A timeline for the events of the Unicron Trilogy cartoon universe. Significant differences between the English and Japanese continuities are highlighted.
The Dawn of Time
Nine billion years ago, Primus becomes Cybertron and creates the thirteen original Transformers, including Vector Prime. Following Unicron's defeat, the Transformer race expands, and peace settles in. Vector Prime withdraws from the linear universe, observing the passage of time across the multiverse from outside of the timeline.
The specifics of the early days of Transformer civilization are murky. At some point, the race splinters into the Autobot and Decepticon factions, and some degree of enmity forms between the two sides. It is unclear if any formal warfare is waged, but at least some fighting between the factions is recorded. Eventually, however, the two sides attain a peaceful co-existence, but they never manage to re-integrate into one aligned faction and continue to wear their individual insignias. 
The Transformers attempt to establish a colonisation program, using four massive starships to transport groups of Cybertronians across the galaxy to four selected worlds, with the intention of using Cyber Planet Keys imbued with the power of Primus to reshape them and connect them via a space bridge network. However, as the result of some unspecified incident, the plan fails, and contact with the four colony worlds of Velocitron, Jungle Planet, Gigantion and Earth is lost. As time rolls on, they become forgotten by Cybertron at large. The four worlds evolve their own Transformer societies, whose descendants are likewise unaware of Cybertron, considering it a legend at best.
Unicron attacks Cybertron once more, but is defeated by the legendary warrior, Omega Supreme. Subsequently, Omega and the four "Maximus" combiners enter hibernation beneath the surface of Cybertron, with the combiners guarding a reservoir of Super Energon.
10,000,000 years ago
Unicron disguises his dormant body as Cybertron's moon, hiding in plain sight.
Around this time, peace between the Autobots and Decepticons finally collapses, and the millennia-long Cybertronian civil war begins. 
4,000,000 years ago
Unicron implants some of his cells inside Cybertron, where they gestate and become a new race of diminutive robots called Mini-Cons. However, an encounter with a group of time-displaced human children mere moments after their creation plants the seeds of sentience within the Mini-Cons.Just as the chaos-bringer had planned, the emergence of the Mini-Cons only causes the Transformers' war to escalate, as both sides vie for control of the power-enhancing abilities that the Mini-Cons possess. At least one account notes that Cybertron underwent some undetermined form of "cataclysm" shortly before the emergence of the Mini-Cons—presumably, this accompanied Unicron's implantation of his cells within the planet.
Eventually, thanks to their experience with the human children, the Mini-Cons attain true sentience and decide to choose their own destiny, intending to head for the planet Earth. The Autobots aid the Mini-Cons in escaping Cybertron aboard the spaceship Exodus, but the Decepticons attack in the midst of the escape attempt. As the Exodus warps away, it is struck by a blast and crippled, and when it emerges from the portal in the Sol system, it scrapes across the surface of Earth's moon, and is torn in two. The bulk of the craft remains on the lunar surface, but a portion of it tumbles to Earth, scattering its Mini-Con passengers—sealed in stasis panels—across the planet.
8000 years ago
In the midst of the civil war on Cybertron, an Autobot commander named Rodimus tires of the endless conflict and gathers up a group of like-minded Cybertronians, leading them into space to escape the corrosion of war without end. Both Autobots and Decepticons accompany him, laying down their arms and working together to mine energon. Rodimus leaves them to this new life they have chosen, and continues on his interplanetary voyage of peace. The miners are transformed by the power of energon into Omnicons.
- For further information, see: Rodimus's crew
Optimus Prime rises to prominence as a great leader after Rodimus's departure.
Indeterminate millennia/centuries ago
On Earth, many ancient human civilizations come into contact with the Transformers living on the planet. The colony ship that came to this world, the Atlantis, inspires the legend of the sunken city when it malfunctions and falls from the sky. The Decepticons from the Atlantis inspire many legends in their own right, becoming the basis for most of Earth's monster myths. They are captured by Crosswise and sealed in stasis deep beneath the Earth's surface in the Arctic.
In later centuries, Mini-Con stasis panels are discovered by various cultures, and whether by ironic coincidence or Unicronian design, they produce violence and conflict wherever they are taken. At some point, an unknown civilization acquires the three panels that make up the mighty Star Saber sword, but they use its power to wage war on another culture, who strike back with the power of the Skyboom shield. The energies released cause the city to sink beneath the ocean, and the six Mini-Cons are again lost. Epochs later, in the Sahara desert, the mysterious influence of the panel containing Bonecrusher allows for the creation of a vastly technologically-advanced temple, full of futuristic mechanical traps, in which the panel is sealed.
