Absent Aliens

""There are the stars -- doing their old, old crisscross journeys in the sky. Scholars haven't settled the matter yet, but they seem to think there are no living beings up there. Just chalk...or fire. Only this one is straining away, straining away all the time to make something of itself.""

- The Stage Manager, Our Town

Mankind has explored the galaxy, and in some stories the universe, and it turns out the truth isn't out there. There are no aliens, at least intelligent ones—although there may be a few cursory alien plants and rodents or perhaps a Monster of the Week.

Done for a variety of reasons:
 * Not every sci-fi plot requires aliens
 * Avoids Rubber Forehead Aliens, and saves having to think up decent Starfish Aliens
 * Isolates humanity in the depressing void of space
 * Makes humans even more special
 * Saves on the effects budget.
 * Makes it easier to make characters relatable and believable.
 * Is consistent with the fact that no aliens have yet been found. (See Mohs Scale of Sci Fi Hardness.)
 * In an attempt to be different and appeal to those who "don't like sci-fi".
 * Even if aliens did theoretically exist, in settings where the population is confined to a single star system and there is no FTL, neither humanity nor the aliens would be in any position to encounter the other.
 * Theoretically, intelligence could be a rare evolutionary fluke, rare at least elsewhere in the Milky Way. Even if intelligence evolves on other planets, it may be extinct by the time humans leave the Solar System, or alternatively, humanity could be extinct by the time aliens leave their home system. Thus, even interstellar civilizations may be separated by immense distances or timescales, and unlikely to interact.

The Monster of the Week role will generally be handled by humans, genetically engineered monsters, and robots.

Compare Invisible Aliens, in which aliens exist but are being hidden or removed by Applied Phlebotinum.

Thus far true in Real Life, for a more detailed explanation, read about Fermi's Paradox over at The Other Wiki, as it's a good introduction to the topic.

Anime and Manga

 * Cowboy Bebop: There was passing reference to life on Ganymede, but nothing intelligent, and it may have only been there after terraforming. Those sea rats are damn tasty. Or at least the people that sell it as some sort of a delicacy say so (Jet says otherwise).
 * The "aliens" in Crest of the Stars, known as the Abh, are really genetically-engineered humans.
 * Kiddy Grade, set within one galaxy, and not only no sentient species, no other life at all has been found so far.
 * Legend of Galactic Heroes also avoids aliens, focusing mostly on human-to-human interaction and history.
 * There might not be any aliens in Vandread, but that doesn't stop Dita from trying to find them. It's also played with; the people of Ma-Ger and Tarak consider each other to be hostile aliens, even though they're really just male and female humans trying their damndest to be One Gender Races through gene manipulation.
 * One of the things which initially made Mobile Suit Gundam stand out from the pack of sci-fi mech series of its day was the total lack of space aliens. This was primarily done because the writers felt that having alien villains would make them too hard to relate to; they wanted the show's central conflict to be one in which both factions had understandable motives. Other Gundam series have carried on this tradition, with all the major conflicts being between humans. Mobile Suit Gundam SEED has some fossilized remains of Space Whales, but that's about it.
 * The 00 movie reverses this trend, introducing liquid metal funnel / bit shaped aliens as the antagonists.
 * Lampshaded in Gundam AGE,

Film

 * Forbidden Planet: The Krell, the ancient race that once inhabited the planet, have been extinct for millennia. Only their technology remains.

