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[[quoteright:350:[[ComicBook/TheTransformers http://static.tvtropes.org/pmwiki/pub/images/unicronnoms_7171.jpg]]]]
[[caption-width-right:350:Unicron, the Chaos-Bringer.]]

->''"Say goodbye to the universe, Maximals! Yes. The Autobots lose! Evil triumphs! And you... you no longer exist!"''
-->-- '''Megatron''', after trying to murder Optimus Prime and rewrite history, ''WesternAnimation/BeastWars'', "[[Recap/BeastWarsS2E13TheAgendaPart3 The Agenda, Part 3]]"

The LongRunner franchise Franchise/{{Transformers}} has numerous {{Complete Monster}}s.

* [[PhysicalGod Unicron]] is an ancient [[PlanetEater planet-eating]] Transformer that was created by a MadScientist called Primacron. Primacron created Unicron to help him take over the universe, but he rebelled and destroyed Primacron's lab. Unicron travelled through space and devoured many inhabited worlds, including the planet of Lithone. After learning of Optimus Prime's death and his passing of the Matrix of Leadership, Unicron tracked down Megatron and tasked him to destroy it, as it was the only thing that could stand in his way. Torturing Megatron into accepting his deal, Unicron reformatted him into Galvatron and made him more susceptible to his psychic assaults. Galvatron, tired of being Unicron's pawn, tried to use the Matrix to turn Unicron into his slave, but it had no effect in his hands. In retaliation, Unicron started [[OmnicidalManiac destroying Cybertron and attacked both Autobot and Decepticon alike]]. Unicron was eventually defeated by a Matrix-wielding Rodimus and only his head remained to orbit Cybertron, a testament to the [[GreaterScopeVillain Transformer]] that made even the mighty [[BigBad Megatron]] beg for mercy.
* [[TheAntichrist Megatronus Prime]] is known to all and sundry as [[FallenAngel The Fallen]]. If Unicron is the UltimateEvil, than The Fallen is [[{{Satan}} his Archangel Lucifer]]. Created by Primus as one of the original Thirteen Primes, [[FallenHero The Fallen]] became obsessed with the notions of [[OmnicidalManiac entropy and decay]], ultimately attempting to murder his creator after [[FaceHeelTurn betraying him]] to Unicron. Escaping the [[SealedEvilInACan prison he was trapped]] in some seven million years before the 21st century, The Fallen visited the G1 continuity, gathered several Decepticon outcasts and kidnapped four Transformers, through which he tried to channel enough energy to break the Seal of Primus, awaken Unicron, and end all reality, boasting that his victims were but "[[AGodAmI casualties in the wars of the Gods]]." Sharing his master's unquenchable thirst for destruction, [[TheDragon The Fallen]] is precisely the kind of servant that [[GodOfEvil Unicron]] most needs.

* [[BigBad Megatron]] is a self-proclaimed tyrant and would-be GalacticConqueror, who named himself after his world's equivalent of TheAntichrist. A [[BadBoss user and abuser of his followers]], Megatron divides the world into enemies and pawns, killing or enslaving the former, and ruthlessly exploiting the latter. A gloating sadist, Megatron never kills anyone quickly when prolonged torture will do, [[WeHaveReserves considers his own allies expendable]], and hopes to bring Cybertron, and eventually the galaxy, under his heel. His more notable crimes include extracting half of Rampage's spark, placing it in a vise, and using it to torture Rampage into submission; ordering Dinobot to kill Quickstrike, one of Megatron's (relatively) more loyal soldiers, after Quickstrike lost to Dinobot in a sort of re-entrance exam into the Predacons (Dinobot refused); an aborted genocide of humanity's common ancestor; attempting to rewrite all of his history by killing the original Optimus Prime; and finally, sacrificing all his remaining troops in order to gain control of the ''Nemesis'' and set out to overrun the galaxy. His defeat doesn't stop him either - when he returns in ''WesternAnimation/BeastMachines'' he's gotten worse, picking up a serious [[AGodAmI god complex]] along the way. Seizing control of Cybertron, Megatron [[YourSoulIsMine extracts the sparks]] from everyone on the planet, reducing them to [[SoullessShell mindless drones]]. Accquiring a hatred of all organic life, Megatron [[OmnicidalManiac tries to scrub Cybertron clean of it]], resulting in the near destruction of all life, robotic and organic, on his home planet when his last mad grasp for power finally fails.
* [[GiantSpider Tarantulas]] is Megatron's EvilGenius, and a schemer and [[ChronicBackstabbingDisorder backstabber]] second to none. Planted as TheMole in Megatron's operation by the Predacon SecretPolice, Tarantulas is a cackling MadScientist, who enjoys performing gruesome experiments on his victims, and [[VillainousGlutton eating anything or anyone]] he catches in his giant webs, organic or [[ImAHumanitarian robotic]]; he admits to enjoying the act itself more than the meal. He brainwashes several Maximal protoforms into becoming Predacons, most notably Blackarachnia and Inferno, and eventually reveals that he hopes to [[TheStarscream usurp control of the team]] from Megatron. That's all in season 1. Tarantulas later exploits and {{Mind Rape}}s Blackarachnia, leaving her with a paranoid terror of him, and later swears a vendetta against her, promising to [[DomesticAbuse hunt the other spider down and kill her for daring to defy him]]. He tries to destroy The Ark, which would have lead to [[OmnicidalManiac Unicron]] [[PlanetEater devouring]] Cybertron in the future, and the extinction of the Transformers as a species. Ultimately betraying both sides, Tarantulas is revealed as the spawn of [[UltimateEvil Unicron]], and attempts to use alien technology to wipe out Autobot, Decepticon, Predacon, and Maximal alike, swearing that when he's done with his own species, he will return and [[FinalSolution commit genocide]] against the aliens themselves. Void of loyalty or conscience, Tarantulas makes even [[EvenEvilHasStandards his own nominal allies uneasy]], a fact that he is [[CardCarryingVillain downright proud of]].

