Megatron is the primary antagonist of Transformers Prime, as well as one of the main characters in War for Cybertron and Fall of Cybertron. He was the leader of all the Decepticons during the Great War on Cybertron. During the Golden Age on Cybertron, Megatron was originally a mining bot designated D-16 before naming himself Megatronus, after the Prime of the same name. Megatronus was a gladiator in the pits of Kaon, who grew ambitious and saw corruption within the caste system and sought to put an end to it, with his own rule. Megatron began talking with his old friend, Orion Pax, who saw him as a mentor. After leaving the gladiatorial arena for the political one, Megatronus saw fit to shorten his name. When "Megatron" proposed his plans for a just society, he believed it was necessary to overthrow Sentinel Zeta Prime with force. But then Orion said it was not right to achieve justice with violence. When Megatron was rejected by the High Council, he waged war on Cybertron and left the planet wasted. Now he and his long story rival, Optimus Prime, battle on planet Earth for the control of both Cybertron and Earth.

During the Golden Age on Cybertron, "Megatronus" (which Megatron had named himself after Megatronus Prime), was bold, fearless, and a grandeur gladiator of Kaon among other Cybertronians. During the series, Megatron was scheming, fierce, egotistical, sadistic, and cruel. He was very manipulative and persuasive, as he was able to rally an army of Cybertronians to his cause and gain loyalty from several individuals, like Dreadwing. Megatron was mainly concerned with gaining power and would eliminate anyone who stood in his way, like Cylas, Airachnid, and Predaking. He also did not like to back down from a fight probably due to his time as a gladiator of Kaon. But he could be somewhat tolerant, as evidenced by his tolerance of Dreadwing's initial attempt to avenge his brother Skyquake but only to those who showed undying loyalty to him. He was also extremely prejudice, believing all life in the galaxy was second to the Cybertronians, particularly organics like humans. His only redeeming feature was that he never discrimateded against the different types of Cybertronians. He is a bot after the mold type of Megatronus Prime. He also had vowed to destroy his old foe, Optimus Prime, and his Autobot followers at any cost as they continued their war on Earth.

Megatron should sound like his voice actor, Frank Welker.

See the video link here for voice reference: https://youtu.be/Vm8iAHB6VkY?t=35s