Age of Exctinction
Although Megatron's spark had been extinguished in the battle for Chicago, his brain remained intact within his severed head. A few years after the Chicago war, Megatron's remains were acquired by KSI, who forced Brains to download and decrypt data from the Decepticon leader's brain to help them crack the secrets of Transformium and crate their own range of man-made Transformer drones. Company head Joshua Joyce intended for the centerpiece of this line, the military drone "Galvatron," to be physically patterned after Optimus Prime, but Megatron's still-functional mind secretly influenced the Transformium, causing it to take a shape not dissimilar to his own appearance, so that the Galvatron shell could serve as a new body for himself. Additionally, he learned of KSI's alliance with the Cybertronian bounty hunter Lockdown, and the cyberforming Seed they were going to received as payment, and schemed to steal it and use it to create enough Transformium to build a massive Decepticon army. As the go-between, Brains was aware of the Decepticon leader's plan, but declined to notify his captors of any of this, because seriously, screw those guys. After four prototype Galvatrons were junked by KSI due to their "inexplicably" Megatron-like appearance, they were forced to put the fifth into action after the Autobots attempted a raid on their Chicago facility. Before it rolled out, Megatron transferred his mind into the drone's body (or, as Brains put it, "infected it with his evil nasty chromosomes") and was thus reborn, a spark-less, soul-less 'bot without fear. He initially pretended to obey KSI's remote control, but quickly began to exhibit his free will, firing his weapons unbidden and showing a reckless disregard for civilian bystanders. When Optimus Prime engaged Galvatron in battle, he could sense the essence of Megatron within the drone, but before their fight could reach a definitive end, Lockdown interceded and abducted Prime. Galvatron was retrieved from the field by a furious Joyce, who declared the drone's signs of autonomy as critical flaws. Brains revealed Galvatron's scheme to Cade Yeager, who called Joyce and alerted him of the danger Galvatron posed should he obtain the Seed. Having ended his deal with Lockdown, Attinger handed over the Seed he'd received in exchange for Optimus. Though efforts were made to tighten security, Galvatron activated on his own as he bellowed his name, then animated KSI's other Transformers. Together, Galvatron and his new minions trashed KSI's lab as they searched for the Seed. However, Joyce was able to flee the facility with the Seed, escaping both Galvatron and the CIA. He attempted to rendezvous with the Autobots and Yeagers in Hong Kong. Galvatron ordered his new Decepticons to split up and find Joyce, and his troops were able to shoot down the Autobot ship just as Joyce was about to hand over the Seed. The Autobot ship crash-landed in the nearby Wulong Valley, leaving only Hound and Bumblebee to protect the humans and the Seed. However, just as the two were about to be overwhelmed, the other Autobots returned with the Dinobots in tow, quickly turning the tide of battle and slaying most of the Decepticons, much to Galvatron's chagrin. Galvatron was only saved by the timely reappearance of Lockdown, whose attack drew Optimus's attention. With his plans temporarily stymied, Galvatron declared his rebirth and swore revenge against Prime as he left for parts unknown.
The Last Knight
At some point, under undivulged circumstances, Galvatron fell under the sway of the the alien sorceress and supposed Cybertronian "goddess" Quintessa, took on a new jet alternate mode, and returned to using his true name "Megatron". See Megatron (Movie).