%% '''Note: Due to the controversial nature of this trope, any changes (additions, removals, edits) should be discussed [[http://tvtropes.org/pmwiki/posts.php?discussion=6vic3f9h1cy5qivsenw8llok here]].'''
%% Please read the discussion page first to see if your example or removal has already been brought up.
%% Image selected per Image Pickin' http://tvtropes.org/pmwiki/posts.php?discussion=1516305195091564800
%% Please do not replace or remove without starting a new thread.
[[quoteright:350: [[Series/KamenRiderAmazons http://static.tvtropes.org/pmwiki/pub/images/sojishitashimobeating1.jpg]]]]
[[caption-width-right:350:"Just getting ready to exercise."]]

-> ''"He is a monster, far worse than the Roidmudes you despise. The marathon of torture that man inflicted upon me...It has been burned into my memory...''"
-->--'''Heart''', on '''Professor Tenjuro Banno''', to Banno's son Go(u) Shijima, ''Series/KamenRiderDrive'', "[[Recap/KamenRiderDriveEp40WhyAreTheTwoScientistsInAConflict Why Are the Two Scientists in a Conflict?]]"

''Franchise/KamenRider'' has been [[LongRunner around since 1971]], with its main theme being about how someone can rise above tragedy to become a hero. While many villains have redeeming qualities, these are [[CompleteMonster these very worst]] that have none.

[[AC: Franchise-Wide]]
* [[ANaziByAnyOtherName The Great Leader of Shocker]] [[labelnote:Also Known As]] [[IHaveManyNames The Great Leader of Gel-Shocker, The Great Leader of Destron, Great Leader of Black Satan, Great Leader of Delza Army, Great Leader of Neo-Shocker and the Generalissimo of Badan]][[/labelnote]] serves as the OverarchingVillain of the Showa era and an archetype to many of his successors of the Henshin genre. Desiring to rule the world, he kidnaps countless innocents to experiment on and brainwashes them into becoming his soldiers, even [[ElectricTorture torturing them with electricity]] to test them. When his organization Shocker would start to falter by the efforts of the heroes, he founded Gel-Shocker, slaughtering all of his soldiers in retribution for their failures. He then resurfaced in ''[[Series/KamenRiderV3 V3]]'', where he would create the organization Destron and attempted to launch Operation: Japan Annihilation, which would release DeadlyGas across the entire country and take the lives of millions; he even attempted to throw his own son in a pool of acid for defying him. He resurfaced again in ''[[Series/KamenRiderSkyrider Skyrider]]'', where he manipulates the Neo-Shocker group to gain more power, attempting to wipe out the world's oxygen and exterminate humanity to spite the Riders. In the movie ''Film/OOODenOAllRidersLetsGoKamenRiders'', he resurfaces as the final villain to use time travel to conquer the world, even murdering his own generals to achieve victory, believing in achieving power for himself no matter what the cost. Defined by his [[AGodAmI God Complex]] and desire to [[InTheirOwnImage remake the world in his own image]], he represents the very worst the franchise has to offer.

''[[AC: Series/KamenRider]]''
* [[InsaneAdmiral Colonel Bakarashin Iinodevitch Zol]] serves as TheDragon to the Great Leader. After serving as a [[ThoseWackyNazis Nazi officer]] in UsefulNotes/WorldWarII, Zol joins Shocker where he gains a reputation for wreaking havoc in the Middle East. He quickly lives up to this reputation when heís transferred to Japan to deal with Kamen Rider 2. He fails to show any sense of shame for his crimes, ranging from [[MindRape brainwashing children]] into becoming Shocker guerilla soldiers to using Wolfsbane to gas attack Goroís town. Colonel Zol is also a [[BadBoss horrible boss to his men]], as shown when he praises a revived Egyptus, a mummy kaijin that can incinerate victims, for testing his abilities on--and ultimately killing--one of his mooks. The sequel series ''Series/KamenRiderV3'' only adds to his crimes. Together with Doctor G, a revived Zol plans to initiate Operation: Japan Annihilation, which involves unleashing a [[DeadlyGas toxic gas]] in Hokkaido to kill innocents. Zol also does not care about fellow Shocker and Destron officers at all, as seen when he tries to have fellow Destron officer Ambassador Hell executed for failing to defeat Kamen Rider V3. Zol stands out even to this day as one of the very worst the franchise ever produced.

