstellar travel was coming anytime soon.
 * The third novel in Sergey Lukyanenko's A Lord From Planet Earth trilogy reveals that, while are able to cross galaxies, it was a complete accident that a ship ended up in a faraway drawf galaxy and stumbled on a race of Human Aliens with Blue and Orange Morality. What follows is an intergalactic war that leaves  desperately scrambling for allies. They have set up a "No Warping" Zone on the outskirts of the Milky Way in the direction of the dwarf galaxy that forces the enemy ships to drop out and be attacked by  forces. Played straight in the first two novels, where precise hyperspace coordinates are required in order to make FTL jumps. The only coordinates available are those left behind by the Seeders.
 * In another of Lukyanenko's series, Line of Delirium (inspired by Master of Orion) the main character speaks with an Alkari representative who reveals that the entire Alkari race is making preparations to leave the galaxy for another one, as they have given up trying to conquer this one (they were the first known race to develop interstellar travel but waited too long to spread out). Why they think the other galaxy will be empty of life is not mentioned.
 * In the William Shatner novel Beyond the Stars (a part of his Quest For Tomorrow series), the protagonist Jim (Does This Remind You of Anything?) is sent on a colony ship. The back cover of the book claims that the ship is called Outward Bound and is, in fact, a Generational Ship heading for another galaxy. This is, however, a case of Covers Always Lie. Not only do they get the name of the ship wrong (it's similar, though), but it's simply heading for a world far away from human space, but no one ever mentions another galaxy. It's also revealed in the next book that.

Live Action TV

 * In the original Star Trek series, when traveling across the galaxy seemed to take just a few days or weeks, they had the "Great Barrier", a mysterious energy field blocking intergalactic travel. The Great Barrier turned up occasionally as a plot point in some of the Expanded Universe novels, but for the most part, the later series dropped that idea and changed warp speed from Traveling At the Speed of Plot to a mostly consistent "100 years to cross the galaxy" rule to explain the lack of intergalactic travel, like in Voyager.
 * There is at least one species that comes from Andromeda, but takes 300 years or so to send a ship across the void. (These are the guys with the weapons that make people into salt cubes and back again).
 * The Planet Killer of the TOS episode "The Doomsday Machine" was believed to be extra-galactic in origin.
 * One of the Expanded Universe novels (written by William Shatner) mentions a ship that accidentally ended up halfway to Andromeda galaxy and encountered an Eldritch Abomination that was already on the way towards us. This was, however, the result of the ship ending up in a transwarp conduit connecting the two galaxies. Other EU novels include discussion on how to explore out there, mostly settling on AI being the only option.
 * Another novel describes that the 2 barriers (surrounding the galaxy and at its center) were created by the all-powerful Q to keep a Big Bad from re-entering the galaxy (and another's head trapped in the center). The side-effect of causing psychics to go crazy is unintentional.
 * It's later stated explicitly in TNG that the Federation has only explored less than twenty percent of the Milky Way.
 * This was before both Deep Space Nine and Voyager, which examined the Delta and Gamma Quadrants, but given that a major mission of Star Fleet is exploration, and Star Fleet had been around for hundreds of years by this point, it's pretty likely that Federation didn't significantly increase this number by the end of those series. Trying to not die of Borg attacks or running out of resources (Voyager) or survive all out war with The Empire (DS 9) probably didn't help exploration much either.
 * Star Trek Online (which is set decades after Voyager) allows much faster travel through the use of Transwarp, but they need a Transwarp Hub at the destination, so unless there is a compatible Transwarp hub in another galaxy, good luck using it to get there.
 * Averted in Stargate SG-1: extragalactic travel is possible with Stargates, it just requires more than ten times as much power as usual (roughly matching the distance difference) or having a long bridge of Stargates stretching across intergalactic space, as Carter and Mckay eventually created, and they have access to ships which can make the journey in a short enough time to make it no real intense issue.
 * Two other galaxies make regular appearances, in fact- the last two seasons of SG-1 feature an (unnamed?) Ori-ruled galaxy, and Stargate Atlantis is set principally in the Pegasus galaxy, with the Milky Way being the one that puts in cameo appearances.
 * Don't forget the Asgard galaxy.
 * The recent Stargate Universe series allows the characters to travel farther than before using a stargate powered by a planet's core, ending up on a ship that has been jumping from galaxy to galaxy for over 100,000 years.
 * While this ship is capable of jumping between galaxies (and indeed, galactic clusters over time) via FTL, it requires the ship's entire power reserves to do so. While the starship Destiny can recharge itself by diving into stars, the distinct lack of stars between galaxies means that if Destiny falls short, it must drift at sublight speed for the rest of the trip - often, over the course of millennia.
 * Also, don't forget the Asgard who can cross these distances within minutes or the new wormhole drive allowing an entire city to be instantaneously moved precisely to Earth's orbit from way outside our galaxy.
 * Averted in Andromeda, where the old Systems Commonwealth encompassed two other galaxies besides ours (Andromeda and Triangulum). The nature of Faster-Than-Light Travel in this setting slightly justifies this, as luck has a lot to do with how fast a ship gets to its destination. Similar to Star Wars, well-traveled routes tend to create trade lanes of sorts, as slipspace is more stable along them. This is why there are no automated ships in the series. Since machines (even AIs) are incapable of simply guessing, they may end up stuck in slipspace for decades. This happened to the Andromeda Ascendant after her entire crew was killed by the Magog and she had to flee back to the Commonwealth.