In a parallel dimension, the warmongering inhabitants of Planet X open a wormhole and pull the colony world Gigantion through to their universe, intending to strip it of its resources.  The Gigantions use the power of the Cyber Planet Key to enlarge themselves and their planet to fight back, forcing Planet X to employ its mightiest weapon, only to wind up destroying itself in the process.
As both sides of the conflict steadily gather Mini-Cons all over Earth and more troops arrive from Cybertron, Sideways arrives on Earth to manipulate the conflict to Unicron's ends. The components of the Star Saber and Skyboom are located and the weapons are re-formed, only to both fall into Decepticon hands thanks to Sideways's side-switching machinations, but before long, he arranges for the Autobots to obtain the Skyboom. Eventually, however, his schemes are discovered by Megatron, and he is ousted from the Decepticon ranks.
Exploring the caves outside their hometown, Rad White and Carlos Lopez discover that they are, in fact, the cavernous remains of the Exodus. They inadvertently reactivate the ship's systems, and Mini-Con stasis panels begin reactivating all across Earth. A signal relaying this fact is beamed across the galaxy to Cybertron, and the evil Megatron promptly leads a small team of Decepticons to Earth via warp gate in order to gather up the Mini-Cons for themselves. Optimus Prime pursues him with his own contingent of troops, and these Autobots befriend Rad, Carlos and their friend Alexis, who have developed a telepathic bond with the Street Action Mini-Con Team.
The arrival of the massive Decepticon battleship Tidal Wave coincides with the Autobots' successful formation of the final Mini-Con weapon, the Requiem Blaster. Using the power-hungry Thrust as a go-between, Sideways orchestrates a plan that allows the Decepticons to acquire the Requiem Blaster, while at the same time betraying Starscream, who takes the Star Saber and joins the Autobots. After the successful liberation of the Decepticons' captive Mini-Cons, however, Starscream is convinced to rejoin Megatron's forces, bringing the Star Saber and Skyboom with him, finally putting all three weapons in the Decepticons' hands. Using them, they create the Hydra Cannon, but Optimus Prime dies stopping the weapon from destroying Earth.While this conflict plays out, various other Mini-Cons activate across Earth, including the Super Stunt Team, who form a bond with the human Stella Holley. Joining with their fellow Mini-Cons, the Sonic Assault Team, against the evil Unicron-aligned Speed Chaser and Aqua Raider Teams, the Mini-Cons' adventures lead them to discover the "Master Key" program, which they use to unlock the full power of all the Mini-Cons on Earth.
As the Decepticons head back to Cybertron, they are pursued by the Autobots, now under the leadership of Hot Shot and the fully-empowered Mini-Cons. The Mini-Cons use their new powers to resurrect Optimus Prime, and to transform the bodies of several Autobots and Decepticons into new "Powerlinx" forms after they are injured in battle with another of Unicron's minions, Nemesis Prime.
The Transformers subsequently return to Cybertron, where Sideways and Thrust steal the Mini-Con weapons High Wire to the moment of the Mini-Cons' birth, completing the circle. As the evil demi-god attacks Cybertron, Starscream sacrifices himself to convince the Autobots and Decepticons to ally against him. Although Unicron brings the Mini-Cons back under his control again, the bond between them and the kids allow them to overcome his influence, and the Mini-Con weapons are liberated, deactivating Unicron once more. With Unicron apparently defeated, however, Megatron (now Galvatron) challenges Optimus Prime to one final battle, only for the hatred embodied by their conflict to reactivate Unicron once more. Galvatron opts to perish rather than live in an age of peace and plunges into Unicron's jaws. With this act bringing about the end of the Cybertronian war, there is no longer any force to sustain Unicron, and he vanishes in a flash of light.and use them to reactivate Unicron's dormant body. The Mini-Cons' origins as Unicron's creations are revealed, and Rad, Carlos and Alexis are sent back in time by
In the wake of this battle, Optimus Prime no longer considers himself worthy of the Matrix of Leadership, and embarks on a soul-searching space voyage.
2010 to 2020
The relative chronological placement of these events is uncertain.
At some point, Optimus Prime returns to Cybertron and reclaims leadership of the unified Autobot and Decepticon forces.
Peace between the Autobots and Decepticons does not come easy, with determined villains such as the brothers Shockblast and Six Shot attempting to renew the hostilities, even to the point of attacking Decepticons themselves. They are eventually imprisoned.
Unbeknownst to the Transformers, Unicron has survived his apparent destruction, and continues to consume planets in the far reaches of the universe. Attacking the world known as Planet Q, Unicron is badly damaged when the planet self-destructs, and he is knocked offline. However, the spark of the planet's ruler, Alpha Q, still lives within Unicron.
