Disclaimer: I don't own Transformers, G.I. Joe, Avatar: The Last Airbender/The Legend of Korra, Godzilla, Gamera, Spawn, Teenage Mutant Ninja Turtles, Power Rangers, and the various Marvel characters and DC characters. They all belong to their respective owners, and while the idea of each of them being in a shared universe is nothing new, this is just my take on it.

A/N: This section mixes various continuities, but takes more hints from the Prime and IDW Publishing G1 universes.

Transformers

Long ago, on the planet that would come to be known as Cybertron, a being whose origins are shrouded in mystery created six beings to shape this world. These six would be known as the Guiding Hand. They were:

Primus, the giver of life, light and order

Unicron, bringer of obligatory chaos and unpredictability

Mortilus the death-bringer, and the necessary corollary to life

Adaptus, blessed with infinite shapes

Epistomus, knowledge personified

Solomus, wisdom incarnate.

With but a gesture, the Guiding Hand spawned the first Cybertronian race. Under their reign came the First Golden Age of Cybertron which was shattered when Mortilus and Unicron believed that the Guiding Hand should become a fist against the rest of the universe. As Mortilus and Unicron stood against Primus, all of Cybertron became divided in a conflict that saw the planet shudder and its first moon being ripped asunder. The Death-bringer was ultimately destroyed in the struggle, and the Chaos Bringer was cast to the stars by Primus' children, but the conflict left the remaining members of the Guiding Hand mortally wounded.

Primus who was near death went into the heart of Cybertron where he re-integrated himself to the planet and became both the planet's core and Vector Sigma, the source of all sentience. Solomus was trapped by Mortilus into a crystal prison but the wise god managed to re-arrange it into the Creation Matrix that not only served as a connection to Vector Sigma but provided wisdom to future generations of Transformers. Both Epistomus and Adaptus were not as fortunate, as Mortilus had stripped both bare. Epistomus was transformed into a brain module whilst Adaptus became a transformation cog. Prior to their death, they offered their designs to future generations to utilize both their intelligence and functionality to face the rigors of their environment. With Mortilus' destruction, death itself was gone and this allowed the sparks of Cybertronians to burn eternally, rendering them functionally ageless.

After the defeat of Unicron and the destruction of Mortilus, Primus' first thirteen children, who would later be called the Knights of Cybertron, went on to guide the populace of Cybertron. The Thirteen of them were as thus:

Prima, who was the first Matrix-bearer, the first Transformer born from Cybertron, leader of the Thirteen; he was a warrior of light who used a Star Saber with the Matrix as its hilt.

Alpha Trion, who can see the past, present, and future, and who holds the Covenant of Primus and the Quill; he maintains a close relationship with Primus through Vector Sigma.

Solus Prime, the first female of the Cybertronian race, and a weaponsmith

Alchemist Prime, co-founder of Cybertronian civilization

Amalgamous Prime, the trickster

Liege Maximo, the manipulator

Megatronus Prime, the guardian of entropy and warrior of darkness

Micronus Prime, the first of the Mini-Cons

Nexus Prime, the first and greatest combiner, who was fascinated by change, and was a light-hearted prankster

Onyx Prime, the first transformer with a beast mode

Quintus Prime, the scientist supreme.

Vector Prime, the guardian of space and time, as well as the most idealistic of the Knights.

The Thirteenth Prime, created last, and whose raised arm united the Knights against Unicron.

Unfortunately, the Knights of Cybertron fell to the same type of fight that the Guiding hand was torn by.

Megatronus murdered Solus out of jealousy due to the fact that she favored Nexus Prime, a fact that was also disliked by Liege Maximo. With Solus' murder, Megatronus was robbed of his name and was forever more known as the Fallen. Though a terrible thing, Vector Prime considered the Fallen lashing out in a moment of anger forgivable over Liege Maximo's active plotting. What happened afterwards was the Fallen taking to the stars before his brothers could truly punish him for his actions, and the last words anyone heard him say were, "Our fates are intertwined now...Unicron."