* Marshal Armor, AKA Zariganna, is the fourth and final Destron Commander. When he assumes command of Destron, his first act is to plant evidence against their head scientist, Jo(u)ji Yuki, whom he views as a threat, and execute him via acid pit. Knowing the man values his hands for his work, Armor begins the execution by burning one off first. From there, Armor launches a number of deadly schemes, including attempting to cover Tokyo in [[DeadlyGas nerve gas]], kidnapping children for slave labor, and [[WouldHurtAChild unleashing Vampire-Chameleon on more children]] to feed off their blood. When Vampire-Chameleon kills a pair of his own men, Armor coldly remarks that [[LackOfEmpathy if they weren't so weak they wouldn't have died]]. When ordered by the Destron Leader to [[NukeEm launch a nuclear assault on Tokyo]], Armor kidnaps a scientist's family to force him to work on the weapon. When he frees the heroes, Armor has him killed, and hangs his corpse outside the Destron base as a warning to all who would defy him.

* [[MultipleHeadCase Ten-Faced Demon Gorgos]] is the leader of Geddon and a brutal sadist with a taste for human blood--[[LifeDrinker which gives him power]]--and giving ironic deaths to [[BadBoss his own men]]. A [[DiscOneFinalBoss subordinate]] to Ruler, Gorgos is [[EstablishingCharacterMoment introduced]] pouring incendiary blood over the Amazon rainforest, burning a tribe alive and wounding [[TheHero Daisuke Yamamoto]]. In his mission to defeat Daisuke and obtain his bracelet, Gorgos punishes those who dare to fail him, through such means as burning; consumption by vampire bats; and exposure to the sun. Gorgos makes sure to ruin Daisuke's life by killing people close to him, and laughing at their deaths. In one occasion, Gorgos discovered that Daisuke was a close friend to a little girl, and he had her father EatenAlive by a giant snake. After kidnapping several students from an elementary school, Gorgos has them [[WouldHurtAChild tied to the ceiling and tortured with hot gas]]. Growing bored of drinking men's blood, Gorgos uses his servants to try and capture young women, and later children, for him to drain their blood. Capturing a human criminal, Gorgos turns him into the Ant Beastman, praising him for his violence even after he had attacked his own allies. Before his ultimate defeat, Gorgos invaded a local university and slaughtered multiple people with acid.

''[[AC: Series/KamenRiderKuuga]]'': While the Gurongi Tribe is a race of {{Serial Killer}}s, two of them stand out as among the worst of their kind:
* [[AxCrazy N-Daguva-Zeba]] is the [[BigBad lord of the Gurongi]] and the Ur-CM of the Heisei era. A sadistic BloodKnight who [[TheSocialDarwinist absolutely despises the lowly and weak]], Daguva doesnít care about any human or Gurongi lives, and is willing to use any means necessary to make humanity as violent and hateful as he. Upon being reawaked from Kuugaís sarcophagus, he releases the 200 Gurongi and murders the archaeologists, thereby kicking off the series. After his escape, he restarts the Gegeru (which involves the Gurongi [[HuntingTheMostDangerousGame hunting humans]] as part of a game) and kills 152 of his own kind in Nagano. He then reveals himself to the public by killing [[spoiler:Zu-Gooma-Gu]] for using his armor before resurfacing under the guise of a [[TeensAreMonsters white-suited teenager with an aura]] as he unleashes heavy rain in Japan. After Yusuke Godai (Kamen Rider Kuuga) defeats [[spoiler:Gadoru]], Daguva ambushes Kuuga, [[NoHoldsBarredBeatdown mercilessly beats him up]], and incinerates numerous people in his wake as he leaves Yusuke behind. After continuing his systematic genocide and attempting to bring about the "Ultimate Darkness" to turn humans just as violent and twisted as he is,[[spoiler:he meets Yusuke in Mount Kuro where they have their final fight. There, Daguva finally dies, laughing to the very end hoping that Yusuke would be corrupted by violent hatred.]]
* Years after he blighted television screens in Japan, Go-Jaraji-Da (the Porcupine Gurongi) still stands as the standard to which other [[MonsterOfTheWeek kaijin-of-the-week]] in ''Franchise/KamenRider'' are compared to. Jaraji uses his upper-class privileges to choose the 90 teenage boys in Midorikawa High School's 10th grade as his targets for his game. Using super speed and poisonous darts that kills his victims from encephalitis within four days, Jaraji terrorizes and poisons all but one of his targets, condemning many of his victims to slow, brutal deaths and drives others to suicide. As those who commit suicide do not count to his Gegeru, Jaraji compensates by killing high-school boys belonging to other grades and numerous policemen. Most of the other Gurongi are either required to participate in the Gegeru or [[PunchClockVillain merely see the Gegeru as a necessary duty]]. Jaraji, on the other hand, commits his crimes precisely because he enjoys himself watching living beings suffer and coldly admits this to a family before closing in on one of his targets. It's no wonder [[FriendToAllChildren Yusuke Godai]] snapped and [[NoHoldsBarredBeatdown killed Jaraji]] [[TheresNoKillLikeOverkill so savagely]].

