Galvatron

Galvatron is the leader of the decepticons in Pooh's Adventures of The Transformers: The Movie. He transforms into a laser cannon. He was once Megatron, but after losing at Autobot City and being pushed out of Astrotrain by Starscream, he was reformatted into Galvatron by Unicron. He plotted to rule the galaxy forever, but was defeated by Rodimus Prime who threw him out of Unicron's left eye chamber.

In Transformers Age of Extinction
Galvatron appears as the tertiary antagonist of Transformers: Age of Extinction, voiced by Frank Welker. Created by KSI using technology extracted from Megatron's severed head, he is originally intended by CEO Joshua Joyce to resemble Optimus Prime. However unknown to any of the humans, their tampering re-activated Megatron's spark within and he began to influence the humans to create and entire army of transformers so he would eventually hack them and rebuild his Decepticon army. He also learned of an ancient Cybertronian weapon called a "seed" which could cyberform an entire city on it's own which he desired to replicate into more but found himself under human control and renamed Galvatron. He is first deployed when Joshua is forced by Harold Attinger to activate him and send him against Optimus Prime and his team, though Galvatron proves highly effective he also proves uncontrollable as he smashes through cars and even speaks which Joshua claims shouldn't be possible. Galvatron was then called back once Attinger sent in Lockdown to handle Optimus. Later when the Autobots escaped with the Seed, Galvatron activated his army and attacked Hong Kong with the intent on retrieving the seed. However his army was destroyed by the combined efforts of the Autobots and Dinobots and once Attinger and Lockdown were killed by Optimus, Galvatron retreated into Lockdown's ship, vowing to one day return and end Optimus claiming to have been "reborn".

Trivia

 * Galvatron becomes Pooh's enemy in Pooh's Adventures of Transformers the Movie
 * Galvatron will become the new enemy of Brian Griffin, Thomas, and Twilight Sparkle in Brian Griffin's Adventures of Transformers: Age of Extinction.
 * Galvatron will become the new enemy of Tino Tonitini in Weekenders Adventures of Transformers: Age of Extinction.
 * Galvatron will return in Weekenders in I, Robot.
 * Galvatron is voiced by Leonard Nimoy in the Transformers: The Movie, and by Frank Welker in Transformers: Generation 1.
 * Frank Welker also provided the voice of Galvatron in Transformers; Age of Extinction.
 * Megatron in the second live-action Transformers film was originally going to be named Galvatron after his resurrection. He kept his original name, however, to avoid any confusion.
 * However, he eventually named Galvatron in fourth movie, as he eventually gained powerful body thanks to humans whom uses his spark to make an artificial transformer that called Galvatron, effectively revive/evolve him in process much like Unicron did to Megatron in other versions.
 * Most incarnations of Galvatron are either white or purple with some exceptions.