The Multiversal Timeline

This is a full timeline comprised of all major events in interstellar pop-culture. From the Great Time War (Doctor Who) to the destruction of the Death Star (Star Wars). From man's first contact with extraterrestrials (Close Encounters of the Third Kind, Arrival, Contact) to the destruction of major planets (Titan A.E., Transformers, DC, The Hitchhiker's Guide to the Galaxy, Star Wars, etc.)

Before time / Before the Universe

 * Before time itself, ancient beings of darkness and light ruled the void between universes. Darkness incarnate, known as The Beast, was a being of temptation, sorrow, anger, destruction and the death of hope who has fought against the Disciples of Light. The Disciples managed to imprison The Beast in the center of a planet called Krop Tor orbiting around a black hole. The Disciples rigged the planet so that if The Beast were to escape Krop Tor, the planet will loose it's gravitational orbit with the black hole and fall into the event horizon. Over time and after the Big Bang, the legend of the Beast lived on in the universe after the death of the Disciples which inspired the beliefs in religious figures across the universe such as Lucifer or Satan and many others. (Doctor Who)
 * The Ixtl Empire forms in the universe predating our own. (The Voyage of the Space Beagle)
 * A single sentient universe exists called the First Firmament. In its loneliness, it creates the first ever beings called Aspirants. However, a group of them rebel and begin calling themselves Celestials, whose war with the Aspirants causes the Firmament to shatter and create the 2nd Cosmos, a multiverse. 4 more iterations of the multiverse come and go for an unspecified amount of time before the current cosmos, the 7th, begins via Big Bang. (Marvel)
 * The Infinite was created. (Doctor Who)
 * Six singularities occurred before existence. (Marvel)
 * Taa's civilisation is wiped out during the big bang and the only survivor of this civilisation (Galan) is reborn as Galactus in the new universe (Marvel)

Events dating back and forth through time

 * At an unknown point in history, an ancient race of aliens called Time Lords fought in a brutal war with each other at different points in history and even used time as a weapon in their battles with time loops and temporal paradoxes. This was the first Time War. A second war broke out a generation after the rule of Rassilon and lasted for 30,000 years. Instead of each other, the Time Lords fought against other races developing time travel such as the Charon who the Time Lords had destroyed. Later, the Deindum War started as an attempt to erase the Deindum from existence before they develop into a war-like race. As another war between the Time Lords and the Daleks began, a single Time Lord known only as the Doctor decided to destroy the Time Lord home planet Gallifrey in an attempt to eradicate the Dalek race during the Last Great Time War. Unfortunately, after an encounter with his future selves, his decision of committing genocide was averted and he and his future selves decided to keep Gallifrey alive by having it reside in a pocket universe trapped in time. In the midst of Gallifrey's transportation into the pocket universe, the Doctor escapes by stealing a Time Lord ship called a TARDIS and deciding to live out the lives of his future selves and travel throughout time and space. (Doctor Who)
 * In the second Time War, an unnamed species created the Reality Bomb and were later eliminated by the Time Lords. (Doctor Who)

20 billion years ago

 * The time of the Silastic Armourfiends of Striterax, who build a hyper-intelligent computer called Hactar, which is later pulverized after sabotaging what the Armorfiends intended to be the ultimate weapon. It remains operative as a cloud of interstellar dust and retains the ability to subtly influence minds and matter. (The Hitchhiker's Guide to the Galaxy)

13.7 billion years ago (the Creation of the Universe)

 * A big bang occurs (general scientific belief of the universe's creation), this big bang was caused by Azathoth. A giant amalgamation of limbs, eyes, and mouths floating through space who is a cosmic deity whose very existence caused the creation of the universe. Azathoth later brings three sons into existence: Nyarlathotep, the Nameless Mist, and the Darkness. As Azathoth continued creating and destroying many worlds in the universe, his sons created minions and devised a plan to put Azathoth in a sleep like state and put a halt to his chaos. They succeed and overtime, give existence to Outer Gods such as Cthulhu which have the same cosmic god-like status as Azathoth and his sons. These Outer Gods then bring life to various Great Old Ones who bring life to various alien lifeforms on other preexisting planets. (H. P. Lovecraft)
 * The remnants of the six singularities were forged by the Big Bang into six concentrated ingots which would become known as the Infinity Stones. (Marvel)
 * At the creation of the current universe, the Ixtl Empire is destroyed but at least one individual survives, drifting through space, feeding on the energy emanated by galaxies. (The Voyage of the Space Beagle)
 * The Weeping Angels appear in our universe. (Doctor Who)