''[[AC: Series/KamenRiderRyuki]]'': In this battle of where ThereCanBeOnlyOne, these Riders stand out as particularly vile:
* [[KnightOfCerebus Takeshi Asakura]]/[[BloodKnight Kamen Rider Ouja]] is the archetype evil rider of the Heisei era and a psychopath that is drawn to violence and wishes to perpetuate it. Originally a vicious serial killer after gaining his Rider powers via Shiro Kanzaki, he would rack up the highest body count amongst the Riders, who are pitted in a battle to the death where ThereCanBeOnlyOne. A vicious sadist, he's also responsible for the murder of an innocent woman, who turns out to be [[spoiler:Kamen Rider Femme's sister, thus making getting revenge her reason for entering into the Rider Battle]] and later uses an innocent child as monster bait with him willing to let her be killed to fuel his thrill for carnage. To top it all off, he kills [[spoiler:his own estranged brother]] by feeding the latter to his [[{{Mons}} Contract Monster]], Venosnaker...after revealing that ''he'' was the one who set the fire which [[spoiler:burned down their home, killed their parents, and separated them during their childhood in the first place]].
* [[StarterVillain Masashi Sudoh /Kamen Rider Scissors]] is a [[DirtyCop detective who uses his position to cover up his illegal acts]]. Asked for a larger share of the profits by his partner, Sudoh kills him and plasters him into the wall of his own shop to hide the evidence. When Shiro Kanzaki offers him an Advent Deck, Sudoh agrees in order to use the Contract Monster he's given, Volcancer, to feed it anyone who knows of his crimes, doing so to countless people who've come too close. He later attempts to kill a reporter inspecting his shop and Shinji Kido after he offers peace, along with anyone close to him to keep them quiet and hold Yui hostage from Shiro. With his crimes discovered, Sudoh follows it up by feeding two cops attempting to arrest him to Volcancer before he succumbs to the same fate as them. In spite of having little screentime, Sudoh was the first demonstration that some Riders were selfish people with only their own interests in mind, willing to stoop to absolute lows.

''[[AC:Series/KamenRiderFaiz]]'' [[AC:(555)]]:
* ''Seiden: Grotesque/Deformed Flowers'': In this non-canon novel adaptation by Creator/ToshikiInoue, [[StalkerWithACrush Masato Kusaka]][=/=][[HumansAreTheRealMonsters Kamen Rider Kaixa]] manages to be [[AdaptationalVillainy much more repugnant and heinous]] than he already was in the show. In the past, Kusaka was one of the "Ryusei Children", orphans raised to be able to successfully wear the drivers. Bullied by his peers, Kusaka had Mari to keep him company, but unbeknownst to her, Kusaka only saw her as a possession, rather than a real friend. When his classmates are attacked by an Orphnoch, Kusaka [[FantasticRacism generalized the entire race]] as being monstrous abominations who deserve to be destroyed by him, even if there are good-hearted Orphnochs. Upon getting hold of the Kaixa Gear, Kusaka took the chance to try and [[FinalSolution kill all Orphnochs]] and keep Mari only to himself. Kusaka was responsible for the murder of Yuka, another bullying victim and a close friend to [[BigBad Kiba]], driving him to hate the human race. After killing several innocent people, Kusaka rapes Mari, not caring if the assault had left her hopeless and depressed. Kiba is [[RapeIsASpecialKindOfEvil so disgusted]] by this that he personally [[AnArmAndALeg rips off Kusaka's limbs]] as punishment for his crime. Later, Kusaka resurfaced once again to make Mari's life a living hell, but was ultimately stopped and killed by [[TheHero Takumi Inui]]. A calculating, antisocial bigot who saw others as mere objects for him to use in his genocidal quest, Kusaka served as a brutal example of how even the worst kinds of people can become Riders.

