Cybertron is the home planet of the Transformers.
According to Cybertronian religion, Cybertron was created by Primus five billion years prior to 2017. Twelve million years ago, the mysterious Talisman was on Cybertron in the possession of tribal leader Onyx Prime. Unlike the planets protected by the Solstar Order, Cybertron perfected interstellar travel before achieving a unified world peace. Four million years ago, the Great War between Autobots and Decepticons began, ultimately ending in 2012. The collateral damage that the war caused to interstellar space caused the Cybertronians to become one of the most hated and feared species in the galaxy.
Repeated Cybertronian incursions on Earth had convinced Joe Colton that one day Cybertron would destroy Earth, so he decided to strike first and wipe Cybertron off the cosmic map. He planned to do so by having Shazraella enerchange the Talisman, whose energy was anathema to Cybertronians, with Cybertron's very core, thereby poisoning all the energon on the planet. The Solstar Order detected the Dire Wraith genetics within the Red Shadows and sent four of its Space Knights to place Cybertron under quarantine, preventing the Carcerians from teleporting in reinforcements.
Deducing that Colton's group had piggybacked the signal of the M.A.S.S. Device on a Cybertronian Spacebridge, Soundwave, G.I. Joe, and M.A.S.K. replicated the method and arrived in the centre of Iacon. To obstruct any human pursuers, Colton released poisonous gas into Cybertron's synthetic oxygen atmosphere. When speaking to the Council of Worlds, Scarlett revealed Colton was headed to the core to plant something that would bring about the end of the Cybertronian people. Knowing that the Cybertronians wouldn't take a human-based threat seriously, Colton was able to outmaneuver the Cybertronian security forces and escape Metroplex into the depths of the planet. When Colton's alliance neared the core of the planet however, Cybertron unleashed bolts of lighting and the Insecticon swarm as a defense against what it perceived as an alien infection. When the cabal of villains neared the core's chamber however, Optimus Prime and Scarlett's group had already arrived and barred their path.
The resistance from both the heroes and the Council of Worlds made any chance of reaching the core impossible, prompting "Garrison Kreiger" to activate the Talisman then and there. The Talisman's magic revealed his true identity as Merklynn and turned a portion of Cybertron's underground into a copy of his lost homeworld of Prysmos. The process drained nearly half of Cybertron's energon reserves as well as causing the planet to "scream". The energon was sent out into space as a communication signal that read "Welcome. Death." and struck the slumbering form of Cybertron's ancient foe: Unicron.
The Cybertronians quickly arrested Merklynn and quarantined New Prysmos while sending Kup and Ironhide as representatives of Cybertron and the Council of Worlds. The Talisman meanwhile began to burrow down to Vector Sigma, the very core of Cybertron, seemingly intent on completing the terraforming process. When the Spectral Knights allied themselves with the Cybertronians, however, they managed to save Cybertron from being terraformed while managing to raise New Prysmos to the planet's surface.
When Unicron attacked Elonia, the Transformers managed to evacuate 2/3rds of the Elonian population to Cybertron. After his consumption of Caminus, the Chaos Bringer attacked Cybertron directly forcing the Spectral Knights to evacuate the planet and leaving the deserted world to be destroyed.