10 billion years ago

 * Influenced by Hactar, the Krikkiters evolve and achieve spaceflight. For two thousand years, the galaxy undergoes the most devastating conflict ever recorded, the Krikkit Wars, resulting in over two "grillion" casualties. After the war ends the Krikkiters' homeworld is imprisoned in a Slo-Time envelope. (The Hitchhiker's Guide to the Galaxy)

7 billion years ago

 * The First Born evolve and achieve sapience. (Babylon 5)

4.5 billion years ago (the Beginning of the Earth)

 * A race of aliens that resemble mice creates a massive supercomputer named "Deep Thought" to calculate the answer to the ultimate question about life, the universe and everything. 7.5 million years later, Deep Thought comes up with the disappointing answer "42". But based on what Deep Thought has told them, the mice-like aliens hire the Magratheans to build them an even larger, planet-sized computer with enough processing power to come up with a satisfying question to match this answer. This new supercomputer is called Earth. (The Hitchhiker's Guide to the Galaxy)
 * As the Earth is being created, a Racnoss ship containing the Empress of Racnoss becomes buried within the center of the Earth. (Doctor Who)
 * As the Earth begins to cool down from its own creation, a Great Old One named Cthugha arrives on Earth with his legion of Fire Vampires. (August Derleth - "The House on Curwen Street")
 * The Mala'kak arrive on Earth, where they leave a single Space Jockey to consume a black liquid that melts his body into Earth's primitive oceans. The DNA left behind by the Mala'kak is deconstructed and reconstructed in Earth's oceans where life on Earth was born. (Prometheus)

4 billion years ago (the Beginning of Life on Earth)

 * A Salaxalan ship explodes on the Earth's atmosphere, with the resulting energy released resulting in the formation of the first life forms from organic molecules scattered over the planet's primordial soups. (Dirk Gently's Holistic Detective Agency)
 * In an alternate account of the above, the ship was actually a Jagaroth ship. (Doctor Who)
 * The "Ancient Humanoids" seed the primordial soups of several inhabitable planets with DNA molecules "programmed" to evolve in certain paths, thus ensuring the future rise of several humanoid species throughout the galaxy. (Star Trek)
 * The Nestene arrive on Earth to make "deposits" by burying a billion of their kind on the ley lines to soon be released billions of years later where they will begin to conquer Earth. (Doctor Who)

3 billion years ago

 * The Martian Dwarf, Setissi and Martian Glider civilizations flourish on Mars. (Doctor Omega)
 * An intelligent non-humanoid race flourishes on Venus for about three million years, before climate alterations slowly begin to mark the end of their reign. The Sou(ou)shi attempt to prey on the Venusians, but are defeated by the Doctor and physically destroyed, surviving only as a disembodied intelligence which goes dormant on primitive Earth. (Doctor Who)

2 billion years ago

 * The galaxy is ruled by the Thrintun Empire. (Known Space)

1 billion years ago

 * A race of aliens known as the Elder Things arrive on Earth in the Antarctic region and create a city within the ice. (At the Mountain of Madness - H. P. Lovecraft)
 * The hostile species known as the Hand is imprisoned in another dimension by the First Ones. (Babylon 5)
 * Formation of the Qu civilization which would war against and exterminate the Star People over a billion years later. (All Tomorrows)

Neoproterozoic Era (1 billion - 541 million years ago)