A delegation of humans, including the Autobots' existing human allies, Dr. Brian Jones and his son Kicker, comes to Cybertron to establish friendly relations between Mankind and the Transformers. Kicker is terrified of the Transformers and flees, stumbling into an underground chamber and reawakening Primus. Primus bestows upon Kicker the ability to sense energon, leading to the discovery of the mineral in various locations on Earth, on Mars and in the asteroid belt. Massive "Cybertron Cities" are constructed at these sites, where Omnicons mine the energon as part of a "clean energy" program for Earth and Cybertron.
Seeking to use the power of energon to recreate Planet Q, Alpha Q creates the Terrorcons out of Unicron and sends them to attack the Cybertron Cities and gather the mineral for his plan. The Autobots fight back using the new combination powers given to them by Primus, and in retaliation, Alpha Q creates Scorponok and the Energon Sword in order to turn the Decepticons to his side. The plan works, but soon, Megatron—his body trapped within Unicron's dormant husk—steals enough of Alpha Q's energon to engineer his own resurrection. Megatron continues Alpha Q's plan to gather energon, this time with the intention of repairing Unicron and using him as a weapon. Alpha Q escapes in Unicron's head and uses what little energon he has left to resurrect Starscream to act as his minion, but Megatron uses Unicron's powers to wipe Starscream's mind and turns him into a Decepticon once more.
After protecting Earth with an energon grid, the Autobots embark aboard the Miranda II to stop Megatron and destroy Unicron. They are joined by Rodimus, who helps them understand Alpha Q's true objective, and Kicker is able to convince the alien to join with the Autobots in fighting the Decepticons. The Autobots lure Unicron into their space bridge, teleporting the giant to the vicinity of Cybertron, but Megatron uses this opportunity to reveal to the Decepticons on Cybertron that he still lives, turning them on the Autobots. Shockblast is liberated from prison and joins Megatron's army, but quickly makes plans to take over.At the height of a battle in the skies above Cybertron, Alpha Q initiates a reaction between Unicron's energon and the energon of Earth, tearing a fissure in space and recreating many of the planets Unicron has destroyed. In this new region of space, Megatron and the Decepticons attack the newborn planets and gather up enough energon to re-energize Unicron. To aid the Autobots, Primus and Dr. Jones reawaken Omega Supreme, who combines with Optimus Prime to combat a Unicron-possessed Shockblast. When Shockblast is ultimately destroyed, Megatron too falls victim to possession by the dark god, and to combat the threat, Primus super-charges "Optimus Supreme", enlarging him to planet size and enabling him to destroy Unicron's body once and for all.
Unicron's consciousness continues to exist within Megatron, and drives him to uncover the reservoir of Super Energon, which transforms him into Galvatron again. In the process, Galvatron awakens the "Maximus" combiners; Superion Maximus joins the Autobots, while Constructicon Maximus and Bruticus Maximus side with the Decepticons, just as the villains are joined by Shockblast's younger brother, Six Shot. Using Six Shot's technical skills, the Decepticons shroud Cybertron with energon gas and move the planet back into Alpha Q's star system. There, Galvatron uses the Super Energon to enlarge himself to planet-size, at which point Unicron takes over his body once more. As Galvatron struggles for control, Primus uses the Super Energon to create a new sun for Cybertron, and Galvatron, preferring to die than be a servant, plunges himself into the sun, containing Unicron's spark within it. Starscream follows his leader into the sun.
2020 to 2030
For unexplained reasons, the Autobots withdraw from Earth entirely. All record of their existence is suppressed, and among humans, stories of them become, at best, urban legend.
Most of the Mini-Cons relocate to Cybertron's moons, establishing colonies where they can finally live in peace.
Primus’s sun eventually collapses in upon itself, becoming a colossal black hole so powerful that it disrupts the fabric of reality. With Cybertron in crisis, Vector Prime emerges from beyond time to inform the Autobots of the lost Cyber Planet Keys, which hold the power to close the black hole. Megatron and Starscream are also restored, and Megatron seeks the power of the keys to accelerate the universal degeneration caused by the black hole and remake the cosmos in his own image. The populace of Cybertron is relocated to Earth, where Optimus Prime’s elite Autobot team befriend Coby and Bud Hansen and their friend Lori, who aid them in locating the Omega Lock, the focusing device for the Cyber Planet Keys’ power. With new "Cyber Key Powers" awakened in them, the Transformers search for the Lock on Earth, while Hot Shot and Red Alert head for Velocitron, competing in the planet's grand racing championship to win the key from planet leader Override.
