Vector Sigma

The super computer that gave all Transformers life, Vector Sigma dwells deep within Cybertron were he sleeps, guarded at one time by military like drones.  Though only a select few Transformers know of his existence, and even fewer know how to get to his chamber, only the Autobot Alpha Trion possessed the key to activate him.

For millions of years, Vector Sigma slept until Megatron needed his help to activate the powerful Stunticons.  Megatron found Alpha Trion, and took the Key from him, and used Vector Sigma to activated the Stunticons.  Optimus Prime and the Autobot's followed the Decepticon's, but were too late to stop them.

Optimus Prime decided to create the Aerialbots, and took them to Vector Sigma to activate.  Unfortunately Megatron had taken the Key back to Earth with him, so Alpha Trion gave his own life to activated Vector Sigma, thus merging himself with the super computer.

Vector Sigma was then left alone, until the Earth Year 2006 when Optimus Prime used the shell of the Matrix of Leadership to temporarily merge with the super computer in order to speak with Alpha Trion, who told him that Vector Sigma was the one that told Galvatron the location of the Key to the Plasma Energy Chamber, and that a new Golden Age of Cybertron would soon come to be.  Not long after that the prophecy came true.

It should be noted that the Key to Vector Sigma has the power to transform organic matter into inorganic matter.  When he found out about this power, Megatron sought to use the Key to change Earth into a new Cybertron.  But thanks in part to the Aerialbots leader Silverbolt, the Key was destroyed.  This however was not the last time that the Key was to play a part in the history of Cybertron though.  During the battle to save Cybertron from Megatron (the one from the Beast Wars/Beast Machines), the Vehicon Tankor (who carried the Spark of the former Maximal Rhinox) used the Key in his plans to destroy the Maximals, and bring Megatron to his knees.  However, it was deemed risky to use the Key after it was found out the Optimus Primal was able to open the Plasma Energy Chamber.  And to this day, the Key has not been seen.