''[[AC:Series/KamenRiderBlade]]'': In the battle royale to become the dominant species, many competitors had good qualities, but these two only care about themselves and crossed the ultimate line in an attempt to achieve victory:
* [[AGodAmI Hiroshi Tennoji]] serves as the series' true BigBad and absolutely reeks of [[ItsAllAboutMe obsession for self-preservation]] and world domination by any means necessary. As the head of BOARD, he creates the Battle Fight by releasing the Undead and manipulating his contracted Kamen Riders to take them out. As the battle progressed, he invented the Trials and the Titan Undead, all so he could buy himself time to create Kerberos, an artificial Undead with DNA from all 53 Undead that could surpass the Black Joker itself. Tennoji's invention kills the entire BOARD staff upon being born from the Stone of Sealing before he seals the artificial Undead to create a new Change Card. He uses the card to transform into Kerberos II before revealing his dream: [[TheCaligula to create a new world order with himself as its ruler]]. Wishing to [[InTheirOwnImage remake the world under him]], his actions would produce countless tragedies throughout the series.
* [[PoisonousFriend Isaka]]/[[AgentPeacock Peacock Undead]] exemplifies how low [[ManipulativeBastard manipulative bastards]] can go. As the first Category Jack Undead, he designed Rider System 3, a belt that allows the user to transform into Kamen Rider Leangle. Unfortunately, that same belt requires using an improperly sealed Ace card that contains the Spider Undead, meaning that its user would be mentally enslaved by the Undead (as later seen with Mutsuki). After designing the corrupted Rider System, he brainwashed many people that he was going to use as expendable slaves to create his "Ultimate Rider". When this plan failed, Isaka turns his attention to Sakuya Tachibana and attempts to retrieve him as a prototype user. Isaka knows about Tachibana's subconscious fear and takes advantage of it to [[CurbStompBattle curbstomp]] him. Isaka tricks his defeated opponent to getting addicted to [[FantasticDrug Schuld Ketsner seaweed]], lying that the aggression-inducing plant would eliminate fear. [[spoiler:When Tachibana's girlfriend Sayoko notices her lover's addiction, Isaka smugly kills her for attempting to clean up her lover.]]

''[[AC: Series/KamenRiderKiva]]'': While the [[OurVampiresAreDifferent Fangire race]] are the major antagonists in the series, there are 3 specific members who crossed the ultimate lines:
* [[BigBad The Bat Fangire]], more commonly known as the [[VampireMonarch 1986 King]], is a ruthless tyrant who fails to understand the concept of love. As the original lord of all Fangires, the King uses his position to annihilate the Merman and Franken races, as well as persecute [[LastOfHisKind Jiro, the last Wolfen]]. When he finds out that his wife Maya has fallen in love with Otoya Kurenai, he tries to force her to kill him with the logic that if he kills her for her infidelity it would mean he actually cared for her, so this is much better. When she does not go through with it, the King offers Jiro, as well as the sole surviving Merman and Franken, a chance to avoid extermination in exchange for killing Otoya. When they choose to escape instead, the King forcibly transforms them into {{Empathic Weapon}}s. He then kidnaps Otoya and attempts to use his life energy to feed Castle Doran, the King's living castle. When Otoya escapes, the King exposes his lack of any sense of love toward his own wife by threatening the life of [[OffingTheOffspring their own infant son]] as blackmail to prevent her from seeing Otoya again. This [[EvenEvilHasStandards disgusts Kivat-bat the 2nd]], who is meant to be the King's loyal TransformationTrinket, so much that he offers Otoya a chance to become Kamen Rider Dark Kiva in order to destroy the King.
* The Lion Fangire, also known as Rook, is an AxCrazy, merciless, and [[ArsonMurderAndJaywalking easily bored]] {{Sociopath}} who treats the lives of humans and monsters alike as a game. Twenty years before Wataru becomes Kamen Rider Kiva, Rook murdered Yuri Aso's mother so traumatically that Yuri swore vengeance on all Fangires (including Wataru's mother Maya). He also was single-handedly responsible for driving the Wolfen race to near-extinction, leaving Jiro as the sole survivor of his genocidal rampage. As the flashbacks progress, Rook devises his personal game to combat boredom called the "Time Play," in which he hunts and eats a select group of people within a time limit. If he succeeds in killing the intended number of people, he rewards himself with ice cream; fail and he self-punishes himself with electric shocks. His already suspect sanity gets even worse when he reawakens and regains his memories in 2008. He proposes a new game which would have him do good deeds before getting himself killed not out of a change of heart but from boredom from constantly playing the "Time Play" game.
* The Rhino Fangire was rather nasty. He tricks young people into believing he'll help make their dreams come true to lure them in so he can steal their life force. After killing them, he takes an item from them that relates to their dream as a trophy to put in his "Dream Graveyard". His choice of prey is based solely on a love for crushing the dreams of young people and nothing else. Even [[TheHero Wataru]], who had generally tried to find the good in everyone, even Fangires, found his actions unforgivable.