* [[PsychoForHire Lockdown]] is a ruthless and sadistic BountyHunter whose only loyalty is to himself. Unaligned with Autobots or Decepticons, Lockdown is indiscriminate in his prey, taking commissions from whomever is willing to pay him. To make himself more powerful, Lockdown steals upgrades from his targets, torturing them by cutting the weapons from his victims' bodies. Devoid of empathy, Lockdown sees his victims as little more than trophies, taunting them if he chances to encounter them again. [[APupilOfMineUntilHeTurnedToEvil Having once been a student of the Autobot Yoketron]], Lockdown murdered his former master in order to steal the protoforms under Yoketron's protection and sell them for his own profit. Merciless and consumed by {{greed}}, Lockdown is a [[TheSociopath sociopath]] who frightens and disgusts Autobots and Decepticons alike.
* Meltdown, originally Prometheus Black, is a human [[MadScientist scientist]] who ended up mutated by his own experiments. He tries to kill his rival, Isaac Sumdac, in a fit of rage whilst blaming him for all his problems (including [[NeverMyFault his self-inflicted transformation]]). Later, he becomes so obsessed with creating a human transformer, he not only mutates at least two innocent humans into [[TransformationHorror gruesome hybrids combined with animal parts]], he also decides to kidnap Sumdac's innocent [[WouldHurtAChild eight-year-old daughter]] as his newest test subject, deciding to experiment on children in general now. When Blackarachnia breaks him out of jail in exchange for him eliminating her organic half, [[UngratefulBastard he double-crosses her]] and tries to destroy her Transformer half - a deed which, if not destroying her soul completely, would have left her with a completely organic body she's disgusted with. He also forces the Dinobots to work for him by painfully burning them with his acidic touch until they follow his commands. He hurt them so badly, that they were willing to turn on Bulkhead and Prowl, their only friends among the main cast, just to stay in Meltdown's good graces.

* Colonel Leland "[[RightWingMilitiaFanatic Silas]]" Bishop is leader of MECH, a terrorist group researching cybertronian technology. In "[[Recap/TransformersPrimeS1E16OperationBreakdown Operation: Breakdown]]", he captures Breakdown, tortures him, tries to have him vivisected, and [[EyeScream removes one of his eyes]]. In "[[Recap/TransformersPrimeS1E17Crisscross Crisscross]]" he allies MECH with Airachnid to get his hands on another Cybertronian, Arcee and was perfectly willing to let Airachnid kill Jack Darby, a sixteen-year old teenager, and his mother to do it; he even states a few human lives are worth it for Arcee's tech. In "[[Recap/TransformersPrimeS2E19TheHumanFactor The Human Factor]]", after his men upload him into the [[spoiler:now-dead Breakdown's empty shell]], saving his life in the process, he thanks them for that and their years of loyal service by thanking them personally and then [[UngratefulBastard slaughtering them]]. He then, taking the name CYLAS ([[FunWithAcronyms "CYbernetic Lifeform Augmented by Symbiosis"]]), [[TranshumanTreachery betrays the human race to Megatron]], [[AGodAmI seeing himself as a superior being]], razing a military base just to get Megatron's attention, then attempting to blow up everybody inside Raf's house (the human trio, Agent Fowler and Raf's mother).
* The aforementioned [[EgomaniacHunter Airachnid]] is a self-styled "ex-Decepticon" who spent her time in the Great War capturing, torturing, and slowly killing any Autobots she could find. For certain victims, like Arcee, she'd go out of her way to find people they cared for and murder them before their eyes as part of her fun. After the war left Cybertron, she struck out solo to pursue a new hobby: hunting endangered (and soon to be extinct) species for sport and collecting grisly "trophies" of her kills. Should she find an attractive species that ''isn't'' endangered, she'll ensure that they are by the time she's done. After coming to Earth, she's decided to make humans her new toys, as Jack found out the hard way. Airachnid's not under orders or attempting any form of grand scheme, [[ForTheEvulz she just finds it fun]]. There's also the utterly brutal way she [[spoiler:kills Breakdown, tearing him into pieces]]. She's an unholy blend of Tarantulas, Beast Wars [[SerialKiller Rampage]], and [[PsychoForHire Lockdown]] pressed into a spider's shape and let loose on the universe.

