So, in Transformers 4, Age of Extinction, Lockdown is sent to hunt the Transformers, mainly Optimus, who is one of the Knights. To reach the conclusion of who the creator of the Transformers is, you must listen closely to Lockdown's words, watch Transformers Prime and most of the episodes. Quote from Lockdown is-"activate the dark fusion engines"- when he thinks he has Optimus in the cell, but the Autobots are preparing to escape. Now, in transformers Prime, there is Unicron, with dark energon, opposite of normal energon. When Megatron enters it into his spark, he becomes stronger. My theory is that the creator is either Primus, whose soul is Cybertron, or Unicron, master of Evil and has his own planet named Unicron. Cannot be sure, but it's a likely guess.If you have your own theory, please tell me it in the comments. I will try to add onto it, post it here, and give you a shout-out!