"There is little left for us. Little time. But much irony: we did discover that they are not invulnerable. The Destroyers that darkened our skies like a plague can be harmed... we have the knowledge, but not the means. And so this is our legacy: in subspace they cannot use their shields... and into subspace they can be tracked."
7 Seeds takes place After the End and reveals that when scientists predicted that meteorites were going to crash on earth and most likely wipe out humanity, the government did several methods and measures in hopes of minimizing the damage and one of them, which was said to be the most outrageous and idealistic method, was to select five groups of seven people and one guide each (the "7 Seeds Project") and cryogenically preserve them until earth was deemed inhabitable again. The manga shows the good and bad sides of doing this.
Flame of Recca: Recca was born in the Warring States Era, but flung into the future (that is, our present) by a forbidden spell, to escape the annihilation of his ninja-clan at the hands of Oda Nobunaga. Unfortunately, The RivalPsycho for Hire hitched a ride...
Scrapped Princess: the eponymous character, Pacifica Casull, was genetically designed to resist the will of automated defense mechanisms that had taken over the world in an interstellar war thousands of years earlier, however it was done in such a way that the necessary genes for her creation wouldn't come together until long after humanity had ever forgotten that they were in an interstellar war.
Gall Force: With both sides about to wipe each other out, our heroines manage to encode a chip with a message for the future, so something of their civilization will survive. The epilogue shows astronauts from the present cycle (us) recovering the space probe. It doesn't end well.
GaoGaiGar: The leader of the Green Planet sends his son, and a giant mechanical lion, to Earth to escape Zonderization, along with technological records of the weapons used to fight them inside the lion.
Spriggan: An advanced ancient civilization, on the eve of its destruction, leaves behind a message plate with the inscription "Protect our legacy from evil forces." The Arkham foundation and its agents, known as spriggans (or Strikers, in English) are supposed to uncover and seal away all advanced artifacts of said civilization to prevent the destruction of our own.
The premise of Sailor Moon with the dying Queen sending the senshi's souls forward from the utopian moon kingdom as it collapses, in order to reincarnate in the modern era so they can defeat the dark kingdom as it reawakens
The Gunmen and spiral tech in Tengen Toppa Gurren Lagann were all initially designed to fight the Anti-Spirals, and still work in that function. After a crushing defeat from the Anti-Spirals, the Gunmen were retooled to suppressing spiral life so the Anti-Spirals would not indiscriminately wipe them out. When the Anti-Spirals came knocking after Lordgenome's defeat, they were restored to their original function to save humanity once again.
Neon Genesis Evangelion: Evangelion Unit-01. So long as a single human soul exists within it, it will stand as eternal proof that Humanity existed, even when the Sun, the Moon, and the Earth are all long gone. That's rather hopeful for a series well known for its terrifying imagery.
One Justice League comic featured a colony of sentient bacteria in a child's brain. The shrunk League tried to warn them not to harm their host but they weren't believed by most. Before the colony was lanced with a surgical laser one conjugating pair of scientists sent their offspring in a capsule to the liver.
The act of driving off Gah Lak Tus actually takes a few things — Vision's intervention and psychic contact by the X-Men among them — but an interesting variation of this trope occurs at the end of the storyline. After Reed Richards's superweapon (a dimensional gateway that links to another universe's big bang, directing the energy as a weapon) finally drives off the Devourer of Worlds, Nick Fury sends Vision off, back on its journey. Except this time, rather than telling sapient species to pray to whatever god they believe in, it will be carrying schematics...
And a message, directly to the citizens of the universe, from resident badass Nick Fury: Human Beings can blow the crap out of ANYTHING.
The 616-Galactus does this when the Silver Surfer is his herald, as he knows that Surfer will warn people to escape. So long as he gets to feed, it doesn't matter to him whether there's anyone on the planet. When the Surfer actually tries to stop him...
In Empowered, Mind@#$%'s video gives Emp an idea on how to take down a seemingly unstoppable bad guy.
Also the Xerbians of the colony ship Antra. Where the sister ship Xabra was shot down immediately and the Xenia escaped to establish a colony, the Antra went straight to Earth to warn us about the Evronians, so that our primitive but more militaristic race will be able to fight back and maybe stop them. Too bad they were caught between the Evronian fleet that had invaded Xerba and the one preparing the invasion of Earth...
Crisis on Infinite Earths opens with a homage to the Superman origin story. As a wall of antimatter sweeps across Earth-3, Earth-3's sole superhero, Alexander Luthor, and his wife, Lois Lane-Luthor, place their infant son Alexander, Jr., into an experimental device that will send him across the dimensional barriers to the relative safety of Earth-1.