Literature

 * Inverted in The Alien Chronicles: it's the humans who are absent.
 * The classic prose example is Isaac Asimov's Foundation series. There were no aliens in it because of a meta-reason: Astounding Science Fiction editor John W. Campbell wanted stories with human supremacy over aliens and Asimov decided to bypass this demand by not having aliens in the series at all.
 * Additionally explained in Asimov's oft-forgotten early novel, The End of Eternity, which connects to many of his other stories including Foundation, and has as a main plot twist the revelation that if the human race doesn't grow up in the next 10 million years or so and take over outer space, other species will apparently evolve sufficiently to take over all the good planets, leaving mankind stuck on Earth to wither and die out.
 * However, Foundation and Earth, the last Foundation novel which was written years later (and not long before Asimov's death in 1992), brings up the rather good question of, regardless of their apparent absence here, whether or not species from galaxies other than the Milky Way might perhaps not only exist, but be a potential threat if humanity doesn't band together enough - which is the reason, albeit only subconsciously realized, that the protagonist chose the "Gaia"-style path for humanity. Further, Foundation and Earth also brings up the point that genetically engineered humans who have been so radically changed from baseline humanity could sufficiently meet the requirements of being called "aliens" i.e. the Solarians.
 * In the Second Foundation Trilogy (written by Bear, Benford, and Brin), it's tangentially revealed that Asimovian robots (designed to protect humans, and only humans) are responsible for the situation, having been required by their programming to carry out innumerable genocides, since the aliens might have been a threat.
 * Stephen Baxter's Manifold series of (mostly) so-hard-it-hurts Science Fiction revolves around the Fermi Paradox, with each (Alternate Continuity) book providing a different resolution. In Manifold Time, there really is no other intelligent life in the entire universe. Manifold Origin is similar, except it's set in a multiverse with an intelligent species in each universe.
 * Lois McMaster Bujold's Vorkosigan Saga is a roughly 30th-century Milky Way with no sentient aliens to speak of (though there are alien plants and animals); however, after nine or ten centuries of diaspora, many of which involved various genetic engineering concepts, humanity has undergone speciation to the point that "the aliens [are] us."
 * Similarly, the Vatta's War series be Elizabeth Moon has humanity spread out to such an extent that Earth isn't even mentioned. Humanity is still the same species, but there is a fair amount of augmentation, both organic and technological, being done and baseline improvements are made to genetic code.
 * In Frank Herbert's Dune series alien plants and animals exist (including the iconic sandworms), but nothing sentient. Rather, the closest to "aliens" are genetically modified humans and animals. These creatures take a variety of shapes, some almost unrecognizable.
 * The CoDominium universe by Jerry Pournelle. In the Falkenberg Legions the series features no intelligent aliens. In fact, the CoDominium series is largely lacking aliens until The Mote in God's Eye, which is set far into the future of the series and makes First Contact.
 * Author David Brin has argued that the galaxy is so large, and the history of the galaxy is so long, that its actually likely that only one sentient species arises in the galaxy at a time. They live for a few million years, then die out, and as they are dying out, the next species is arising on some far-distant planet. Brin's other treatments of this idea range from exultant (Crystal Spheres) to mild fearsome (Lungfish).
 * Robert J Sawyer's Quintaglio Ascension trilogy : Although there are several planets with intelligent life, there is no life in the universe that can't have its origin traced back to Earth - at least not in this iteration of reality.
 * Technically averted, but played straight in spirit within Honor Harrington: There are sapient aliens (twelve known species), but humanity has settled many thousands of planets without encountering any aliens capable of building spaceships or other modern technology. There is a short story featuring evidence there once might of been one, but long since died out.
 * Sort of happens in K. A. Applegate's Remnants series: there are aliens, the Shipwrights, and three other species, at least two of which the Shipwrights created. However, these three species are apparently exterminated by, and it is implied the Shipwrights may be dying too. The penultimate book involves spending the rest of their lives looking for some other form of life but never finding anything more than bugs.
 * Just about everything in Dan Simmons' Hyperion is more or less a result of human works. Slightly averted as the books sometimes mention aliens, even intelligent ones, although all of those have been driven to extinction or were simply wiped out by humanity.
 * Played straight initially, then subverted with a vengeance, in The Stainless Steel Rat series. Aliens are completely absent throughout the galaxy up until one book where every kind of grotesque alien monster pops up out of the woodwork. They were just hiding all that time. Seriously.
 * Played with in The Stainless Steel Rat Sings the Blues, where Slippery Jim Di Griz, the titular Stainless Steel Rat, is send undercover to find the first recorded alien artifact.
 * Mildly averted in David Drake's RCN Series series - there are four sentient species, but their metabolic and atmospheric requirements mean none of them can coexist on the same planet without being in an atmosphere tank. One sentient alien appears in one throwaway scene of one book.
 * In Embedded, humanity has colonized hundreds of worlds but found no sign of intelligent alien life anywhere.
 * Zig-zagged in The Golden Age by John C. Wright. Biological engineering has reached the point where (formerly) human beings are able to turn themselves into what basically amounts to Starfish Aliens as compared to "traditional" humans (amorphous blobs, Hive Minds, an entire sub-culture of living biological Squick, and sentient ecosystems, to name a few) but no humans have ever encountered actual extraterrestrial life and have pretty much given up looking, until something from the outside starts to cause trouble for the main character
 * Played straight in Lem's Tales of Pirx the Pilot.
 * Subverted a lot in the Revelation Space series by Alastair Reynolds. There is various odd alien fauna and flora, but there are no living alien races comparable in intelligence to humans. However, human archaeologists continue to find the remains of several highly advanced civilizations all the time. More worrying is the fact that they all seemingly became extinct shortly after they discovered interstellar flight and started exploring deeper space. There turns out to be a reason for that - and the author uses it to cleverly explain why the Fermi paradox seems to be in effect in the first place. The Fermi paradox itself is the driving mystery behind the events of the series.
 * The In Death series. There is space travel in Robbs' 21st century, but it's mostly background, and there's no mention of non-human life. (Aside from the complete monsters Eve chases)
 * Last Legionary: Although there are a wide variety of humanoid forms; they're all genetically human, just mutated by the effects of their respective environments. High-gravity worlds get shorter, heavier humans and so on. The only genuine alien is Glr, and her species isn't from the same galaxy.
 * There are many planets in The Diving Universe, but they're all populated by humans. Not even the nomadic Fleet, in all its travel across known space, ever found an alien intelligence.
 * In the Matador Series humanity has colonized most of the galaxy's Earthlike planets and found nothing sapient.