Later, taking advantage of the disarray, Liege Maximo made his own play for power, but was ultimately defeated and imprisoned by Alchemist Prime. Neither of them were heard from again.

Consumed by grief over his fallen brothers, Vector Prime retreated to a pocket dimension he created for himself, which could only be accessed by blades that Solus had made for him. The blades were sent across the universe, never to be found.

Nexus Prime split himself up and was reformatted as five different protoforms, which would later reintegrate themselves as different members of Cybertronian society, with no memory of who they used to be.

Finally, there came a time when Prima had to relinquish the Matrix and gave it to Primus for safe-keeping until a new Prime could be found. Afterwards, the Covenant of Primus decreed that Cybertron could only have one Prime at a time.

Alpha Trion remained on Cybertron, recording these events into the Covenant, and the Guiding Hand and the Knights of Cybertron became myths doubted by some. Hiding his true identity, Alpha Trion became a master Archivist in the Iacon Hall of Records.

It was officially Primus's right to appoint the Prime and bestow them the Matrix, but gradually his children became ignorant of his presence. And soon, a line of Primes who were not bestowed the Matrix came to power, and were appointed by the people. One of the more notable ones included Nova Prime, who ruled Cybertron at a time when the population believed that their destiny lied with the stars. Nova created a ship called the Ark, where he would take a crew and explore space for suitable worlds in which his people could inhabit. He was believed to have died when the Ark disappeared in the Bensuli Expanse.

After that, the population was at a lost as to who would be the new Prime. Matters only worsened when Cybertron was invaded by the Quintessons, who then occupied the planet and enslaved its inhabitants for a time. During this time, the aliens modified the bodies of their new servants to serve their own ends, such as installing cockpits on the bodies of flying Cybertronians called the Seekers. However, the Quintessons were eventually overthrown by a member of the Elite Guard named Sentinel. With the installment of the High Council and the construction of the Space Bridges, Cybertron entered its Second Golden Age. Thus began the reign of Sentinel Prime.

However, over time the space bridges became less reliable and contact with the colonies was lost. Sentinel Prime and the Guilds instituted the caste system to slow their civilization's decline. The High Council and their Guards were in charge of law and order, but each state controlled its own militia. Alpha Trion did not approve of this, but his protests were ultimately ignored.

But as the nameless miners resorted to gladiatorial combat as an outlet for their misery, a champion named Megatron rose to challenge Cybertron's leadership. Megatron began corresponding to an Iaconian archivist named Orion Pax, who the gladiator came to be something of a mentor and brother to. This bond was broken when the High Council appointed Orion as Optimus Prime, and soon their Anti-Caste movement became a civil war for Cybertron's future. The AllSpark, an item of Primus' that helped create life on their planet, was lost to space, whole regions of the planet were laid waste, and the core of Cybertron itself was damaged by Megatron's scheming. Optimus Journeyed there, where he came face-to-face with Primus himself, and became the first Prime to be bestowed with the Matrix in ages. Primus promised that he would heal Cybertron on his own, but it would take time, which prompted Optimus to order the Autobots to evacuate the planet.

When Omega Supreme was badly injured, Optimus had him put in stasis mode and had him reformatted as a new Ark ship. Megatron left as well, with Trypticon now reformatted as the Nemesis warship.

Soon, the Autobots and the Decepticons fought their war wherever they went, with both side gaining allies on different planets. Before long, sub-groups appeared on each side; the Dinobots, Wreckers and Maximals for the Autobots, and the Constructicons, Predacons and Vehicons for the Decepticons.

The Autobot/Decepticon war reached its zenith when they all reached Earth. The human factor played a major role, with both sides gaining support from different human factions, both hero and villain alike fighting in it. The Autobot's allies were the Avengers, the Defenders, X-Men, the Fantastic Four, the Justice League, the Teen Titans, Avenging Justice, S.H.I.E.L.D. and their sister organization G.I. Joe. The allies of the Decepticons were M.E.C.H., the Cabal, the Secret Society, the Injustice League, the Sinister Six, and terrorist groups called COBRA, the Brotherhood of Mutants HYDRA.

