His alternate mode is a laser pistol. In the film, he and the Decepticons tried to destroy Autobot City on Earth and all the Autobots, but the Autobots and Pooh and his friends fought valiantly to defend themselves. Optimus Prime came to Earth and battled Megatron to the death. Despite being wounded, Optimus gave one last punch to Megatron and Megatron was defeated and carried by Soundwave to retreat with the other Decepticons and fly on AstroTrain. On their way, back to Cybertron, AstroTrain ordered to "Jettison some weight" and Megatron and the other dead Decepticons were cast out of AstroTrain and found by Unicron and Unicron reformatted Megatron and turned him into Galvatron.
He is main antagonist of Transformers, and the secondary antagonist of Transformers: Revenge of the Fallen and Transformers: Dark of the Moon. As Galvatron, he is the secondary Transformer antagonist of Transformers: Age of Extinction.
Megatron was not always the viciously powerful and brutally direct leader of the Decepticons: he was once brothers-in-arms with Optimus and a student of Sentinel Prime, appointed to be Cybertron's Protector and commander of its Defense Force. But Megatron resented his comrade, knowing he was a Prime and therefore Sentinel's favored son. This anger allowed The Fallen to ensnare him and led to the revival of the Decepticons. Even without The Fallen though, it's not hard to imagine Megatron would have erupted Cybertron into war to rid himself of Optimus.
In the live action films
In the 2007 live action Transformers film, Megatron's alternate mode is a Cybertronian jet. He serves as the main antagonist of the first movie and secondary antagonist of the two sequels. The apparent explanation for the departure from his gun form is that director Michael Bay does not want to include any sort of size changing in the transformations, which the writers described as "cheating". (This significant change in size is known in Transformers fan communities as "mass shifting" & "mass displacement".) In one of the special features on the DVD, G1 Megatron's transformation was likened to Darth Vader turning into his own lightsaber to be wielded by someone else. Additionally, Bay states in the DVD that Megatron's face was originally different from the one shown in the film, but he asked it to be redesigned due to fans reacting with strong opposition to it once Megatron's design was unveiled before the film was completed.In the second film, Megatron gains a different alternate mode, that of a flying Cybertronian tank. In the third film, Megatron receives another different alternate mode, that being a Mack 10-wheeler tanker truck (a demented version of Optimus Prime's alternate mode) with a tarp which may act as a cowl to partially hide Megatron's face due to extensive damage he received in the second film.
Actor Hugo Weaving provides the voice of Megatron in the films. His voice in the series seems to have been modulated to give it a deeper, growling tone as well as the other voice actors. The original voice of Megatron, Frank Welker, provides his voice for the official video games of the movies (with Dark of the Moon as the exception, where he was voiced by Fred Tatasciore), along with the exclusive animated prequel.
Like all characters in the film, Megatron was redesigned for purposes of realism and focus on the alien aspect of the Transformer race. However, he still retains some minor aspects of his Generation 1 design. As shown in the film, he can transform his right hand into a gun, combine both of his arms to form his iconic fusion cannon, and can transform his right arm into a steel flail. In the second film, after Megatron's resurrection, his right arm can transform into the fusion cannon in its entirety, coupled with a lobster claw-like blade/crushing device. In the third film, Instead of using a fusion cannon integrated into his arm, he uses a handheld version of it, which resembles a human shotgun, specifically a Lupara.
Megatron is the secondary (robot) antagonist of Age of Extinction, and is now known as Galvatron.
Unknown to all, Megatron's mind actually survived his destruction and was in a state of dormance inside his severed head. A few years after the battle of Chicago, KSI salvaged Megatron's remains, where CEO Joshua Joyce had them use it to create a new Transformer that intended to resemble Optimus Prime. However, unknown to any of the humans, their tampering re-activated Megatron's spark within, and he began to influence the humans to create and entire army of Transformers so he would eventually hack them and rebuild his Decepticon army. He also learned of an ancient Cybertronian weapon called a "seed" which could cyberform an entire city on it's own which he desired to replicate into more but found himself under humans' control and renamed Galvatron.