Live-Action TV
"Inara: Do aliens live among us? Kaylee: Yep. One of them's a doctor."
 * The 2000s Battlestar Galactica has no aliens: just robots, clones, and the occasional 'angel'.
 * But let's be clear here: Humans.
 * Also, there is absolutely some kind of intelligent god-like being served by messengers.
 * Firefly, ostensibly because humans make more interesting foils for humans. Lampshaded when a "genuine alien" at a sideshow in one episode turns out to be a mutant cow fetus in a jar, with some creepy lighting thrown in for good measure. Word of God confirms the nonexistence of aliens in this particular universe. The fact it is set in a single star system is also a factor.


 * The Red Dwarf verse contains no alien life, and in the novels it's explicitly stated that Earth has been proven to be the only place in the universe where life appeared. In the early seasons this added to the isolation and paranoia of the main characters. Later, the writers added so many robots, genetically engineered monsters, and things evolved from Earth life-forms that it scarcely made any difference.

Tabletop Games

 * The BattleTech Universe is renowned for its lack of intelligent aliens. The lack of aliens allows its Black and Grey Morality of interstellar politics between human groups to thrive. There are primitive aliens, but they were discovered in a unknown system by a Jump Ship misjump (read: they'll never interact with the rest of the universe), and they only appear in one novel, Far Country.
 * Attack Vector: Tactical features only humans fighting other humans. These humans have only explored and colonized a relatively local part of interstellar space, though.