''[[AC: Series/KamenRiderDouble]]''
* [[MorallyAmbiguousDoctorate Doctor Shinkuro Isaka]], the [[ElementalPowers Weather Dopant]], killed Terui's family, modifies Gaia Memories to kill their users so that he can take their power for himself, and is able to use Gaia Memories via direct insertion without any ill effects (typically, repeated use of Gaia Memories via direct insertion warps the user's mind, which shows that Isaka didn't have far to fall). He then tries to get Saeko to kill her own father and take control of the Museum.
* ''W Returns: Eternal'': [[MorallyAmbiguousDoctorate Dr. Prospect]]/[[BigBad Eyes Dopant]] is a man who kidnapped people from all over the world to make them into, in his own words, "lab rats" for his Quark Project by giving them PsychicPowers. When he arrives on the scene, every one of these people with psychic powers are utterly terrified of him, showing how horrifically he treated them. Even worse is his Heaven's Fall plan, which was so vile that Utopia Dopant [[EvenEvilHasStandards considered it a brutal act]]. Prospect would blast the area with an electric pulse and that would kill anyone that had not lived up to his standards for the project, referring to this as "cleaning out the test pool". When Daido foils his plan, it is revealed that was merciful compared to what happens if they try to escape him. The eyes he implanted on them to watch them are used to kill them when they leave his compound. Dr. Prospect then [[EvilLaugh laughs his head off]] at the fact he'd just slaughtered a village of innocent people while Katsumi is in shock over the massacre of the village he'd tried to save. His actions are so horrific that it [[DrivenToMadness drove]] [[spoiler:Katsumi]] insane.

''[[AC: Series/KamenRiderOOO]]'': While the show took a balanced look at {{greed}} and showed it did not need to be bad, these three demonstrate the worst elements of it:
* [[EvilGenius Kazari]], the [[CatsAreMean Feline Greeed]], is TheChessmaster responsible for many atrocities throughout the series. Of the [[BigBadEnsemble five original Greeed]], he has by far the most horrific way of making Yummy[[labelnote:MISC. INFO]] Yummy are MonstersOfTheWeek created by the Greeed from someones personal desires or greed[[/labelnote]] by implanting them within their host and controlling the host like a puppet, in some cases [[AndIMustScream while the host is conscious the entire time]]. After a while it consumes and traps them inside while they are fully aware of what is happening to them. Kazari's actions in the series proper are worse. He [[spoiler:used his own compatriots Mezool and Gamel as guinea pigs to see what would happen if a Greeed absorbed Core Medals that weren't their own, and was unfazed by there deaths, using this opportunity to absorb their Cores and become stronger. He later raised Lost Ankh as his own personal brainwashed warrior and helps Dr. Maki in trying to destroy the world]]. Sadistic and uncaring, even his own kind despise him for what he is.
* The aforementioned [[MadScientist Doctor Kiyoto Maki]], the DragonInChief to Kazari, is a prime example of what happens when [[TheSociopath antisocial behavior]] goes off the deep end. Before the day of his sister [[{{Jerkass}} Hitomi]]'s wedding, Maki burns his sister to death in her sleep just because she was going to abandon him. He then represses these memories and helps a MadBomber hosting Mezool's Yummy carry out attacks just to see the Yummy grow, not caring who dies in the process. When the swarm of Yummy hatches, he remorselessly locks his workers inside with them and watches the Yummy slaughter his colleagues. When he teams up with Kazari, his memories of Hitomi resurface, driving him to [[OmnicidalManiac destroy the world]]. True to his personal philosophy that "something's true value is only known when it ends", he absorbs five Purple Core Medals to begin transforming into a Greeed himself, the Dinosaur Greeed. Because the core medals make up the essence of a Greeed and give its user Greeed powers, Maki spawns Yummy that are omnicidal, with Maki finding their rampages to be merely "interesting". He also [[TheStarscream has no sense of loyalty to his allies]], as [[spoiler:Kazari learned the hard way when Maki impales him and rips all his cores out of him]]. Near the climax of the series, Maki gives two of his own Cores to Eiji (Kamen Rider OOO) solely to accelerate Eiji's greeedification and tosses the remaining Core Medals from the other Greeed into Uva to forcibly set his ultimate plan of destroying the world into motion.
* [[PredecessorVillain The original Kamen Rider OOO]] and the GreaterScopeVillain of the entire series was an ancient king of a lost civilization who wanted power over anything else. He had three alchemists and Gara create five sentient creatures, the aforementioned Greeed, for the sole purpose of killing them off to reach his goal of [[AGodAmI becoming an immortal god]]. After the alchemists and Gara succeeded, he [[YouHaveOutlivedYourUsefulness betrayed them and turned them into cell medals]], with [[AndIMustScream Gara still being conscious in this state]]. He then stole the core medals from the Greeed even though that would kill them over time. He used this power to take over a large portion of Europe and was well on the way to [[TakeOverTheWorld taking over the world]]. The prequel novel by Nobuhiro Mouri expands on his actions and shows that he cloned himself to attack neighboring countries; burned down villages that opposed him; invaded enemy camps using subterfuge; and used earthquakes and tsunamis to wipe out the Spanish Armada. After Ankh betrays the other Greeed by working with him, he [[ChronicBackstabbingDisorder double-crosses Ankh and stabs him in the back]] for his Core Medals and causes all the Greeed to be sealed away [[ItsAllAboutMe just so he could have the medals for himself]].

