Megatron (aka Savage, Noble, Gnashteeth, Beast Megatron, Galavar and, um, Joe) began with one goal: restoring glory and power to the Predacon race, with himself at the helm. What distinguishes Megatron from the countless others who share this goal is his chutzpah. This is a guy who named himself after his faith's equivalent of the Antichrist. He is willing to risk everything—time, space, himself—if need be. He's willing to commit omnicide if it will further his goals. And there were times he would have won were it not for Optimus Primal.
Megatron is skillful at orchestrating vast schemes by manipulating others into doing them for him—an idle suggestion here, a conspicuously-planted object of interest there. He knows his enemies, and these include some minions, inside and out and exactly how to provoke them. He has no friends, only pawns, or occasionally, pawns that are too reliable to risk losing. Because of this attitude, this superiority complex, he despises working with the very troops he needs to carry out his plans. His hubris does not make him very popular, and so he must rely on power and fear to rule them. In fact, he prefers mindless drones.
Megatron is a gambler and can sometimes be a ham. (His manner of saying "Yesss..." is practically vaudevillian.) He has a twisted sense of humor and an overdeveloped sense of drama which rule everything he conceives, both long and short term. When he destroys you, he wants you to know that it was he who did this, and just how badly you were had. This is his greatest weakness. Like a Bond villain, he'll gladly boast to the hero at length about how smart and clever he was, giving his victim time to formulate a counterattack (he admits the Predacons sometimes gloat too much). He often sabotages himself by neglecting the quick and easy solutions for the bigger, meaner, and more complex.
He has a Rubber Ducky.
