Long ago, he was the humble leader of Cybertron's science division, which studied the AllSpark, and were protected by Lord High Protector Megatron's military. When Megatron went rouge, Optimus discovered that he was the last of the Dynasty of Primes. In response to Megatron's attempts to seize the AllSpark and conquer other worlds, Optimus assumed his proper title and rallied the Autobots to stand against the Decepticons.