The Decepticons are usually depicted as the antagonists in the fictional universes of the Transformers toyline and related comics and cartoons, and the enemies of the Autobots. The villains take many forms, and have many different origins and stories across the numerous different Transformers media, but in almost all incarnations, they are led by Megatron. They are typically represented by the purple facial insignia they all wear. Primarily, Decepticons have red eyes, while Autobots have blue eyes. They are usually known for their air power, especially since many of them turn into aircraft. They often turn into military vehicles, construction vehicles and even smaller-than-human-sized objects.
Most Decepticons think very little of humans and consider them no better than pests or "insects". This is strongly emphasized in the 2007 filmTransformers, when Megatron is seen flicking a human like a bug and saying "disgusting". Another example is when the Decepticon Frenzy complained about how the "stupid insects" tried to shoot him. In the animated series, Starscream works with the human, Doctor Arkeville and comments about how little he cares about destroying the entire planet Earth in order to achieve his goal.
In the Japanese version of the franchise, the Decepticons are called Destron or Deathtron (Japanese: デストロンDesutoron). The one exception to this naming convention is Car Robots, where the sub-group referred to as "Decepticons" in the Robots in Disguise adaptation, is known in Japan as the Combatrons (the Japanese name of the G1 subgroup known as the Combaticons). The overall name of the Robots in Disguise villain faction is Destronger. However, the Japanese Version of Transformers Animated uses Decepticon (ディセプティコン).
In the Marvel comic continuity, it was established that the Decepticons came in and out of the gladiator pits on Cybertron. Early on, the leadership of the Decepticons constantly changed due to their tendency to kill and replace their leaders. It would not be until a lowly Decepticon affiliated gladiator named Megatron assumed the throne that the Decepticons became a true threat to the rest of the population of Cybertron.
While Megatron was the primary leader, other Decepticons had prominent roles as leaders of the group. Shockwave, Scorponok, Bludgeon, and Ratbat all led the Decepticons, often overthrowing Megatron in the process or taking over the group during the period when Megatron was believed dead.
In the G2 Marvel series (which continues from the G1 Marvel series), it is stated that the Decepticon forces on Cybertron underwent a massive split in the wake of Megatron's disappearance when Megatron, Optimus Prime, and their respective troops crashed on Earth. The smartest, strongest, and most intelligent Decepticons left Cybertron to colonize nearby galaxies, leaving a token leadership of overly cruel and duplicitous Decepticons to control Cybertron. These Decepticons who left their homeworld became "The Second Generation" Decepticons, who were led by the villainous Liege Maximo. On the final page of the last issue, the Liege Maximo indicates that the Decepticons and all their descendants came from him, which indicates that he is the original founder of the Decepticons.
In the original animated series continuity, the Decepticons owe their warlike ways to their faction's origin as military hardware robots, created by the five-faced aliens, the Quintessons, while the Autobots were designed as consumer goods. Following the rebellion that forced the Quintessons off the planet, the Decepticons - as they named themselves - lusting for power, began a civil war. The Autobots could not hope to match the superior firepower and battlefield powers of the Decepticons, and instead turned to stealth, developing the art of transformation, modifying their bodies so that they could assume other forms. With this additional power, the Autobots were able to win the conflict, and a period of peace began, known as the Golden Age of Cybertron, when energy was plentiful and the planet shone with a golden hue.
Working in secret, the Decepticons also developed transformation technology, along with new robot-mode flight powers, and, under the command of one of the first of this new breed,Megatron, they attacked one of the capital's outer cities, killing the current Autobot leader. As the knowledge of this act was not made public, younger robots continued to idolize these powerful new flying robots - until one such young robot, Orion Pax, was duped by Megatron into allowing him access to an energy storage facility. Megatron turned on Pax and fatally injured him, but the ancient Autobot, Alpha Trion, then rebuilt Pax into the first of a new, battle-hardy breed of Autobot - now, he was Optimus Prime, leader of the Autobots, who led them against Megatron and the Decepticons as the civil war erupted once more.