 * 780,000,000 BC: The Chirpsithra visit the Earth and make contact with the then-dominant life form of the planet, the anaerobic lifeforms. (The Draco Tavern)
 * 600,000,000 BC: The Earth and "three other solar planets" are dominated by the mysterious Flying Polyps, a race originated from "distant universes". They would go on to fight terrible wars against the Yithian civilization which flourished on Earth much later in the Mesozoic. Some would survive hidden even into the 20th century. (The Shadow Out of Time - H. P. Lovecraft)

Paleozoic Era (541 - 251 million years ago)

 * 500,000,000 BC: The Krell civilization flourishes on Altair IV. (Forbidden Planet)
 * On Earth, the Elder Things fight against the Spawn of Cthulhu. (At the Mountains of Madness - H. P. Lovecraft)

Mesozoic Era (251 - 66 million years ago)

 * The Great Race of Yith inhabits Earth and wars against the Flying Polyps. Meanwhile, the Elder Things are still active on the planet, now fighting against the Mi-Go as well as dealing with the first Shoggoth rebellions. (H. P. Lovecraft)
 * The Silurians and Sea Devils flourish on Earth. (Doctor Who)
 * The intelligent Voth evolve on Earth, but leave the planet en masse to escape a natural catastrophe. (Star Trek)
 * Earth is visited by aliens assuming the appearance of dinosaurs known as "Rainbow Faces" in order to blend in with the natives. (The Land Before Time VII: The Stone of Cold Fire)
 * A family of Spiders arrives on Earth during the Jurassic. (The Grim Adventures of Billy & Mandy)
 * "It" leaves the Macroverse and crash lands on what will soon be Derry, Maine on Earth and becomes dormant for the next several million years. (It - Stephen King)
 * 140,000,000 BC: The Vardon-Kosnax War occurs and Xeriphas is caught in the cross-fire and devastated. The surviving Xeraphin take refuge on Earth. (Doctor Who)
 * 100,000,000 BC: The Doctor has suggested this as the date when the moon started orbiting the Earth. Possibly the reason why the Silurians and Sea Devils entered hibernation. (Doctor Who)
 * 100,000,000 BC: The Thing crash lands on Earth in the Arctic where it became frozen in ice for millions of years. (The Thing)

Paleogene Period (66 to 23.03 million years ago)

 * 60,000,000 BC: A Xylok ship crash-lands on Earth and the crystalline crew becomes trapped within the Earth's crust. (The Sarah Jane Adventures)

Neogene Period (23.03 to 2.58 million years ago)

 * 20,000,000 BC: The Voth settle on the Delta Quadrant and forget about their earlier history. Their descendants consider themselves native to the quadrant and refuse to believe that their ancestors could have been refugees. (Star Trek)
 * 12,000,000 BC: A member of the Fendahl species escapes its doomed homeworld and finds its way to Mars, provoking a mass extinction, before settling on Earth where it influences the development of primitive Humans. (Doctor Who)
 * 10,000,000 BC: The Forerunner - Precursor war happens rendering the Precursors almost extinct and The Forerunners take the mantle of responsibility by force. (Halo)

Pleistocene Epoch (2.588 million to 11,700 years ago)

