Megatron was the Leader of the evil Decepticons and arch enemy of Optimus Prime. He turns into a cybetronian tank and a cybertronian plane. He is armed with a fusion cannon and was infused with the evil Dark energon that makes decepticons more stronger, faster and increase strength and defense but makes them more aggressive and evil while it makes Autobots sick and weaken them thus only Autobot doctors and medics can cure and deal with it. Megatron often beats up Starscream for his failures and his insubordination. One time when Optimus Prime lost his memories and the wisdom of the Primes he was tricked into becoming Megatrons friend and thinking he is Orion Pax thus he took him back to his ship the Nemesis but Optimus Prime later rebels against Megatron and got his memories back thus making the two enemies once more. Megatron later replaced Starscream with Dreadwing as his second in command. Megatron was killed by Prime but returns as a Ghost made out of Dark Energon. He haunts a planet full of dead stuff and he tries to use his dark energon powers to send endless waves of zombies to destroy the local autobots but failed and thus failed to get his revenge.
Megatrons body is basically a dead ghost version of Megatron in transformers prime.