Video Games

 * When Anarchy Online was first released, humanity was thought to be it for intelligent life in the galaxy, though the backstory novel Prophet Without Honour did include at least one being that was not at all human. The Shadowlands expansion introduces the Xan—a race of Precursors who created humanity, all but destroyed in a terrible cataclysm eons ago. One of the surviving factions (the Redeemed) launched great space-arks that were meant to seed life across the galaxy, but the other faction (the Unredeemed) destroyed every ark except the one that landed on Earth. Alien Invasion wiped that out by revealing the Kyr'Ozch aliens, who invaded Rubi-Ka due to actions taken by the players in the Shadowlands expansion—except a quest added to the game after Alien Invasion's release revealed that the Kyr'Ozch were created and are being controlled by a god-like being as old as the Xan who survived the cataclysm.
 * ...And then subverted back to being just plain old aliens when it's explained that like humans, they're children of the Xan...but have evolved so differently then compared to humans that they might as well be hyperintelligent shades of blue for all that they're similar to mankind.
 * In the Killzone games, it's 2360, humans have colonized dozens of worlds, but haven't found any alien lifeforms whatsoever. The conflict itself is between humans and altered humans.
 * This trope is played to the letter (to great effect) in Starlancer, which is ostensibly a retelling of World War II In Space.
 * And then averted in Freelancer, the spiritual sequel.
 * Xenosaga: despite a significant portion of the galaxy being colonized, there are no real aliens. The apparently alien Gnosis are actually altered humans and supernatural beings such as U-DO and chaos were created or at least given their present form by humanity's collective will.
 * Imperium Nova has this by default, but some players choose to role-play their houses as aliens and, in one case, a game administrator orchestrated an alien invasion of a galaxy.
 * In Infinity the Quest For Earth, there are several hundred worlds grouped in clusters in several parts of the galaxy, and no other races have appeared; according to the developers, this is mostly to avoid what they think is the overused idea of a plethora of races.
 * In Dead Space, humanity has no qualms about cracking apart planets (and thereby destroying entire solar systems) for resources, since there are no aliens around to protest. At least until the game begins,
 * Elite 2: Frontier has flying saucers in secret military bases, but the game play plays this trope perfectly straight because the only inhabitants of the whole galaxy are humans. However, the sequel (Frontier: First Encounters)) averts this and reintroduces the Thargoids (they first appeared in the original, elite, as a random encounter), an actual alien race which inhabits the systems of Polaris, Pleione and Miackce. The player's experiences with the Thargoids are the "first encounters" referred in the subtitle.
 * In some Super Robot Wars timelines, all the Human Aliens are actually descendants of a lost civilization from Earth. Even the Einsts have some connection to Earth, though they mostly hang out in a parallel universe.
 * In the MMO EVE Online there are five distinct sentient races (only four are playable) and several non-playable races within the game, however they are all descendants of Human beings who traveled through a wormhole in to the space of New Eden 25,000 years before. Even newer races introduced such as the Sleepers are believed to be of human origin. The only non-human life are flora and fauna.
 * "Halo" For the first 200 or so years of human space colonization, humans had no contact when aliens. And when they do It Got Worse
 * In Total Annihilation, the Galaxy has already been thoroughly explored and colonized by humanity thousands of years ago, and no hints of intelligent alien life are mentioned in the backstory (though there are alien plants on some of the planets battles are fought on). Both Core and Arm factions are derived from Earth human stock.
 * Outpost 2 is also an Absent Aliens setting, with only humans that are trying to survive after earth is rendered unlivable by meteorites. The conflict comes between two factions fighting over the scant resources and trying to win an evacuation race from New Terra being destroyed by terraforming drones made by one of the factions.
 * Section 8 (video game): Prejudice presents a plausible explanation for the complete absence of any alien lifeforms in the galaxy, despite humanity having spread out and colonized a huge chunk of it.

Webcomics
"Look around! If it's this easy to live forever, where are all the grown-ups?"
 * In A Miracle of Science, the fact that there are no surviving aliens is a key factor in why Mars came back in contact with the rest of humanity.
 * Far Out There establishes this right at the start, though there are plenty of genetically manipulated humans who might as well be aliens.
 * Pictures for Sad Children does this while lampooning Star Trek: the captain's greatest feat was discovering alien algae 40 years prior.
 * As of yet, Crimson Dark.
 * Schlock Mercenary makes reference to Fermi Paradox - there are many aliens, but almost all are relatively young civilizations. Except F'Sherl-Ganni who became behind-the-scene manipulator and Bradicor who nearly wiped out themselves and became an immortal relict before they met others, but they aren't too old, compared to Oafa, who gone extinct. As Petey said:

Web Original

 * Associated Space, at least so far.
 * Nexus Gate

Western Animation

 * The BattleTech animated series has alien life but no intelligent nonhuman beings. See the Tabletop Game entry for more details.