While Prime's team follows Vector Prime's directions, other Autobots are dispatched to the four corners of the universe to search for the keys the hard way. A team commanded by Longrack investigates the planet Combatron, where they clash with a Decepticon unit led by Brushguard.As the search for the keys progresses, Vector Prime reports on the Autobots’ progress to Alpha Trion on Cybertron. During one such trip, however, the planet comes under attack from two of Unicron’s heralds, Ramjet and Nemesis Prime, who intend to destroy the under-protected Primus with the Dead Matrix. Alpha Trion uses the spatial instability caused by the Unicron Singularity to summon Sentinel Maximus from another dimension, and together, he and Vector Prime battle the heralds, and are able to successfully defeat them with help from another interdimensional guest, Omega Prime. The Dead Matrix, however, is stolen by Planet X's Soundwave, who casts it into the Unicron Singularity, freeing Unicron’s spark. Infesting the planet Yst, Unicron destroys the planet from within and is reborn in a new (much smaller) body.
Shortly after the Omega Lock is located on Earth in the bulk of the crashed spaceship the Atlantis, Overhaul heads for the Jungle Planet, where the power of its Cyber Planet Key reformats him into Leobreaker. Megatron ingratiates himself with Jungle Planet ruler Scourge, while at the same time, Starscream, working towards his own goals, teams up with the returned Sideways.Ultimately, the Autobots succeed in acquiring the Keys of both Velocitron and Jungle Planet, at which point the existence of Earth's own Cyber Planet Key is revealed. Starscream makes his power play and overthrows Megatron, stealing the Omega Lock and all three keys from the Autobots and using them to grow in size and power. Their forces bolstered by the ancient Autobots from Earth and the arrival of Wing Saber, who combines with Optimus Prime, the Autobots fight their way through a vengeful Megatron and defeat Starscream - but the battle is not without casualties, as Hot Shot, Red Alert and Scattorshot are gravely wounded and rebuilt into the even more powerful "Cybertron Defense Team".
At the same time, on Cybertron, news reaches the Autobots there of a war that has erupted between the two factions of Mini-Cons living on the planet’s moons. Offering to help, the Autobots join the conflict, but before long, Unicron also enters the fray, intending to terminate his rebellious creations.Starscream attempts to tap the power of Primus and grows to planetary size, only to be defeated by Primus himself. Simultaneously, Optimus Prime’s Autobots return to Cybertron and use the Omega Lock and Cyber Planet Keys to awaken the spirit of Primus, causing Cybertron to transform into the god's body. This awesome sight brings the battle on the moons to a screeching halt, and Unicron flees. Soon, the Autobots identify the location of Gigantion, while the Decepticons have to be led there by Soundwave. Bested by the planet's leader Metroplex, Megatron taps the key's power to become Galvatron yet again, and blasts Starscream, Sideways and Soundwave into another dimension to acquire the Lock and Keys for himself. Vector Prime sacrifices his life to allow the Autobots to return to their home universe, and the five planet leaders confront Galvatron within the black hole and defeat him. With all the Cyber Planet Keys now in his possession, Primus uses their power to finally seal the black hole, ending its threat.
As the planet's various civilizations attempt to return to life as normal, Galvatron attacks the Autobots for one final time. Without any troops to call his own, Galvatron engages Optimus Prime in a one-on-one duel, and is finally destroyed for good.With this final victory, Optimus Prime begins a new space bridge initiative, and the Transformers set sail for the four corners of the universe, and new adventures.
- ↑ Transformers from this period such as Omega Supreme, the Maximus combiners and those who travelled on the four starships wear the Autobot and Decepticon symbols and recognise and ally themselves with their respective factions after re-emerging in the modern day. The hatred between the Maximus combiners (two Autobot, two Decepticon) and the mural in the Super Energon shrine proves there was conflict between the factions in the past, but the eventual rise of peace is demonstrated by the joint ventures that both sides participated in, such as the colonisation program, and the Maximus combiners guarding Super Energon together.
- ↑ Though the Energon episode "Omega Supreme" simply says that Omega Supreme fought Unicron while searching for Energon, the Superlink version of the episode explains that Omega Supreme and Primus fought Unicron in this era.
- ↑ 3.0 3.1 Date for this period from timeline on Takara's website.
- ↑ "Planet X" write up on Cybertron Soundwave's toy packaging.
- ↑ In the episode "[[Revelation (Cybertron episode)|]]" set in 2030, Thunderblast mentioned having been imprisoned for 30 years.
- ↑ The Transformers Energon Official Guidebook indicates Kicker was 8 when he first visited Cybertron, and 16 when Energon began.
- ↑ Jetfire's Cyber Key Code information, on Hasbro.Com