DC Comics/manga origin:
The Cybertronians were created by Primus, lord of order, who intended to bring order to the chaos of warfare, making it mechanical, methodical, and codified by a specific set of rules
. Primus intended for the Cybertronians to be mindless military machines forever, but Unicron, the Chaosbringer, brought them the chaos of free will in the hopes that they would break the cycle of endless war and find peace. Unicron also reformatted them into Transformers, their shapeshifting ability bringing an element of random chaos into the universe as well as providing a means of disguising themselves to help hide from Primus.
Neither created by Primus nor built by the Quintessons, the Transformers were made by Humans--specifically a jazz trio called Metallica ((called Primus in earlier rough drafts)) consisting of Stan Busch
, Norm Al Yankovich
, and Vince D. Beers
. The Transformers were a marketing ploy consisting of Robots On Display
before they discovered Cybertron.
One faction of Transformers followed the heroic Galvatron ((G1 Galvatron redeco in G1 Hot Rod colors, particularly in that Galvatron's particle cannon barrel is silver like G1 toy Hot Rod's vehicle mode engine and robot mode forearm weapons)) until Starscream, one of Galvatron's most loyal followers and supporters, accidentally killed the Great Galvatron ((instead of Mighty Megatron)). ((So Shattered Plastic Starscream was loyal to his leader and only killed him by accident, whereas G1 Starscream was disloyal to his leader and constantly trying--but always failing--to kill him. SP Starscream killed SP Galvatron, whereas G1 Galvatron killed G1 Starscream. SP Starscream was responsible for his leader's death, much like many TransFans hold G1 Hot Rod responsible for his leader's death.))
Guilt drove Starscream into a self-imposed exile ((somewhere icy, perhaps a comet, perhaps the Arctic or Antarctic of planet Earth, perhaps Hoth (to introduce SWTF/Crossovers into the story); this icy exile mirrors G1 Skyfire's inadvertent imprisonment in ice on Earth, as well as being the opposite of G1 Galvatron's fate on the plasma-lava planet Thrull
A unicorn resurrected/upgraded Galvatron into Megatron ((redeco of BW Megatron (as animated in season one of the TV show), but mostly colored in G1 TFTM Galvatron purple, except for the Tyrannosaurus head (which becomes the robot's right arm/cannon) being the orange of G1 TFTM Galvatron's particle cannon barrel)).