Lex Jr. is an interesting example, because within that story, he is an enormous help to the safety of the multiverse. However, by the time of the next crisis, he has performed a Face-Heel Turn and proves that Light Is Not Good.
Humanity did this twice in Diaries of a Madman, first when they tried to save themselves from Discord, and again when they created the species that now populate Earth when that failed.
Films — Animated
Both Megamind and his arch-nemesis Metro Man have the same origin story up to the point of them crash-landing on Earth. Their planets were about to be sucked into a black hole, so their parents sent their infants away.
Films — Live-Action
The eponymous hero of Willow does this to The Chosen One in the climax, sending her somewhere "where evil cannot touch her!" Not really. He just used sleight of hand to hide the baby and make Bavmorda think she was gone. It worked so well even the good witch fell for it.
Alien. The unnamed Pilot of the alien spacecraft left a warning signal; unfortunately it only succeeds in attracting people to the derelict.
In Iron Man 2, limited by the technology of his time, Howard Stark leaves a film recording and a model of the first Stark Expo so that Tony can synthesise the element needed to perfect the Arc Reactor.
Mission to Mars reveals that the Martians did this after Mars was struck by an asteroid turning it into the lifeless rock we know. Slightly subverted in that some members of their species survived and fled to another galaxy (because that's what you do when your home is destroyed by a hurricane - you move to another country). This "light" is the primordian seed that kick-started life on Earth, eventually resulting in humans, all so we can get to Mars and find out the truth.
This happens to Luke, Leia, Yoda, Obi-Wan, and the whole proto-rebellion at the end of Revenge of the Sith. Obi-wan and Yoda go into exile, the twins are sent to adoptive families in secret, and the rebellious senators vote FOR the newly christened Emperor.
In the 1997 film of Prince Valiant, when Thule was conquered by the Vikings, some survivors managed to escape with the baby prince and dropped him off at an orphanage in England, confident that he would one day grow up and retake the throne.
In Serenity the crew find an Apocalyptic Log on the seemingly dead planet Miranda that explains how the Alliance accidentally wiped out the population and the survivors became the Reavers, in hopes that someone could prevent them from trying it again. It starts with this line:
"I won't live to report this, but someone has to know."
A species doomed to extinction by a black hole crashing through their starsystem in Greg Egan's Incandescence takes a radical approach to Fling A Light Into The Future: they engineer a de-novo descendant species and culture able to live within chunks of rock orbiting inside the accretion disk.
Similarly in Olaf Stapledon's classic Last and First Men, the Last Men, realizing that changes in solar radiation will destroy all life in the solar system, launch a gigantic project to fire the "basic germs of life" into interstellar space, so that one day they will reach a planet and the cycle of life will begin anew.
Also, Arthur C. Clarke's The Light of Other Days had a similar plot point - an intelligent species evolved on Earth several billion years ago, but was about to be destroyed by an asteroid impact that they could see coming but couldn't stop, so they filled the earth with bacteria so that at least the basic building blocks of life would survive.
This requires a little bit more clarification. There are actually three timelines involved. The original timeline sent a device to convince Christopher Columbus to travel to the New World instead of leading a final, victorious crusade to capture Jerusalem for Christianity creating the second timeline. This second timeline (which is supposed to be our own but Twenty Minutes into the Future) sends actual people back in order to directly influence events to produce the third when it becomes clear the planet will shortly be unable to sustain any human life (the rain forests are GONE and not coming back while what farmable land is left is about to give out for good). The people of the 15th century wouldn't be able to understand what was going on, so the time travellers had their timeline's history etched directly onto their skulls so that future archaeologists could find it and know the sacrifices that they had made.
What was etched on the metal plates in the skulls were directions to discovering the archived knowledge from the second timeline. Namely, a frequency to be used to locate the data. They were discovered in the third timeline's 1955 and used this knowledge to honor Kemal's Heroic Sacrifice.
Also, in case you're wondering why the original timeline had to be changed was because without European interference, the much more progressive but still bloodthirsty Tlaxcalans manage to take over the waning Aztec Empire and spread through Mesoamerica and beyond. When the Portuguese eventually discover America, they are captured and forced to teach the Tlaxcalans how to make guns and oceangoing ships. The empire then sends a vast army across the Atlantic to the unprepared Europe. The result is all of humanity dominated by a culture whose bloodthirsty god demands regular sacrifices in the thousands.
One person from the second time-line refers to the time-travel project as the only chance to make a better a world for "our children", when someone starts to correct him on how the time-travel won't work like that, he explains that he was referring to all the people of the third time-line, not his flesh and blood offspring.