* In the [[Franchise/TransformersAlignedUniverse Aligned Universe]], [[GreaterScopeVillain Megatronus]], once a member of the Thirteen Primes, was [[SealedEvilInACan locked away]] for betraying his comrades and murdering Solus Prime. [[LeakingCanOfEvil Still having influence outside of his prison]], Megatronus causes the Decepticon prison transport ship, ''The Alchemor'', to crash on Earth, unleashing dozens of Decepticons on the planet. Contacting [[BigBad Steeljaw]], Megatronus manipulates him into releasing him from his prison, and uses his psychic powers to force one of Steeljaw's soldiers to begin amputating his own arm to convince Steeljaw to work faster. When unleashed from his prison, Megatronus betrays Steeljaw, tries to murder both him and the Autobots attempting to thwart him, and reveals he plans to use the power of Unicron and the Allspark to [[OmnicidalManiac destroy both Earth and Cybertron in one fell swoop]] as revenge for his imprisonment. [[FaceHeelTurn Perhaps once a good person]], Megatronus shed any heroic traits and replaced them with pure [[TheSociopath sociopathy]] and blind hatred.

* [[OverarchingVillain Megatron]], later known as Galvatron, is the brutal commander of the Decepticons. While he was arguably a NobleDemon in ''[[Anime/TransformersArmada Armada]]'', and a lesser evil than [[GodOfEvil Unicron]], Megatron still committed a number of crimes in that series, such as enslaving Mini-Cons to use against the Autobots in his war of conquest, trying to kill the Autobots' human allies, murdering Smokescreen with the [[{{BFG}} Requiem Blaster]], and trying to [[EarthShatteringKaboom destroy Earth]] with the Hydra Cannon, only showing remorse when Optimus Prime sacrificed himself to prevent the final act. Upon his resurrection in ''[[Anime/TransformersEnergon Energon]]'', Megatron discards any redeeming features he once had in his quest for power and domination. Leading his forces in destructive raids for Energon, Megatron plans to use the element to revive Unicron and use him as a weapon. Now a callous ControlFreak, Megatron uses Unicron's power to [[BrainwashedAndCrazy subvert the wills]] of [[BadBoss his followers]], notably enslaving [[AntiVillain Scorponok]] and [[EmptyShell Starscream]] and trying to do the same to Inferno, torturing the Autobot to the brink of insanity. In ''[[Anime/TransformersCybertron Cybertron]]'', Megatron, having developed a [[AGodAmI god complex]], seeks to use the Cyber Planet Keys to accelerate the Unicron Singularity's expansion to [[OmnicidalManiac end reality]] and [[InTheirOwnImage reconstruct it in his own image]]. To this end, Megatron views his followers as utterly disposable, [[ManipulativeBastard cruelly manipulating them]], as well as several others, to serve his mad goals. Along the way, Megatron brutally guns down three Autobots, nearly killing them, to test his new weapon. In the end, when questioned on how his minions will survive his apocalyptic plan, Galvatron admits that he doesn't care if they do, proving himself to be a truly selfish monster. A power-hungry, uncaring, self-obsessed {{narcissist}}, Megatron demonstrates the worst that someone can sink to when [[ItsAllAboutMe they care only for themselves]].

