The Transformers: Megatron Origin

Megatron Origin, a 4-issue mini-series published by IDW Publishing, details the rise of Megatron from a lowly Energon miner to the leader of the Decepticons. Also introduced is Autobot leader, Sentinel Prime and his quest to halt Megatron's actions. In the IDW timeline, the story takes place in the distant past, somewhere in between the launch of the first Ark (6.7 million years ago) and the events of Spotlight: Shockwave (less than a million years ago).

Megatron Origin issues:
#1 | #2 | #3 | #4

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