Among the Autobots' more notable allies were Jack Darby, Sari Sumdac, Kicker Jones, Misha Miramond, Spike and Carly Witwicky, Coby Henson and Lori Reeds, who each worked with a different member of the Autobots and on various teams.

Jack Darby hailed from a small town in Nevada, and was partnered up with Arcee when he joined up with G.I. Joe. Their missions often took them overseas to Europe and the Arabic nations, fighting mostly against the Vehicons and the COBRA.

Kicker and Misha worked in S.H.I.E.L.D. along with the Wreckers and the X-Men. Most of the time, they fought the Constructicons and the Brotherhood of Mutants in Asia, thought it didn't help that it was also the main territory of the Kaiju, particularly Godzilla.

Coby and Lori worked with the Dinobots, the Maximals and Teen Titans in the Savage Land, fighting against the Predacons, Sinister Six and M.E.C.H. It should be noted that the Savage Land is likewise where the leader of the Maximals, Optimus Primal, got his beast form, which was due to the fact that it is also the home of a gigantic gorilla creature named King Kong.

Sari Sumdac, daughter of billionaire inventor Isaac Sumdac, used her father's equipment to build armor similar in form and function to a Cybertronian. She used one herself when fighting with the Witwicky's and the Defenders against the Cabal in North America.

About ten years in their stay on Earth, the War finally came to an end on the day Optimus Prime and Megatron fought each other to the death.

Once Optimus died, however, the Matrix presented itself to the young Autobot named Hot Rod, who, upon accepting it, was transformed into Rodimus Prime. Much of the Decepticon command was eliminated that day as well; save for Starscream, who, being the pragmatist that he was, stepped in as Decepticon leader, and, rather than fighting further, made a peace offering with Rodimus, where both Autobots and Decepticons would return to Cybertron and work together to restore their world. Rodimus accepted, and most of the Cybertronians left for their home world, with a few remaining on Earth because they had built lives for themselves there.

Some human heroes retired from fighting and settled down, like Jack Darby, who returned to his home town along with Arcee. Other's, like Sari Sumdac, stayed in the hero business and fought the good fight as a member or members of the major superhero groups.

It should be noted that during the war, some of the casualties on both sides were taken by other alien races, and different things were reverse engineered from the mechannical cadavers. Notable ones included, but were not limited to Mechagodzilla, the Zords controlled by the Power Rangers and their enemies.

The conflict of the Cybertronians did not end with the War's finish, however, as an old enemy had returned; Unicron. And, as it turned out, he wasn't alone, as he had a group of Cybertronian followers acting as his heralds. Among whom was the presumed-dead Nova Prime, who now called himself Nemesis Prime, and bore the Unicron Matrix of Conquest, a dark counterpart to the Matrix of Leadership.

And so began the second Great War…

A/N: Well, that's my take on the Transformers side of the shared universe I've put together. Hope you all like the ideas I've presented here. I'll show how Avatar: The Last Airbender/Legend of Korra is part of this in the next chapter.

The list of the Knights of Cybertron, that's actually the official list of the Thirteen Original Transformers. The Guiding Hand and their inheritors, the Knights of Cybertron, are groups created by IDW Publishing. For this, I included Unicron as a member of the Guiding Hand and equated the Knights with the Thirteen. The idea of Nova Prime becoming Nemesis Prime is also IDW's, but I added the part of him being a Herald of Unicron because that was in the TF Universe comics.

I know that this basis is massive, but I'm compensating for it by doing this. And I'm worried that I'm a much better plot writer than I am a scene writer. Review what you think, and if anyone feels like writing a story based on one or more of the ideas presented here, PM me.