In a Stephen Baxter's short story "The Quagma Datum," a species in the very early universe creates a lithium 7 nova as a signal to the later universe that they were there.
And in Manifold: Space, a coalition of aliens are working on a mammoth solar sail designed to prevent two neutron stars from colliding and sterilizing the galaxy... except there's another collision—too late to prevent—that's going to occur first, killing the current generation. And the sail they're working on is leftover from a previous cycle.
This was the avowed intent of Winston's diary in 1984, at least at one point. He knew it wouldn't work, and mostly did it for catharsis. That didn't work either.
Alastair ReynoldsRevelation Space series has this, in the first book Sun Stealer warns Ana Khouri and by extension the humans of Resurgam about the Inhibitors, though that wasn't the reason why it was created. In Redemption Ark, it turns out that the Conjoiners had discovered a way to receive messages from a parallel future and had been getting ready for the Inhibitors all along.
Also in Clarke's second A Time Odyssey book, Sunstorm, where a dying alien civilization (only few peoples left) and 2 Human-made AI decide to use their last strength to send the third AI back to Earth to give humans more information on the Firstborn.
Inverted in the Fighting Fantasy book Black Vein Prophecy: Bezenvial, tyrannical king of the Isles of the Dawn, faces death within a few hours and so has his sons entombed in order that his evil legacy can live on. One son becomes the Big Bad of the story - the other is the player, who may or may not succeed in overcoming the legacy of the black blood flowing within his veins.
Essentially the reason for the eponymous Foundation in Isaac Asimov's series of that name, both in actual fact and the cover story... except, instead of flinging a light of knowledge and possibility into the future for others, it's for humanity itself.
Richard is revealed to be that in the later books of the Sword of Truth series.
Prophecy in general, thought YMMV on that one. In fact, in-universe YMMV.
Several of the tests that Richard has to face. Justified, since the Wizards from the Great War knew that Subtractive Magic was locked away from future generations in the Temple of the Winds before War Wizards started to die out.
There was a short story called Last Contact where the Big Rip happens much earlier than expected, and there's a throwaway line about how they're discovering new alien stars daily, because those aliens are doing very noisy artificial things (like throwing a huge pile of exotic atoms into their sun) simply as a "The universe is ending, but I'm here!" Or as one of the human characters put it "they were saying goodbye". At the end, there was a device which had been designed by humans to record data about the Rip, in the hope that some of it might survive and might be found by and be of use to a hypothetical race in the next universe.
This is the direct origin story of one of the Sufficiently Advanced Aliens of Perry Rhodan. A highly advanced species faced with a slow decline into extinction embarks on a long-term project to send all of their accumulated knowledge out into the universe in a self-sustaining "Prior Wave". It takes long years and much difficulty until the wave is finally sent, and it travels through the universe for rather longer, touching the ancestors of at least one known civilization along the way...until it gets absorbed, purely by chance, by a cloud of cosmic dust that is going to collapse and form a solar system. Fast forward to the actual formation of the planets, and one of them in the new star's habitable zone is featuring a super-intelligent crystal shell englobing much of it (and eventually its atmosphere) — the future Empress of Therm. (A poignant scene shows how the last survivors of an expedition launched by the Empress much later, after intelligent organic life has finally evolved on her world and she's gone about building the actual empire she takes her name from, discover that planet of origin...a dead world with no signs of the original civilization left at all. Even the ruins have long since crumbled into dust.)
A version of this trope, less dire when it was enacted, happened in the Star Wars Expanded Universe. Alderaan's pacifism is mentioned to be a relatively new development. When it became global, some of their weaponry was auctioned off, some was melted down and repurposed... and two warships were set aside, computer-controlled and kept in local space. The Rebellion found one not long after the world was destroyed. In the X-Wing Series, one came to Rogue Squadron's rescue.
It was actually four ships: one ship dedicated to carrying the weaponry, and three more automated, to act as its escorts. The armory-ship was found by the Rebels, and one of the escorts which got lost eventually helped the Rogues.
In Martha Wells' City of Bones, the Krismen (humanoid marsupials resistant to poison, drought, and desert sun) were created so that at least something mostly human would be able to survive in the wasteland consuming the known world. (And then it turned out that normal humans could live on the fringes of it just fine, so now the Krismen are a hated underclass whenever they leave the desert to do business in the cities.)
The Star Trek novel Eyes of the Beholders featured the Enterprise encountering an art museum built by a now-extinct race for this purpose.
