Cerebros (RID)

Cerebros is simply a mindless drone who is the key to controlling Fortress Maximus. He is a Headmaster. In order for Fortress Maximus to reawaken, Cerebros must transform into the head of another robot known only by one name: the Emissary. The Emissary's only purpose is to transform into Fortress Maximus' head. Cerebros can only be awakened by an Autobot Leader: Optimus Prime. The only other Transformer who can awaken Cerebros is Scourge, since Megatron scanned Optimus Prime during his creation into a Decepticon.

Cerebros is discovered by the Build Team and Sideburn after the Decepticons destroy the tomb which Cerebros lies within. In attempt to gain Scourge's respect, Sky-Byte and the Predacons kidnap Cerebros from the Autobots.

From Teletraan I: The Transformers Wiki, a Wikia wiki.