In Transformers: Age of Extinction, humans succeed in making their own Transformers robots, and Galvatron was the first robot designed by Joshua Joyce’s team. But, of course, humans are not the Creators of Transformers… In the same movie, towards the ending credits Optimus Prime says: “I send this message to my creators: leave Earth alone, for I am coming for you!”
Well, we cannot say for sure what Michael Bay and his team will think to add or change in Transformers Universe with their next movie. But we can tell you what we know from previous installments of the Transformers merchandise, and we will start with the 1980s animated series. First of all there are the Quintessons. Quintessons is a race of aliens who created Cybertron 12.000.000 years ago. They made servant robots who evolved to our known Autobots and military units who evolved into the devious Decepticons. At some point these robots rebelled and succeeded in overthrowing the rule of Quintessons.
In Transformers: Primal Scream by Marvel Comics, there is a different story. When the time begun, two gods, the brothers Primus and Unicron fought each other. Primus, the good guy, lost the first battles against evil Unicron. Trying to escape or find a way to win, Primus became a large metal asteroid, and Unicron was trapped in a similar way. In time, Primus learned to shape his prison and formed the planet we know as Cybertron. He created the Transformers to fight his battle against Unicron and win. But the evil sibling did not sit with idle hands. He learned to shape too and he formed a planet that can devour other planets. Since then, Unicron is searching the Universe to find and eliminate Primus.