''[[AC: Series/KamenRiderFourze]]''
* [[TeensAreMonsters Tatsumori Yamada]]/[[MadArtist Aries Zodiarts]] was a transfer student who came to Amanogawa around the same time Ryusei came and became the undisputed king of Subaruboshi High. After getting the Aries switch he uses his new powers to control peoples' mental facilities that control sleep to put anyone he wants into a deep sleep. He forces the whole school into his little play-like world where everyone is graded on their performances. If they did bad jobs, then he would put them into a permanent sleep. He makes a DealWithTheDevil with Meteor, reviving Jiro if Meteor killed Fourze and he follows up on his deal despite the fact Aries could have revived Jiro without the need for the deal. He then decides to do a play called "School War", which has the Kamen Rider Club kill students before deciding to reverse the roles and have the Kamen Rider Club being tied up to poles and killed. Aries [[KnightOfCerebus stands out]] in this [[LighterAndSofter lighthearted]] series as a depraved villain who will go to any length to satisfy his own amusement.
* ''Movie War Megamax'' : [[BigBad Lem Kannagi]]/[[AGodAmI Super Galaxy King]] is a member of the insidious [[NebulousEvilOrganization Foundation X]] and wishes to use the power of the Astro Switches and the Core Medals from the future to become an all-powerful being. He will do absolutely anything to accomplish this, while taking a sick glee in rubbing his advantage in the faces of his enemies whenever he gets the chance. He essentially kills Gentaro's girlfriend, Nadeshiko for the SOLU she's composed of, and then rubs that fact in Gentaro's face. He also had no problem killing anyone that gets in his way without an ounce of remorse, or creating clones of all the Greeed and Sonozaki Dopants for his own evil purposes of ruling all of humanity.