The Book of Mormon purports to be collection of prophetic writings abridged by Mormon, one of the last of a persecuted line of Christians in the ancient Americas. Mormon wrote this abridgement on golden plates that would be hidden in a hillside for centuries, in hopes that the fall of his people would serve as a warning to future inhabitants of the Americas.
Entropy by Andrew Galvan features several occurrences of this. First, the numerous 'ambassadors' who were sent out in cryogenic suspension pods on the off chance one of them might meet a Sufficiently Advanced Alien in time to save humanity from a plague. There was also the incident where a scientist launched a pod containing an artificial intelligence and much of humanity's remaining knowledge. That artificial intelligence would be the first in a line of AIs until Noah, the hovering ball of energy we come to know and distrust in the present, at the end of the Universe. By the end of the book, he has proven that even super-advanced A.I. Is a Crapshoot.
Apollo's Grove is the story of the last Oracle of Delphi, who knows she is the last Oracle and whose mentor gave her the task of writing a chronicle of her temple and her faith so that people in the future would know both existed. She succeeds.
The Wheel of Time has many examples, considering that in the backstory civilization collapsed after the war against the Dark One and the tainting of saidin. This includes both powerful artifacts (such as Callandor) and prophecies to warn people of what is to come.
Karl Schroeder's Permanence involves this, as ancient aliens realise that species eventually evolve away from intelligence, and that the only thing that lasts are the ecological niches that give rise to intelligence.
In David Brin's Existence it turns out that the alien personalities in the Artifact are all from extinct species, and they want humans to join them before we become extinct. While the other Artifact that is calling them "liars" is from one species that decided the expense of building and launching millions of Artifacts is what killed off all the others, and they're trying to convince the few extant species not to do it.
As a pandemic rages in Idlewild, available resources are split between desperate treatment and the Gedaechtnis project, which genetically engineers children who will be immune to the disease and builds life-support systems to raise them to adulthood sans caretakers.
Motie civilisation is stuck in a cycle of this in The Mote In Gods Eye. Since Moties must reproduce regularly or die, their population inevitably increases until overpopulation results in the collapse of their civilisation, usually through war over resources. At some point in the past, they came up with the idea of building museums storing as much of their science and technology as possible, so that they will be able to rebuild faster after the collapses and hopefully have time to find a way to break the cycle before the next one occurs.
An unintentional example in The History of the Galaxy. Millions of years ago, our corner of the galaxy underwent a devastating cataclysm in the form of a Horde of Alien Locusts called Forerunners moving through space, attracted to starlight, eating all matter in their path. Three of the ancient races in the region manage to save themselves by hiding inside a globular star cluster and using powerful gravity generators to cloak it from outside view (the gravity generators kept light from escaping the cluster; thus the Forerunners couldn't see it). A race of Fish People called Delphons chose to stay and fight. Their only means of fighting the Forerunners was their own stars, which they used as beacons to attract the swarm and then set off a nova reaction. By the time the swarm was destroyed, the Delphons were extinct. Three million years later, a human archaeological team finds a group of frozen Delphons and several inactive Forerunners. A Corrupt Corporate Executive downloads the memories of one of the dead Delphons and puts them into the brain of a human soldier. At the same time, he experiments with the Forerunners, not realizing the danger they represent. In the end, it's the memories of the dead Delphon that allow the soldier to figure out a way to stop the Forerunners (a handful of them rip apart a human fleet just before).
One of the memories experienced by the soldier has him looking at a hominid, implying that the Delphons had a colony on Earth and pulled a species-wide Heroic Sacrifice to allow younger races to evolve.
In Babylon 5, this is revealed to be the fate of Babylon 4. Was set up to be this particular trope, but turns into "Fling a Light into the Past", or almost a Kyle Reese sort of thing.
Though they weren't actually going extinct, some alien dissidents preserved a collection of their race's greatest artistic masterpieces when their government declared art to be an illegal waste of resources. This precious collection was later salvaged by the Excalibur's crew on Crusade.
In the prequel movie In the Beginning Mankind does this: when Earth is about to be hit by the unstoppable Minbari, hundreds of civilians are evacuated as Earthforce and any ship capable of fighting try and buy time fighting the Minbari, so that Mankind will still survive.
The tearjerkingly brilliant "The Inner Light", an episode of Star Trek: The Next Generation commonly seen as one of the best, tells the story of an alien race doomed by instability in their sun who send out a space probe that finds Picard and forces him to hallucinate living a lifetime among their final generations before the end, and thus ensures that their species will at least be remembered. It affected Picard and no other crew member. The life he lived involved getting married, having a family, and other things he's never made time for - taking it from a disturbing experience to something he sees as a gift.