Tabletop Games

 * In Warhammer 40000, the Imperium is prevented from going beyond the galaxy by the Astronomican (a psychic lighthouse needed for reliable warp travel) not being powerful enough to guide them that far. The Eldar are constricted by the infrastructure of their webway tunnels, Ork warp travel is haphazard and the Tau are limited to a form of FTL considerably slower than true warp travel. The Tyranids come from another galaxy, but they probably travelled very slowly between the galaxies. What isn't explained, however, is why the Necrons and their C'tan masters went into hibernation after scouring the galaxy clean of most life millions of years ago, given that their inertialess drives (fast FTL without entering the Warp) and immortal shells give them the means to travel to other galaxies even if it takes thousands of years, and the prospect of killing more living gives them a motive.
 * In Nightbringer it is mentioned that "whole galaxies had died by their command", or something like that. The Necrons hid to escape the Enslaver plague. There were still plenty of people trying to kill them - the Nightbringer's flagship is defeated by a large alien fleet. I wonder why the Nightbringer didn't just phase out. Perhaps their enemies can go at extream speeds also.
 * This troper would like to add that the Enslavers rival the Tyranids in terms of Nightmare Fuel.
 * Also, they have no guarantee that they would even find another galaxy possessing sentient life, which the C'Tan had grown so accustomed to feeding on that they wouldn't accept any other food source. Better to remain in a galaxy where such life still exists (the Old Ones, Eldar and Orks hadn't been wiped out, just severely depleted by the Enslaver plague; the C'Tan wouldn't have wiped them out, since they considered them a delicacy) and wait for it to be rejuvenated (and hopefully for the Enslavers to die out).
 * How do you know they didn't? There are C'tan that are still here, but that doesn't mean none of them left.
 * The latest Necron codex retconned the whole thing away. They don't have real FTL but just hack the Eldar webway, using their immortality to take longer trips at sub-light speeds. The sources that said they had this ability were always from other races, they just misunderstood what they were seeing.
 * In Traveller only a small part of the Milky Way is known by Emperor Strephon's time.
 * Inverted by Palladium's Phase World setting. The FTL engines used are slowed down by gravity interference from stars and suchlike, meaning that it's often just as fast moving between the closely spaced galaxies as it is crossing the same one.
 * Justified in BattleTech by the low FTL speeds of JumpShips. Yes, they can make near-if-not-quite instantaneous 'jumps' over up to 30 light years at once...then the drive core takes at least a week to safely recharge, requiring either a nearby star to collect the energy via solar sail or eating into the limited fuel reserves if using the ship's own power plant to do so.