* ''[[ComicBook/TheTransformersLastStandOfTheWreckers Last Stand of the Wreckers]]'': [[BigBad Overlord]] (who later returns in ''[[ComicBook/TheTransformersMoreThanMeetsTheEye More Than Meets the Eye]]'') is one of the most powerful Decepticons, but unlike the others, he just wants to kill anything and everything he can, in as many sick and twisted ways as possible. He horrifies all Cybertronians, Autobot and Decepticon alike, and Megatron was so wary of him that he had Shockwave alter his brain so that Overlord could never beat him. When he took over Garrus 9, he essentially turned it into a cross between a concentration camp and a gladiatorial arena, with torture, murder, and prisoners being forced to fight to the death for his own sick amusement.
* ''[[ComicBook/TheTransformersMoreThanMeetsTheEye More Than Meets the Eye]]'': [[AxCrazy Pharma]] is a former [[MadDoctor Autobot Medic]] who [[FaceHeelTurn went evil]]. After saving one of the main character's lives, he became the head medic at a medical facility on the planet Delphi. There he received death threats from an elite Decepticon unit who threatened to overrun the place, and [[WellIntentionedExtremist began bribing them with organs]], first from dead bots but later he began killing living ones. Eventually [[JumpingOffTheSlipperySlope it becomes too much]], and he has two other Decepticons unleash a plague on the facility to kill everyone and cover up his crimes. When he's revealed, he shoots a life-support, sending about 20 patients into near death states to distract everyone. He then tries to kill Ratchet twice before [[DisneyVillainDeath being thrown off the facility]]. He survives the fall and is recruited into Chief Justice Tyrest's group (who drilled a hole in his head and is trying to destroy all Transformers he considers inferior); all the Decepticons admit to being freaked out by him. When he finds Ratchet again, he separates Ratchet's head and spark from his body and starts torturing him. To prove he is a better medic, he has one of his co-workers from Delphi, Ambulon, [[HalfTheManHeUsedToBe sliced in half]], vertically from head to crotch, with a {{chainsaw|Good}}, and tells Ratchet to fix him. Ambulon dies in agony before the chainsaw leaves him. Later Pharma shoots Brainstorm.
* ''[[ComicBook/TransformersShatteredGlass Shattered Glass]]'': [[AxCrazy Ultra Magnus]] was locked up in his universe for trying to usurp Optimus Prime (and also got his face ripped off). He and several others travel to earth, where he assimilates numerous Autobots into the Junkion hordes (becoming mindless slaves and dead in all but name). After that, he proceeds to set up a plan to take rarified energon from Earth with his sword and destroy it. His plan is foiled when a shield is placed around the Earth, but his real plan was to [[OmnicidalManiac cause the death of the entire universe]]. Even the Normal Decepticons turned against him (They wanted to be the conquerors) and [[EvenEvilHasStandards were appalled]] when they realized the extent of the damage.

[[AC:[[Franchise/TransformersFilmSeries Live-Action Films]]]]
* ''[[Film/TransformersRevengeOfTheFallen Revenge of the Fallen]]'': [[SpellMyNameWithAThe The Fallen]], also known as [[SatanicArchetype Megatronus Prime]], is this film's BigBad and the film universe's first Decepticon. Originally one of the 7 members of the Dynasty of Primes, The Fallen betrayed his brothers and attempted to [[KillAllHumans use the Star Harvester on Earth's Sun]] regardless of the Dynasty's code against taking life, solely because of his FantasticRacism towards primitive humankind. Eons after his defeat, The Fallen corrupts Megatron, creates the Decepticons, and [[TheManBehindTheMan orders him to find the All Spark]], [[GreaterScopeVillain making him responsible]] for the events of the first film. After he lures Optimus Prime to his death using Sam as bait, The Fallen sank an aircraft carrier, attacked several human cities, and slaughtered a sizable military force while acquiring the Matrix of Leadership to activate the Star Harvester again, fully intending to [[OmnicidalManiac wipe out the human race]].
* ''[[Film/TransformersAgeOfExtinction Age of Extinction]]'': {{CIA}} agent Harold Attinger is the creator of "Cemetery Wind," a black-ops group taking it upon itself to wipe out all Transformers upon the planet regardless of faction, all out of nothing more than Attinger's FantasticRacism. Attinger entered a deal between himself, Lockdown, and Joshua Joyce's Kinetic Solutions Incorporated where Lockdown gives the remains of any Transformer he murders to Joyce for production into man-made Transformers, and Attinger would trade Optimus for the Seed needed to create more man-made Transformers to sell to the US Army. At first, Attinger may come across as a WellIntentionedExtremist, but given that he worked with Lockdown, wanted to create Transformers of his own, would have millions of innocents killed by The Seed, along with his own attempts to kill any humans who could get in his way (such as Tessa Yeager by proxy of his Dragon Savoy and Cade Yeager at his own hand) and ordering Savoy to murder witnesses of his presence in Hong Kong, it is clear Attinger is a {{hypocrite}} (if not merely a StrawHypocrite) out to [[{{greed}} get rich]].