Megatron is a fictional character from the various Transformers universes, being the leader of the evil Decepticons and the primary antagonist of the series. Wizard Magazine rated him the 68th greatest villain of all time.Wizard #177
Transformers: Generation 1
Megatron is a Transformer robot, the original "alternate mode" being a custom Walther P38.Megatron is an iconic Transformer alongside his rival, Optimus Prime, primarily because of his large exposure in the comics and television series as well as his function as the leader of the villainous Decepticons, opposite the heroic Autobots.Bob Budiansky, the writer for the Marvel Comics series stated in an interview that the name "Megatron" is a portmanteau derived from "Megaton" and "Electronic." Originally Hasbro took issue with the name, saying it sounded too dangerous, like an atomic bomb. Budiansky responded that as the lead villain, that was the whole point. Hasbro saw his reasoning, and approved the name. http://www.alteredstat
Source:
http://en.wikipedia.org/wiki/Megatron