Megatron is a character from the Transformers franchise created by American toy company Hasbro in 1984, based on a design by Japanese toy company Takara. The original Megatron was the leader and warlord of the Decepticons, a fictional faction of sentient self-configuring modular extraterrestrial robotic lifeforms from the planet Cybertron. He serves as nemesis of the Autobot leader Optimus Prime.
Megatron is usually depicted as having risen up from the lowly worker to become a champion in gladiatorial combat. As a gladiator, he took the legendary name "Megatronus" as his own and would similarly inspire a later villainous character. He became an activist, trying to reform the Cybertron's corrupted governing body and an end its unfair caste system. He mentored the young Orion Pax, and together they championed the downtrodden and preached that freedom of self-determination was the right of all sentient beings. Orion Pax would later become Optimus Prime and utilize Megatron's teachings against him when he became corrupt.
Megatron could transform into three different types of guns; a Walther P38 handgun, a particle beam cannon, and a telescopic laser cannon. He has the ability to transform between his robot shape and various weapons or vehicles, but these "alternate-modes", his origins and even personality, can vary depending on which "universe" he's depicted in. This origin is considered the most consistent between the various incarnations.