The episode "The Chase" reveals that all humanoid life is this—a Precursor species that inhabited the Milky Way eons before life anywhere else was more complex than bacteria seeded planets all over the galaxy with DNA so that evolution there would result in people who resembled them after their eventual extinction. They left a message coded in DNA to explain all this. (This is less well-regarded by fans, since evolution does not work like that and it comes off as a justification for the Rubber-Forehead Aliens.)
Subverted in Star Trek: Voyager 's "Course: Oblivion", in which the Silver Blood duplicate of Voyager 's crew create a log capsule that will survive after them, and their attempt to launch it fails, destroying it. The ship disintegrates just beyond the real Voyager's sensor range.
The final message from a never-seen culture to "Beware The Destroyers" is the only reason Stargate SG-1 lasted more than a season.
Also an Alternate Universe SGC in "There But For the Grace of God" were the ones who received the message from an unknown culture that was about to be wiped out by the Goa'uld. It gave them the gate coordinates from which the Goa'uld launched their attack. Unfortunately this SGC never learned how to speak Goa'uld and the warning went untranslated until a quantum mirror landed the prime universe's Daniel Jackson in that one. At which point it was too late for that Earth because the Goa'uld were already there. Luckily, Daniel was able to return to his own universe with the gate coordinates, and SG-1 subsequently defied orders to save the planet from Apophis's invasion.
Then they did it again with the Asgard.
And the Ashenn storyline involved flinging a light into the past. They like this one.
In Battlestar Galactica, the Final Five Cylons arranged to be reborn following the destruction of the Earth by Paleo-Centurions. Using a sublight ship, they headed to the Twelve Colonies of Kobol to attempt to warn the human tribes of similar dangers. In vain.
The Andromeda Ascendant on Gene Roddenberry's Andromeda, except that it was thrown into the future by accident.
Buck Rogers in the 25th Century. Although it was completely an accident. And the fact that although the civilization he knew was destroyed, a brand new society took its place.
In "The Music of the Spheres", the world is bombarded by alien broadcasts that anyone under the age of 21 or so believe to be the most beautiful music they've ever heard. When the broadcasts prove addictive and cause those who listen to them to mutate, the world governments declare martial law, until scientists succeed in decoding the message. The signals originated on a world whose sun had turned ultraviolet 40 years ago. The signal warned that Earth's sun was about to undergo a similar change, and that the broadcasts would genetically alter those who heard them into a new golden-skinned form that could survive under the new sun. Fortunately, it had a rare good ending with no twist involved: the powers that be actually realize the importance of letting that music play, specifically rebroadcast it across the world, including using mobile vehicles to get the sound out to third world countries and to the non-human life on the planet, and in the end, it's insinuated humanity will be just fine. Even those who are too old/decide not to mutate will live... indoors and underground.
In "Origin Of Species," a group of students is brought to the future where they find that humanity, in the interim, got heavily into genetic manipulation, basically dooming the human race. When they realize the small group of them isn't enough to sustain humanity for more than a generation or two, they later find enough babies of different genetic mixes, in the ship that brought them to the future, to give the human race a second chance.
The basis of the plot in Power Rangers Wild Force. The Animarians were losing a war against the Orgs. Both sides were mostly destroyed the Orgs leaving behind some Sealed Evil in a Can, and the Animarians leaving behind a Floating Continent, a princess in stasis, and a few giant robot animals scattered around.
Jikuu Senshi Spielban's heroes serve this purpose, as they were sent to Earth which turns out to be what their planet was in the past after their civilization was attacked.
In Supernatural Sam and Dean have to go to the past and retrieve the ashes of a Phoenix to destroy Eve. They succeed in killing the Phoenix but can't get to the ashes in time due to their limited time frame. Samuel Colt, yes that Samuel Colt, sends the ashes to them via Western Union with instructions to wait like 100 years so that they get them in the present. It's not technically the future but it was Samuel Colt's future.
Inverted in a profoundly dark and disturbing way by the Illithidrace in Dungeons & Dragons (at least before4th Edition). The Mind Flayers were - or will be - the overlords of the multiverse at the literal end of time, when most if not all the stars have burnt out. But after facing defeat at the hands of a trans-planar rebellion (not that there's much to fight over at this point), the Illithids sacrificed unbelievable numbers of their Elder Brains to create a psionic maelstrom that sent the surviving members of their race into the distant past - that is, shortly before the D&D setting. This way they can get a head start on forging their empire while avoiding that pesky slave uprising altogether. It also explains their tremendous egos; after all, they knowtheir victory is inevitable.