 * Circa 1,500,000 BC: The Vorlons create an interdimensional gate and make contact with the Thirdspace Aliens for the first time. (Babylon 5)
 * Circa 497,740 BC: An unknown alien race creates the Vindrizi. (Babylon 5)
 * 450,000 BC: After colonizing Nibiru, the Anunnaki colonize Earth in search for exotic minerals. (Ufology)
 * Circa 400,000 BC: A Vinean ship arrives on Southern Europe and colonists build subterranean settlements for themselves. Most remain in suspended animation, however. (Yoko Tsuno)
 * 250,000 BC: A meteorite falls in Alaska containing Parasitic Ice Worms which would remain dormant until being accidentally released in 1993. (The X-Files)
 * 100,300 BC: The Forerunner - Flood war begins. (Halo)
 * 100,000 BC: The Forerunners fire the Halo arrays destroying all life in the Galaxy and ending the Forerunner - Flood War. All the species in the Galaxy were preserved on the Ark including Humans which are put back on Earth and are back to a very primitive state. (Halo)
 * The intergalactic emperor Xenu decides to freeze the inhabitants of the 76 planets owned by the Galactic Confederacy as a solution to the planet's overpopulation problem and to prevent being overthrown. He then travels to Earth with the frozen aliens to drop them in a Hawaiian volcano and detonated it with various nuclear bombs. The Thetans from the deceased aliens were then captured by Xenu, brainwashed, and left on Earth where they would later merge with early humans. (Scientology)
 * 59,000 BC: The height of the Gubbage Cone empire, encompassing numerous other species including the Ogrons and the Ice Warriors. (Doctor Who)
 * 35,000 BC: Two cavemen in North Texas, Earth are attacked by a long-clawed alien. One of the men is killed while the other becomes infected with the Purity. (The X-Files)
 * Circa 20,000 BC: Two Krynoid pods fall on Antarctica. (Doctor Who)
 * Circa 16,000 BC: The Trigannon Sancreda is stranded on Earth, in the region that would become Cornwall. (Doctor Who)
 * 15,000 BC: Estimated time in which prehistoric civilizations on Egypt were visited by the Martian Thoths. Thousands of years later, the ancient Egyptians would derive their image of the eponymous god from these memories. (Valley of Dreams).
 * The Great Gazoo is exiled to Earth and befriends local cavemen. (The Flintstones)

9th millennium BC

 * Circa 8015 BC: The Antareans have an outpost on Earth known as Atlantis, which ends up collapsing due to a cataclysm. Twenty Antareans are left behind and cocoon themselves to wait until their eventual rescue. (Cocoon)

8th millennium BC

 * Circa 7800 BC: The Ralgans evolve to the point of transitioning from a corporeal to a non-corporeal existence. Sadly, the Soul Hunters misinterpret this as the Ralgans dying en masse and attempt to collect their "souls", inadvertently trapping all Ralgans in one of their soul globes. (Babylon 5)

5th millennium BC

 * Circa 4800 BC: Estimated time of the creation of the first jumpgates, by an unknown alien race. Also the dawn of the Hyach civilization on Shir-shraba. (Babylon 5)

4th millennium BC

 * 3800 BC: Dawn of the Abbai civilization on Abba IV. (Babylon 5)

3rd millennium BC

 * Circa 3000 BC:
 * The first neutronium-based life forms evolve on the surface of the neutron star named Dragon's Egg. Over two thousand years later, they would give rise to the intelligent Cheela. (Dragon's Egg)
 * The alien Ankh-Venharis makes contact with the ancient Egyptian civilization on Earth. (Time Walker)
 * Circa 2800 BC: Dawn of the Yolu civilization on Pa'ri. (Babylon 5)
 * 2200 BC: The San'Shyuum civil war begins. (Halo)
 * 2100 BC: The San'Shyuum civil war ends. (Halo)
 * The Mondoshawan arrive on Earth in ancient Egypt to hide the four stones and the Fifth Element for them to be guarded by a lineage of priests. (The Fifth Element)

2nd millennium BC

 * Circa 1300 BC: Dawn of the Markab civilization on Septis. (Babylon 5)

1st millennium BC

 * 938 BC: Beginning of the Sangheili - San'Shyuum war. (Halo)
 * 852 BC: The Sangheili - San'Shyuum war ends resulting in the two species forming the Covenant.
 * Circa 800 BC: Dawn of the Drazi civilization on Zhabar. Meanwhile, the Yolu of Pa'ri achieve interstellar spaceflight for the first time. (Babylon 5)
 * 784 BC: The Taming of the Lekgolo occurs where the Lekgolo are incorporated into The Covenant.
 * Circa 50 BC: War between the Tadsylwiens and the Nagma. (Asterix and the Falling Sky)

1st century

 * AD 33: In Jerusalem, Earth, Brian Cohen falls from a tower but is inadvertently saved by the passing of a starship piloted by aliens. (Monty Python's Life of Brian)
 * AD 79: The eruption of Mt. Vesuvius destroys Pompeii along with the alien Pyroviles. (Doctor Who)