Autobots

The Autobots (autonomous robotic organisms) are the second Cybertronian civilization, being the descendants of the early workers who served the Dynasty of Primes. Following the outbreak of the war, the Autobots became the Transformers who rallied around Optimus, the last of the Primes, to prevent Protector Megatron from claiming the All Spark. They were formed mostly from the Science Division, the Security Force, and what few members of the Defense Force rejected Megatron's violent ambitions. Although they fought valiantly, the Decepticons were more warlike, and they began to gain ground. In a move to prevent the Decepticons from acquiring the All Spark, Prime sent it hurtling into deep space. Megatron followed, and disappeared. The Autobots then scattered among the universe, searching for the All Spark.

Following some twelve thousand years of searching, the Autobots encountered a stranded human vessel in space. Known as Ghost One, the creatures aboard, named humans, revealed that they had developed the ship based on studies from Megatron. Recognizing that Megatron would destroy their world if he came back online, Optimus tried to send them back to Earth, but they sacrificed their lives to save Optimus from Starscream. Already suspecting that the All Spark was on their homeworld, the Autobots made efforts to find Earth.

Eventually, the Autobots made their way to Earth, discovering a link to the All Spark with Sam Witwicky. The Autobot Bumblebee came into Sam's possession, and contacted Optimus Prime. Prime came to Earth with Jazz, Ironhide, and Ratchet to retrieve the All Spark and eliminate Megatron, fearing the Decepticon would use the Cube to raise an army from human technology. However, Starscream's retrieval team was also on Earth, having come for the All Spark. The Autobots were further hampered by Sector Seven, the human agency tasked with dealing with Transformers. Eventually forming a brief truce with Sector Seven and a group of Army Rangers who had encountered Blackout and Scorponok, the Autobots fought off the Decepticons in Mission City, which saw the deaths of Megatron, Blackout, Bonecrusher, and Brawl, but Jazz was killed and the All Spark destroyed when Sam Witwicky extinguished Megatron's spark. Without a means to restore Cybertron, the Autobots decided to remain on Earth, and Optimus Prime sent a message into space for Autobots to come and protect their new home and newfound allies in humanity.

Over the next two years, more Autobots began making their way to Earth, such as Arcee, Sideswipe, Jolt, Salvage, and others, joining a human military force known as NEST. Under the classified Autobot Alien cooperation act, the Autobots entrusted the remaining All Spark shard to humanity and gave them intelligence about the Decepticons they were facing. However, the Autobots refused to share weapons technology with humanity, knowing their history internecine warfare.

In 2009, NEST had five encounters with the Decepticons on different continents, indicating that the Decepticons were searching for something. During a sweep of Shanghai, NEST encountered Demolishor and Sideways, who caused substantial damage to the city during their attempts to escape. Although they were neutralized, Demolishor relayed a warning to Optimus Prime: "The Fallen will rise again". Following this, NEST returned to their base of operations at Diego Garcia, where they relayed the warning to General Morshower and Director Galloway. Having been appointed liaison by the President, Galloway concluded that the Decepticons only interest in Earth was to hunt down the Autobots. Unfortunately, Galloway also revealed both Megatron's resting place and the presence of the shard on Diego Garica. Soundwave was listening to the briefing, and directed Ravage and the Constructicons to raise Megatron. Meeting with his master, The Fallen, Megatron was commanded to retrieve Sam Witwicky, who had absorbed the knowledge of the AllSpark, and kill Optimus Prime, the only one who could defeat The Fallen. Optimus died helping Sam escape, and the Decepticons launched multiple attacks to have the humans turn Sam over to them. Galloway used the attacks as an excuse to have himself placed in charge of NEST and place the Autobots under guard.

Meanwhile, Sam, his girlfriend Mikaela Banes, and his roommate Leo Spitz were being hidden by Bumblebee and the Twins Skids and Mudflap, and with help from Seymour Simmons of Sector Seven, discovered Decepticon-turned-Autobot Jetfire, who told them that the Fallen, one of the founders of the Dynasty of Primes, was looking for the Matrix of Leadership needed to activate the solar harvester, which would destroy Earth's sun and make energon. Sam was able to find the Matrix and use it to revive Optimus Prime, who, armed with the knowledge of his family and parts from the dead Jetfire, managed to destroy the harvester and kill the Fallen, saving Earth.