One more disturbing note about the Illithids - it's possible for characters to take feats representing having monstrous non-human ancestors, like a bit of dragon blood in your family tree or something. If you apply them to the Illithids, it doesn't mean you have an inhuman ancestor, it means that the squid-faced, brain-eating monsters with the parasitoidic life cycle are your descendants.
Dead Space 3: Dr Serrano's 200 year old logs are crucial for Isaac's attempt to stop Convergence. Serrano explicitly made them so that someone else might finish what he couldn't.
Sid Meiers Alpha Centauri treats the UNS Unity as this. The novelization Journey to Centauri makes that chillingly clear; right after the future faction leaders realize they were a light flung into the future, a short list of Earth's major networks and facilities are listed as "offline" or in various states of error.
Pravin Lal: To the people of that regime…to see the Unity catapult itself into the night sky…and to think, in the pain, the poverty, the death and sickness all around, that perhaps, in forty years time...hope. For humanity.
Deidre Skye: So they fired us off, a wild firecracker into the sky, and they hoped.
A slightly more hopeful version in the Spiritual SuccessorCivilization: Beyond Earth. While Earth's ecology has sustained irreparable damage, and many natural resources are used up, Earth is not gone. In fact, two of the endings involve opening a portal to Earth from the new planet (a Purity faction uses the portal to get reinforcements from Earth to conquer the new world, while a Supremacy faction does the reverse and conquers Earth instead).
In Mass Effect, several Prothean scientists used an experimental one-way Mass Relay to travel to the Citadel and block the Reapers' primary route into the galaxy, in the hopes that it would give the next advanced species that would arise - some 50,000 years down the road - a chance at stopping the Reapers' cyclical extermination of sentient life. It's all the more tearjerking when you realize that they had departed from a hidden sanctuary world where they had been held in stasis as the galaxy burned around them, after the managing AI had switched off life support to all the other colonists to preserve their lives, as they were classed "critical personnel".
Also, the beacon from the beginning of the game served a similar purpose, though it was not intentional.
It's not a coincidence "Vigil's Theme" is the menu music for Mass Effect.
In Mass Effect 3, with the Reapers invading and galactic extinction a possibility, Liara makes a point of documenting the struggle and leaving vital information behind for future races in case they don't make it.
Also from ME3, we have the Crucible, a superweapon designed to fight the Reapers by one cycle, and left for the next to find. That cycle found it, but was unable to complete it, so they documented what design changes they could, and hid it for the next generation, passing it on and on, through the ages, always hoping that the next might be able to finish their work. Every reiteration of the Crucible brought it closer to completion, and each cycle that failed to complete it ensured that the knowledge was left for the next. It's even mentioned that the Crucible was extremely simple in design, ensuring that the next cycle would be able to translate it with the limited knowledge they would find in the ruins of the cycle that came before it.
We also have Javik, the last Prothean. A soldier during the last days of the Prothean Empire, whose plan was to go into cryosleep with hundreds of thousands of others, so that they could rebuild the empire after the Reapers left for dark space again. Unfortunately, several Protheans on the colony end up indoctrinated and sabotage the defenses. When Javik is about to be frozen, the facility's VI called Victory informs him that there's not enough power for all the occupied pods to last long enough, and what's worse: automated unfreeze is no longer an option due to damage. Following its programming, Victory shuts off all the pods but Javik's despite the latter's protests. Victory tells Javik to tell future races of the Protheans. However, Javik has other plans - he will be an avatar of vengeance against the Reapers.
Invoked by Garrus after recruting Javik, who half-seriously suggests that if they ever come close to losing the War, they should take a leaf out of the Prothean's book and put Shepard on ice, ready for Round Two in 50,000 years.
Additionally, there's the VI Vendetta left behind on Thessia by the Protheans to aid the asari in becoming the dominant species in the next cycle.
In the "Refusal" hidden ending added by the DLC Shepard refuses all three of the Catalyst's solutions. The next thing we see is a hologram of Liara in a hidden underground chamber telling someone not to make the same mistakes they did, presumably one of the many time capsules she seeded across the galaxy for the next Cycle. It's implied that this time, they succeeded in destroying the Reapers.
Halo. The namesake of the series is simultaneously a warning and the threat. Also, humans are the Reclaimers chosen by the Forerunners to take up their cultural legacy, called the Mantle.
It's the whole premise of Halo: Reach, as you already know that the entire planet will be destroyed with barely any survivors, but that one ship makes it out with the coordinates to reach the first Halo. The last parts of the game are all about retrieving the data from an ancient ruin before it's overrun by enemies and take it to the last remaining warship in the hope that it will find something at the coordinates to help save humanity from total extinction. At that points it seems as if you're the last handful of humans still alive on the planet and when the Autumn takes off, you stay behind to cover their escape, watching it disappear into the sky. And then you're completely alone in the ruins, with an infinite wave of enemies crashing down on you.