Humans' control over himself didn't last long, however, as Megatron later freed himself permanently, but not before he reformated the other fifty artificial Transformers in KSI's facility in China so they became his new army. However, the new Decepticon army was destroyed and Galvatron was forced to retreat with his remaining minions. He took over Lockdown's spaceship, and claimed that he and Optimus will meet again one day.
In other movies and projects
Megatron has returned in many other movies or projects.
Megatron first appears in Thomas, Twilight, and The Mummy Returns. [along with Starscream] Seeking to get revenge, and main goal is to kill Princess Celestia. After our heroes make it to the Pyramind of the Scorpion King, he attempts to kill Celestia with his Fusion Shotgun. But then Thomas drives in front of the blast at the last second, and is killed instead. Then in the pyramind, Optimus, Celestia, Percy, Shining Armor, Cadance, and Twilight battle Megatron, Starscream, and Queen Chrysalis. Then after the Scorpion King is killed, Celestia uses the Blue Ruby and the Black Pearl to increase her power and she kills Megatron. [by firing a blast of magic into his spark]
- Despite his hatred for humans, Megatron is the only Decepticon who fluently speak English instead of Cybertronian, which almost all other Decepticons do at the beginning of the first film.
- Megatron scans and transforms into a trucker in the third film in order to blend into the human's every day lives. This can notably be compared to Optimus's trucker vehicle mode.
- Megatron in the first three films is voiced by Hugo Weaving, who also played Agent Smith from The Matrix franchise, and Red Skull from Captain America: The First Avenger.
- As Galvatron, he is voiced by Frank Welker, who also voiced Megatron's original incarnation as well in the video game adaptations of the film series. And Frank return to voice Megatron in The Last Knight.
- In the second film's old script, Megatron was promised to become a Prime by the Fallen only to be betrayed, as Optimus states primes are born, not made. Megatron then wipes himself off the radar where he goes back to the Nemesis and raises his hatchlings, enraged. This conclusion was instead used in the Decepticon campaign of the Revenge of the Fallen console games. However, it is slightly altered as, after the Fallen's betrayal, Megatron murders the Fallen himself before nurturing his hatchlings.
- Megatron was originally going to named Galvatron after his resurrection in the second film, but he eventually retained his original name to avoid confusion.
- Galvatron, however, appeared in Age of Extinction, where he appears as a human-made Decepticon designed by Joshua Joyce whom made from Megatron's remains. This practically explain why Joshua ended up revived him in a new body like his other incarnation whom evolved/revived with Unicron's influence.
- There were originally going to be scenes and mentions of Megatron actually eating the sparks (hearts) of his fallen foes, but was cut for time issues. He also apparently injests the innards of his enemies in the DS version of the game and such an action was performed by him in a book based on the first film.
- Elements from Megatron's appearance, especially in the first movie while his alt-mode is a cybertronian jet, are added into his Transformers Prime version.
- As Galvatron, he bears more resemblance to Nemesis Prime than most of his incarnations, as both robot villains are evil "clones" of Optimus Prime.
- Megatron will be come Thomas and Twilight's enemy in Thomas and Twilight Sparkle's adventures of Transformers, and then will try to kill Twilight and the rest of the Mane Six and then knocks Thomas and Twilight unconious in Thomas and Twilight Sparkle's Adventures of Transformers Revenge of the Fallen, and return again in Thomas and Twilight Sparkle's Adventures of Transformers Dark of the Moon.
- Megatron will be come Tino's enemy in Weekenders Adventures of Transformers, and then will try to kill Chris, Yoshino and Yoshinon in Weekenders Adventures of Transformers: Revenge of the Fallen, and return again in Weekenders Adventures of Transformers: Dark of the Moon.
- Megatron returns seeking revenge on Thomas, Twilight, and the others in Thomas, Twilight, and The Mummy Returns and he plots to terminate Princess Celestia.