Megatron

Megatron is the name of the main antagonist in the Transformers comics, and is the chief rival of the Autobot Commander, Optimus Prime.  The evil leader of the Decepticons is a Transformer, and has traditionally demonstrated the ability to transform himself from robot mode to a Walther P38 9mm pistol.

His most powerful weapon is his arm-mounted fusion cannon, which is capable of destroying a large amount of space. If connected to a black hole generator, Megatron's cannon produces anti-matter blasts that has the ability to destroy a small planet.  Such a configuration has the down side of leaving him in a weakened and vulnerable state.

He has had several different functions, including a strategic genius that plans from out of battle, to a courageous battle field commander. He is usually very intelligent though, and seems to be able to transform into almost any shape he desires. (He once became a look-a-like Starscream jet, and attached himself to the underside of Starscream.). Megatron started the great Cybertronian Civil War nine million years ago by attacking the city of Kaon with his brutal Decepticons. He then attacked Protihex only to be beaten by Sentinel Prime's Autobots, but the Decepticons raze Nova Cronum. Megatron then Kills Sentinel Prime and the matrix is passed onto a lowly records clerk named Optronix who then is transformed by it's power and becomes Optimus Prime and leads the Autobots. Then Megatron and Prime vanish 7.4 millions years ago due to an early space bridge experiment and are presumed dead. Then he reappears after an absence of one million years. Four million years ago Megatron does a sneak attack on the Autobot space ship the Ark which contained Optimus prime and the Autobots in his ship the nemesis the battle leads to both ships crashing and lying dormant until 1984 and is reconfigured into his present form.

Television

In his current appearance Megatron stars in transformers animated series where he has spent millions of years to use the Allspark to rule Cybertron in his attempt to retrieve it he explodes and is parts are on earth a boy discovers his head and in 50 years time that boy becomes the scientist Professor Sumdac who builds a robotic empire based on Megatron the Autobots who have become heroes in the city of Detroit soon discover that Megatron was kept and rebuilt in Sumdac's lab. He then made another attempt to retrieve the Allspark but failed and is now devising a way to conquer the planet Cybertron what his plan is exactly is unknown.

Movies:

Originally voiced by Frank Welker in the animated series and movie, Megatron was voiced by Hugo Weaving in the 2007 live action film.

2007 Movie: 

Megatron long ago went after the Allspark after it had been launched into space by the Autobots in an attempt to keep it away from him. He followed it all the way to Earth where he crashed into the North pole. His extreme heat from the journey and lack of energy caused him to go into stasis for millions of years. His body was discovered by an arctic expedition lead by Captain Archibald Witwicky and he was taken to a secret base under the Hoover Dam where his body was kept frozen. Decades later, the Decepticons came to Earth searching for the Allspark and Megatron was released from his frozen prison. Later, the Autobots and Decepticons had a battle for the Allspark at Mission City and, ultimately, Megatron was destroyed when Sam Witwicky plugged the Allspark into his spark and his dead body was dumped into the Laurentian Abyss along with the rest of the dead Decepticons.

Megatron as he appears in the 2007 film, Transformers.

Transformers: Revenge of the Fallen

The Decepticons steal a fragment of the Allspark and use it to revive Megatron. Megatron then flies to the crashed Nemesis ship and meets his master, the Fallen and tells him he failed to get the Allspark. He is then told that the Allspark is not gone, but rather has found a new container - Sam Witwicky - and that the only one that can defeat him is another Prime. Megatron goes to Earth and captures Sam Witwicky and with his Decepticons uncovers the symbols in Sam's head. Optimus Prime appears and rescues Sam and he and Megatron do battle in a forest and ultimately, Megatron kills Optimus Prime. Soon, Megatron meets his master once more and they go to Earth and use the symbols to find the location of the Sun Harvester - a giant machine capable of destroying suns to create Energon, the life-blood of all Transformers. However, as they prepare to activate the Sun Harvester, Optimus Prime is revived and combined with Jetfire's parts and destroys the machine, defeats Megatron, and kills the Fallen. Seeing his master die, Megatron listens to Starscream's plan to flee and says that it's not over yet.

Megatron's new form after being revived in Transformers: Revenge of the Fallen