The Framing Story of the Assassin's Creed series is that of a modern day Mega Corp. recruiting people to relive their Genetic Memory via a device called the Animus in order to locate powerful artifacts left behind by Those Who Came Before with the objective of using them to Take Over the World. Well, it turns out that the ancient species in question knew this would happen and left behind messages designed to be seen by the people communing with their ancestors via the Animus. This is all being done in order to avert a recurrence of the same catastrophe that destroyed their First Civilization. The Assassins themselves worked to conceal the artifacts of the First Civilization in order to prevent them from being recovered and used by the Templars; it is therefore up to their modern-day descendants to recover and use said artifacts for their intended purpose. Horrifyingly subverted in the third game since one of these precursors, Juno, is still alive as a Sealed Evil in a Can. She hijacked the First Civilization's plan so that she would ultimately be free to conquer humanity again.
Backstory of the Shivans in City of Heroes. An alien planet destroyed by Shiva sent a probe to Earth to warn it that it was the next target. Humanity found this, deciphered the language, found they had only a little while before Shiva would destroy them, and blew Shiva up. Unfortunately, the fragments landed on an island a bit close to home, and are trying to reform themselves.
In Starcraft II, the final mission of Zeratul's mini-campaign takes place in a possible future where the remaining survivors of the Protoss fight a doomed last battle against the near-omnipotent Dark Voice and his army of Zerg and Hybrids. The bonus objective involves protecting the Archives long enough for the Preservers to seal away the history and knowledge of the Protoss, so that someday a future race might use it against the Hybrids. Funnily enough, though, it's Jim Raynor who receives the benefits of that history and knowledge, so it's more like Flinging a Light Into the Past.
Dr. Light created Mega Man X in hopes that he would help create a world of peace. In a way, he did, but it took many hundreds of years, and Dr. Wily's last creation is just as responsible as Light's.
In the Flash game Cellcraft, a race of advanced platypus-like people discover that an inescapable cataclysm will wipe out all life on their planet. With no means to escape their eventual destruction, they breed microbes (the premise of the game) tough enough to survive even the most hostile conditions that are still capable of supporting life and send them to another planet — that planet being Earth. This is apparently the origin of platypi on Earth and handily explains why they are so strange — they are aliens.
The Vault program in the Fallout universe. At least the handful of control vaults were, the ones given a Garden of Eden Creation Kit to help rebuild a post-nuclear wasteland. All the other Vaults? Insanely twisted social experiments.
In Fallout: New Vegas: Dead Money, the Sierra Madre Casino is still broadcasting its Grand Opening message 200 years after the bombs fell and the town was covered with a lethal smog and overrun with mutants.
In Homeworld the ancient Hiigaran Exiles, realizing they were being forced to leave their city about to be buried in sand and lose their technology, left into it the Guidestone to tell their descendants the way for their ancestral Homeworld and an hyperspace module to reach it.
Unfortunately, they neglected to mention the Binding Ancient Treaty preventing them or their descendants from using said module.
Inverted with SaGa 3. Three children as sent from the Future into the Present in hopes of stopping the world from being completely flooded.
Serious Sam of his namesake series is this (though inverted as the light is flung from the future,) going back in time to stop Mental before he can take over the Earth. Prequel game Serious Sam 3 makes this even more clear, as Sam is literally the last surviving present-day human after Mental destroys the Earth by crashing the Moon into it.
Avencast: Rise of the Mage had one woman of the Kyranian empire send her children away from the civilization's final battle, though she intended for them to live rather than finish the fight later.
Starlancer and Freelancer are set around this trope. The former is set during the fight between two huge forces in our solar system; The Coalition and The Alliance. The latter is set 800 years later and in the backstory it details how The Alliance, faced with defeat, put thousands of their people into stasis in five huge sleeper ships and then shipped them off to the Sirius system to build a new cooperative life away from the war. Predictably this utopian ideal doesn't come to pass, with four major competing factions (one from each of four sleeper ships) being set up and the fifth sleeper ship ending up as a bunch of pirates.
The original (and, according to Word of God, still canonical) intro also shows the destruction of the Solar System by the Nomads shortly after the departure of the Alliance sleeper ships. A single ship survives the resulting nova. It's not specified if it's an Alliance or a Coalition ship, but the captain chooses to follow the colonists to warn them of the Nomads. The phrase "we will never forget" takes on a new meaning here.