Video Games

 * The wormhole that brought humanity from The Milky Way to New Eden in the backstory of EVE Online collapsed millenia before the game's setting. The limits of stargate construction in the EVE 'verse make it impossible to create a man-made link back. This limits gameplay to one galaxy, though you can see the wormhole's remains in the New Eden solarsystem.
 * The recent addition of ubiquitous wormholes appearing and disappearing throughout the galaxy have granted access to another galaxy, where a race called the Talocan have left their vicious Sleepers to guard their advanced technology. The new wormhole systems are dangerous and lawless, but exploiting them can be very profitable.
 * Its also speculated that the Sleepers were left behind or are the remnants of Humanity that was cut off when the EDEN wormhole collasped...
 * Mass Effect is set in the Milky Way and none of the spacefaring civilizations in it are able to travel to other galaxies. This is because the "Mass Relays" which everyone uses to get around the galaxy are Black Box technology left behind by the extinct Protheans, and not only does nobody know exactly how they work, a past Bug War has made The Federation very cautious about activating relays without knowing where they lead.
 * The real issue is the limitations of non-Relay FTL technology. Mass Relays allow instantaneous travel across hundreds to thousands of light years, but you can only travel to a Relay within that range, which obviously limits you to the Milky Way. Non-Relay FTL travel is so slow (only 10 light years a day, at best) that it takes forever to get anywhere, and your effective range is limited by the need to discharge the ship's drive every 48 hours on a planet or in a sufficiently powerful magnetosphere. More than 99% of the galaxy remains unexplored.
 * Free Space uses a naturally-occurring portal network to jump ships between star systems, but a jump node to another galaxy is never found, or even hinted at (Epileptic Trees as to what exactly the Shivans did to Capella notwithstanding). On the other hand, humanity hasn't exactly explored very far in Freespace; the GTVA's territory only consists of approximately 40 star systems. They've barely started exploring the Milky Way, let alone other galaxies!
 * So Massively Averted the MMO Space Invasion- travel between galaxies is not only possible- it is rather common at higher levels.
 * Justified in the Master of Orion series, as ships can only travel so far from your territory, making it quite understandable why other galaxies would be out of reach. (It is possible to research fuel cells with unlimited range, but these come so late in the game it hardly matters.)
 * Like the MOO series, Galactic Civilizations also restricts the range your starships can travel from your systems, again making it understandable why other galaxies would be out of reach.
 * In Halo, it takes a really long time to get anywhere with slipspace, so that explains why they haven't ventured between galaxies. The only known species to cross galaxies are the Flood, who came from another galaxy, and the Forerunner, who built the Arc beyond the rim of the Milky Way. There's still plenty of stuff in the Milky Way that humanity hasn't found during the main timeline of the Halo series, such as the titular Halo rings (still haven't seen 5/7 of them), or any of the Covenant homeworlds.
 * The gameplay of Tachyon the Fringe is centered around tachyon gates (or tachyon coil generators, to be precise) that connect all of known space (actually, only a few dozen systems). Close to the end of the game, a news report informs the player about newly-invented tachyon wave generators, vastly increasing the range at which capital ships can travel (fighters still need static gates for FTL travel).
 * Averted in the Ratchet and Clank series, where the second game in the series actually takes place in a different galaxy than the rest of the series. Getting back to the first galaxy in the third game takes as little effort as installing a new warp drive in their space fighter.
 * Played straight in the first Homeworld game, but averted in the stand-alone expansion. In the Cataclysm expansion, the Naggarok is an experimental extragalactic ship sent by an unknown race millions of years ago. On the way, it has picked up a hitchhiker in hyperspace, which ended up being a sentient virulent lifeform known as the Beast. The Naggarok is way more advanced than anything anyone in the galaxy has, including an intergalactic hyperdrive, an inertialess sublight engine, and disassemble weapons that can take any ship apart in seconds. The Bentusi, afraid of the Beast, decide to flee the galaxy for another one using a powerful slipgate. Since the sequel almost completely ignores the expansion, this trope is once again in effect, except, perhaps, the fact that most of the Bentusi are gone.
 * Averted in Infinite Space, where Void Gates connect the two Magellanic Clouds, and the characters eventually travel to.
 * Even with the strongest engines available in Spore, you can only cross a few parsecs in a single jump, and each jump has to end near a star or spacial anomaly. Intergalactic space is just too barren to cross.

Webcomics

 * Schlock Mercenary has a footnote on why wormgate and teraport travel outside the galaxy is hard to impossible.
 * Some of that explanation only applies during the story unfolding when it was written. Since then (or, more accurately, after it never happened thanks to time travel), an AI with immense resources at its disposal actually has gone to Andromeda—and turned it into Space-Australia.
 * This is probably only possible if you have the time to move a wormgate to the other galaxy at sublight speed, over millions of years. Of course, considering the resources the Gatekeepers and Pa'anuri had, it would stand to reason that the Milky-Way/Andromeda connection wasn't the only one...

Web Original

 * In Orion's Arm a total lack of FTL has prevented anyone from leaving the Milky Way yet, as the name implies no one has even reached another arm of the galaxy. However a message from the Triangulum Galaxy has been picked up and massive telescope arrays have seen planetary scale building projects occurring in other galaxies.
 * Not only did the Triangulum civilization send a message describing their entire civilization, they also told of a ten light-year wide object with the mass of billions of stars and made up of the artificially imploded remains of an entire galaxy headed toward the Local Group of galaxies. Not only is it crossing intergalactic space, it's also coming from an entirely different cluster of galaxies.