After five million years, Cybertron was nearly depleted of all its energy when the Decepticons received word that the Autobots were planning to search for new energy resources. Following the Autobot ship, the Ark, in their ship, the Nemesis, the Decepticons boarded the Ark and engaged the Autobots on their ship. Unfortunately, the Ark drifted too close to Earth and crashed landed in a volcano. All the occupants of the Ark went into emergency stasis, while the Decepticons on the Nemesis ejected to South America. There, they scanned the forms of local insects, becoming the Insecticons. After 4 million years, the volcano the Ark was wedged in, erupted in Earth year 1984, restarting its computer, Teletraan I. Sending out Spy Satellites, Teletraan created alternative forms out of Earth vehicles for any transformers caught in its scanning beam (Like F-15 Eagles for Skywarp and a Semi-trailer truck for Optimus Prime). The Decepticons awakened first but later the Autobots did too, thanks to Starscream's carelessness.
By the Earth year 2005, however, the Decepticons had succeeded in completely conquering Cybertron, but the attack by Unicron, coupled with the temporary loss of Galvatron (a reconstructed Megatron) in that same year shattered their forces, allowing the Autobots to reclaim their home planet and rout their foes. The Decepticons fled to the planet Chaar, a world of ash and ruin, where they struggled to survive until Galvatron returned to them and reorganized them into a fighting force, battling to take back Cybertron.
The origins of the Decepticons in the IDW continuity would be explored in The Transformers: Megatron Origin, which confirmed Megatron as their founder in this timeline. On the run after an attack on an Autobot Senator after a mining dispute, Megatron stumbled onto underground gladiator games in the state of Kaon and quickly became one of its rising stars. However, it only truly became more than this when Ratbat, seeing an opportunity for profit, dispatched Soundwave to arm the gladiators. Megatron's forces then began to commit acts of terrorism increasing in scale and daring, attracting the attention of Sentinel Prime. Kidnapping Senator Decimus as a symbol (with the help of new airborne recruit Starscream) Megatron issued a rallying call to the gladiators and their supporter, promising to unite them under one badge and make the whole planet their arena. Prime's forces then found and arrested them en masse. This was all part of Megatron's plan: a supposedly informant Starscream massacred the Autobot Senate and freed the prisoners, signalling revolution and anarchy in Kaon. Megatron eventually killed Prime one-on-one as a symbol, and the Decepticons were forged.
In this continuity, there are a number of differences to the traditional norm. The Decepticons are no longer based on Cybertron due to its devastation by rogue scientist Thunderwing. Instead, they have spread out through the galaxy, using their transforming abilities to infiltrate target worlds (such as Earth or Nebulos) disguised as local vehicles and equipment. They then use their modes to create conflict, leading to complete anarchy as the world's political and social systems collapse. The Decepticons then move in and harvest the world's raw resources. How the world is pacified is unknown, although the The Transformers: Spotlight issue on Sixshot revealed he is often sent in to complete the destruction of entire worlds. As in other continuities, Megatron is in command, and thus far has had to deal with the rebellion of Starscream's Earth infiltration unit and the reemergence of Thunderwing, as well as moving on to Earth in order to harvest the extremely powerful Energon variant Ore-13, something which promises to give the Decepticons a significant edge over the Autobots.
In this continuity, the Decepticons were not the name of the evil faction, but rather a sub-faction created by Megatron. Realising that their ability to travel as Earth vehicles gave the Autobots an edge in stealth (whereas the Predacons mostly transformed into mechanical animals) Megatron decided to take drastic action.
Megatron recovered the protoforms of six Autobots that had crashed to Earth some time before looking for Fortress Maximus. Scanning them with vehicle modes at a military base and infusing them with a fraction of his spark energy to ensure their new loyalty, the first five became the Commandos. But when Megatron tried to scan a tanker truck as an alternate mode for the leader Scourge, Optimus Prime was scanned as well, resulting in much of Prime's personality being scanned as well. With an infusion of Megatron's spark energy to complete the concoction, Scourge was born, emerging from his pod as a dark twin of Optimus Prime, who proved that Megatron's programming had over-ridden any Autobot goodness within him. Appointed leader of the new "Decepticons", they quickly established themselves as a force to be reckoned with.