The player, in Final Fantasy XIV. After a climactic battle with The Empire, Bahamut is summoned and starts destroying everything. A powerful wizard sends the heroes of the battle five years into the future, moments before the battlefield is obliterated by Mega Flare.
In Homestuck: Rose rips her incomplete walkthrough out of the internet and seals it in the Furthest Ring so that other SBURB players can read it. In an inversion, the person to read it turns out to be Kanaya, in the session directly responsible for Rose's universe.
Skaia uses the defense portals to save itself from meteors from The Reckoning to the home planet of the players, scattered along its timeline… which contain many resources required to start the session, including the baby players and ancestors themselves.
Nedroid: Beartato's parents put him in a rocket before their planet was destroyed. Reginald, in a similar rocket, was sent up because his father had stuff to do.
SCP-1281 with it's last message from a civilization long gone.
Subverted and parodied in Sealab 2021, where the crew leave a capsule for future generations to find. It contains toxic gas and a note reading "Eat it, future bastards!"
An inversion of this was the premise of Samurai Jack. Aku, the Big Bad, was not strong enough to defeat the eponymous hero, so instead flings him into the future. Jack arrives in an era where Aku is the unquestioned ruler.
The origin story plays it straight. When Aku attacked Jack's homeland, Jack was safely evacuated and spent the next 20 years traveling the world and training. He returned too late to save his people, but could have avenged them if the series had not been cut short.
He may still get his chance if The Movie works out.
When the Iacon Hall of Records was sieged during the last days of the war on Cybertron, Alpha Trion of Transformers Prime had the hall's powerful relics and weapons sent to Earth because he had forseen that Optimus Prime would eventually come to engage the Decepticons there during one of the war's most important chapters.
In The Venture Bros. episode "Twenty Years To Midnight", Jonas Sr. receives a message that the fate of the universe depends on him building a machine and getting it to Times Square in 20 years. He dies before then but leaves a message to his son with all the details and where he hid the pieces. It's one of the few times Rusty actually does something good successfully (despite several obstacles, obviously).
According to the show, the longest-lasting element of human civilization will be probes sent into deep space, and the instruments left on the moon, where the lack of atmosphere (and thus erosion) will preserve them much longer than anywhere on Earth. Asteroid and micrometeorite impacts will eventually destroy the moon instruments, while the probes will suffer a similar fate from interstellar dust, though at an even slower rate.
Several cases during World War II. Most of them, with the exception of the first example are more of hoping that their allies will rescue them in the future, rather than just sending the light off to help others.
Several inmates at Nazi concentration camps wrote and buried diaries to let the world know what happened.
The history and life of the Warsaw Ghetto was extensively documented by Jewish scholars and buried. Most but not all of the document caches have been recovered.
...and even if, which I do not for a moment believe, this Island or a large part of it were subjugated and starving, then our Empire beyond the seas, armed and guarded by the British Fleet, would carry on the struggle, until, in God's good time, the New World, with all its power and might, steps forth to the rescue and the liberation of the Old.
As Poland fell, they sent off to the UK their work on breaking the German codes. This has been portrayed as a dying man flinging his sword to his ally, so they can continue the fight.
Several of The Long Now Foundation's projects are about this. They include a clock to run for ten millenia and an effort to preserve languages that are likely to become extinct.
Some high schools have buried time capsules, where they get a container, fill it with stuff from their year and bury it. Decades later, at a school reunion or something, they dig it up and see what everyone put in there to reminisce about their teen years.
Take up our quarrel with the foe: / To you from failing hands we throw / The torch; be yours to hold it high.
A total of five space probes have been sent out, or are on their way out, of the solar system (Pioneers 10 and 11, Voyagers 1 and 2, and New Horizons). On them contains information about both the location in space, as well as when, they originate from. A number of scientists think that they may one day be picked up by some other intelligence and will tell them we were here, once note Although, others hypothesize that we may end up recovering them in the future as museum pieces to early space exploration.
On a smaller scale, this is the purpose of reproduction. Every living organism eventually dies. Its genetic material and heritage is carried by its offspring.
This is (part of) the idea behing protected archives like the Barbarastollen or "Zentraler Bergungsort der Bundesrepublik" (central retrieval site of the federal republic of Germany). The storage location is covered by more than 200 meters of granite.
Another small-scale example: One reason pilots (and especially test pilots of experimental aircraft) are trained to deliver all information in a Danger Deadpan is so that they can give a clear picture of what's going on with their craft even when disaster strikes, as it might save the lives of future pilots, crew, and passengers by allowing others to find and fix the faults that caused the accident.