The Decepticons make an appearance in the 2007 the Transformers live-action film. They include Megatron, Starscream, Frenzy, Blackout, Barricade, Scorponok, Brawl and Bonecrusher. The Movie Prequel comic by IDW Publishing would reveal their origins. Originally Optimus Prime and Megatron ruled Cybertron together, due to the power of the Allspark, a mysterious device that could give life to Transformers - and keep Cybertron itself alive. Eventually, Megatron began to desire its power for himself and assembled a like-minded army of separatists - the Decepticons. Megatron soon struck, and Cybertron became embroiled in civil war. This would later seem to be changed, however, by the sequel films, where it is revealed that Sentinel Prime was the leader of the Autobots and The Fallen the leader of the Decepticons when the war broke out. Optimus would only take command after Sentinel was seemingly killed in action and Megatron served as The Fallen's field commander due to the latter's incapacitation. The subsequent prequel novel Transformers: Ghosts of Yesterday revealed that Starscream seized command of the Decepticons after Megatron's disappearance.
Like the Autobots, the Decepticons are designed to look more organic in the movie. While the Autobots have a more human-like physiology, the Decepticons are more monstrous and insect-like in appearance. In Transformers: Revenge of the Fallen it is revealed that The Fallen, a Prime who turned evil, is the First leader and founder of the Decepticons, which would seem to imply the Decepticons were originally Autobots who turned evil. In the final battle in the second movie, there are many Decepticon casualties including Devastator (destroyed by a rail gun), Mixmaster (cut in half and his head stomped off by Jetfire), Rampage (killed by Bumblebee), Ravage (Stripped from his spine by Bumblebee), Scrapper and Long Haul (killed by an airstrike), Scorponok (head crushed by Jetfire) and the Fallen himself whose spark is ripped out and crushed by Optimus Prime. Also killed in the movie are Sideways and Demolisher, killed at the beginning by Optimus and Sideswipe. Megatron officially takes full command of the Decepticons at this point, swearing vengeance.
The Decepticons return in Transformers: Dark of the Moon with the plan to use a Space Bridge to bring an army to Earth and transport Cybertron into orbit to rebuild the planet with Earth's natural resources and human population as slaves. Megatron and Sentinel Prime planned this a long time ago, planning to meet on Earth before Megatron went after the Allspark and ended up frozen and the Ark was shot down by Decepticon fighters (few Decepticons knew of the plan) and crashed on Earth's Moon in 1961. This was detected by the Americans and the Russians and the space programs were created to reach the ship and study it. However, by 1963 the Decepticons had raided the Ark and removed all but five of the pillars and hid them on the Moon along with an army of hundreds of Decepticons, awaiting the time that the pillars would be used. After humans successfully reached the Moon and explored the ship, Soundwave and Laserbeak approached various humans including Dylan Gould's father to get them to shut down the American and Russian space programs. The Decepticons established a network of human collaborators who kept the humans from noticing the Decepticons actions on the Moon, later led by Dylan Gould. After a human collaborator named Alexi Voshkod leads NEST to Chernobyl where they retrieve an engine part from the Ark, the Decepticons reemerge for the first time since Egypt in the form of Shockwave and his Driller who attack, but retreat. This leads the Autobots to retrieve Sentinel and the remaining space bridge pillars and revive him and as this is going according to plan, Megatron orders Laserbeak to kill all the human collaborators but Dylan Gould which he does. Before he's killed, one of the collaborators named Jerry Wang alerts Sam Witwicky to this and he alerts NEST which ignores it. Sam and Seymour Simmons find out about the Decepticons plot from pictures a Russian probe got of the Decepticons hiding the pillars and the Dreads are sent to attack the convoy protecting Sentinel, but are killed by Bumblebee, Dino, Sideswipe and Ironhide. After Sentinel reveals his true colors and murders Ironhide, he sets up the pillars in the National Mall and brings the Decepticon army consisting of hundreds of Decepticon soldiers and Decepticon ships to Earth. With the army in hand, the Decepticons promise to bring no war against the human population in exchange that the Autobots must leave Earth. While taking off into the atmosphere, Starscream destroyed the ship, knowing that mankind will resist on their own. Some of the Decepticons scatter around the world to set up the pillars, but most of the army invades Chicago, devastating the human population and taking over. The Autobots, NEST and a team of mercenaries led by Sam Witwicky and Robert Epps invade Chicago and battle the Decepticon army, aided by the United States Army, and U.S. Air force. The group manages to take out much of the army including Laserbeak (killed by Sam Witwicky and Bumblebee), the Driller (killed by Optimus), Starscream (killed by Sam Witwicky), Soundwave (killed by Bumblebee), Barricade (killed by NEST) and Shockwave (killed by Optimus) and disrupt the Control Pillar, forcing Sentinel into battle. The combined human and Autobot forces overwhelmed Sentinel and his remaining forces and Tomahawk missiles destroy most of the Decepticon fighters causing Sentinel to flee before engaging Optimus one on one as Dylan Gould reactivates the space bridge. Sam Witwicky kills Gould and Bumblebee and Ratchet destroy the Control Pillar, causing Cybertron to implode and ruining the Decepticon plan. Also, the remaining Decepticon ships are sucked up into Cybertron by the space bridge and are presumably destroyed with the planet. Sentinel nearly kills Optimus, but Megatron, convinced by Carly Spencer that he would end up working for Sentinel, saves Optimus and incapacitates Sentinel. Megatron offers a truce between the Autobots and Decepticons after Cybertron is destroyed as long as he's in charge of the Decepticons again, but Optimus refuses and kills Megatron and Sentinel. While the loss of human life in Chicago is massive, the battle is a major victory for the Autobots as they eliminated most of the Decepticon army on Earth despite there being some still scattered around the globe and the entire Decepticon command structure was destroyed with all of its members killed in the battle.
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