The newly created Decepticons would try many schemes over the course of the series, including attacking various dams and faking their defection to the Autobots. But their leader, Scourge, had grander ambitions in mind. The copy of Optimus' personality had been warped by Megatron's evil influence, but the individuality of Optimus remained and Scourge now wanted to control both Predacons and Decepticons. He would seize his chance when Fortress Maximus was awakened, directing him to destroy Galvatron (Megatron's new form). The attempt failed and Galvatron took a terrible revenge - he stripped the Decepticons of their individuality, turning them into little more than drones. After Galvatron's defeat by Omega Prime, the Decepticons were among those sent back to Cybertron for imprisonment, except for Sky-Byte.
The Decepticons appeared as mostly jets and military vehicles.
In the Unicron Trilogy continuity, the early history of the war is not expounded upon. The Decepticons, however, remain the main antagonists, with whom the Autobots have been warring for quite some time. The enslavement of the small, power-enhancing Mini-Cons has long been a major goal of the Decepticons, and the Mini-Cons are seen as key to winning the war.
Near the end of Armada, the Autobots and Decepticons join forces to defeat the planet-devouring Unicron, and the beginning of Energon sees them as uneasy allies. Many return to Megatron's side when he returns.
Cybertron sees a much smaller Decepticon force than the previous two series, and what has become of most of the survivors of the earlier series remains unknown. As Megatron's true plans are discovered, most of the Decepticons, unwilling to be sacrificed as pawns as their leader seeks to remake the universe, again battle a common foe alongside the Autobots. The end of the series sees three of the comic-relief characters, with a reluctant Thundercracker, desiring to begin a new Decepticon force, and take off in a makeshift rocket. It makes it as far as Mars before it crashes, as the ending credits montage of the final episode shows. The foursome survives, however. The fates of the other surviving Decepticons remains unknown, though evidence of Starscream's survival is discovered.
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. 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 is the true leader of the Decepticons, not Megatron. In the final battle in the second movie, there are many Decepticon casualties including Devestator (destroyed by a rail gun), Mixmaster (cut in half and his head stomped off by Jetfire), Rampage (killed by Bumblebee), Ravage (ripped in half by Bumblebee), Scrapper and Long Haul (killed by an airstrike), Scorponok (head crushed by Jetfire) and the Fallen himself who's 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.
In Transformers: Animated the Decepticons are usually bigger than the Autobots and usually turn into jets and military vehicles. It takes a group of Autobots to defeat one Decepticon and almost all Decepticons have red eyes and can fly. Most Decepticons in the series are similar to the original G1 series. In the Animated Series Blitzwing, for example, retains his triple changer modes of a tank and jet and also retains his G1 tan and purple color scheme.
This series depicts a Decepticon force that is far from what it apparently once was, with Megatron having been chasing the Allspark for millions of years prior to the series' beginning. The Decepticons have been "wandering the periphery" for some time, but have been driven off of Cybertron long ago. These Decepticons see themselves as 'freedom fighters,' seeking to throw off 'Autobot tyranny,' and their plans tend to revolve around returning to Cybertron with the means to retake it.
A series of stories printed by Fun Publications, set in a variety of continuities, the Decepticons of alternate worlds can vary greatly from the classics Decepticon image. In the Transtechstoryline the Autobots and Decepticons are merely political factions on a Cybertron which never broke out into war. Lines between good and evil are more blurred.
In the Shattered Glass storyline, a group of Decepticons, lead by Megatron, are the mirror images of the personalities of most Decepticons. In this world the Decepticon logo is red, and worn by heroic Transformers who seek to protect the weak and oppressed from the evil Autobots.