Megatron is the name of multiple ruthless leaders of the Decepticon faction in many Transformers continuities. All the Megatron characters have things in common, from their creation of new rebellious factions, to their hatred of the Autobot and Maximal factions. Many Megatrons wield "Fusion Cannon" weapons that can blast Autobots into oblivion with concentrated blasts of most commonly purple energy.
There are many bearers of the name "Megatron" over the course of history and they have taken modes that are wildly varying such as pistols, helicopters, tanks, and dragons. Megatron is a name that has struck fear into many groups, from Optimus Primal's brave group of Maximals, to the veterans of the Autobot Elite Guard. - The Predacon Megatron aboard the Nemesis. '" The name Megatron once brought terror across the galaxy and shall do so again!"'