''[[AC:Series/KamenRiderWizard]]'': Even in a series where the villains forcefully tried to turn humans into phantoms by making them give into despair, a select few stand out as much worse than the others:
* [[TheBrute Phoenix]] stands out even among [[AlwaysChaoticEvil the Phantoms]] as a [[AxCrazy complete psychopath]] who will go to horrific lengths in order to make Gates to create more phantoms. His methods involve beating a lady just so her child would give into despair; he later breaks into a hospital and randomly attacks innocent people, including patients who have no connection to the VictimOfTheWeek at all. Even his compatriot Medusa is frightened of his brutal tendencies since he has gone as far as to kill a Gate before the corresponding Phantom can manifest. His sadistic tendencies are so fierce that his boss Wiseman kept him to an observatory role at first rather than being allowed to directly intervene for fear of him going out of control.
* [[FromNobodyToNightmare Sora Takigawa]]/[[TheChessmaster Gremlin]] was once a SerialKiller who started to kill woman with white dresses and black hair after one dumped him, with this woman his first victim. He was later kidnapped to be made to give into despair and become a phantom. When a Human [[DespairEventHorizon gives into despair]] and becomes a [[OurDemonsAreDifferent Phantom]] they normally lose almost all aspects of their former personality, but Gremlin still retains Sora's desire to murder women and his [[PsychopathicManchild sadistic and childish personality]]. It originally seemed like he had noble intentions in protecting the Gate, but [[NotSoWellIntentionedExtremist this was revealed to be an act]]; he intended to indulge in his host's former taste and attempts to kill her for the sheer fun of it. He also makes no qualms about the fact that all the women he murdered were just for his own sick pleasure or DisproportionateRetribution.
* [[AxCrazy The Legion Phantom]] has the power to [[MindRape invade and destroy a personís Underworld]], which he abuses to satisfy his love of destruction. Seeking anyone altruistic enough for him to consider "Beautiful"--children included--Legion puts them in a catatonic state, a process shown to be extremely traumatic. With no loyalty to anything save his lust for destroying good people, Legion made an impression despite his limited screen time.

''[[AC: Series/KamenRiderGaim]]'': In a series that takes the franchise back to its DarkerAndEdgier roots, there are two heinous villains who cross the ultimate lines:
* [[MadScientist Professor Ryoma Sengoku]]/[[GreaterScopeVillain Kamen Rider Duke]], the creator of most Armored Rider gears, initially works as a researcher in the Yggdrasill Corporation's R&D division, and has [[LackOfEmpathy no concern]] about the lives of others except for himself, [[ForScience his research]], and those he deems an extension of himself. His goal is to grasp the Forbidden Fruit by any means necessarily in order to [[AGodAmI become a god]]. Being a backstabber, he cares not for his allies, simply [[ManipulativeBastard using them as a means to an end]] and disposing of them when they become unnecessary. His experiments on the Helheim Forest has caused damage, to the point where the world is on the brink of destruction. He also is a DirtyCoward who uses cheap tactics on his opponents, as is shown when he hacks his own Genesis Driver and then whenever he faces another Genesis Driver users, he uses a kill switch to disable his opponent's Genesis Drivers so they cannot fight back against him. Once the Overlords were dealt with, Ryoma has successfully manipulated Mitsuzane Kureshima into almost killing Kouta Kazuraba by providing him the life-threatening Yomotsuheguri Lockseed before he revealed to Mitsuzane that his promise to save Mai Takatsukasa's life was a lie, as he [[spoiler:cold-bloodedly murders her by dissecting the Forbidden Fruit, fused into her heart, from her]], just to obtain the Fruit for himself.
* [[DragonInChief Redyue]] is the only female member of the Overlord Inves. As a vile, selfish, and ManipulativeBitch, she corrupts Mitsuzane Kureshima into becoming her puppet and uses him to obtain human subjects for a machine that would revive the dead. She aggravates the humans into launching missiles, thereby forcing her superior Roshuo to redirect the missiles to America and to declare war against humanity. She is also not above MindRape, as seen when she tries to mentally break Kouta Kazuraba by portraying him in a hallucination as an Inves being attacked by his former mentor Yuya. Moreover, Redyue has a sickening obsession over backstabbing and killing those close to her, as seen when she ruthlessly kills [[spoiler:Roshuo]] after the latter defeats Kouta and Kaito Kumon. While the rest of her fellow Overlords, except for [[OnlySaneMan Roshuo]], were definitely evil themselves, Redyue stands out for her willingness to use any means necessary to play mind games with, and to commit genocide against, humanity, simply ForTheEvulz.

''[[AC: Series/KamenRiderDrive]]''
* [[MadScientist Professor Tenjuro Banno]]/[[BigBad Gold Drive]] is an [[ItsAllAboutMe egotistical]], sociopathic scientist with a god complex. After being refused funding by a potential investor, Banno has one of his Roidmude androids, Roidmude 002/Heart, assume the man's form and tortures it to take out his anger. Inserting negative emotions into the Roidmudes out of spite against his former partner, Banno's abuse leads to them becoming violently unstable, going on to rampage and kill countless people. Even after his death, Banno turns himself into a VirtualGhost, manipulating his own son into releasing his spirit before trying to kill him. Banno manipulates [[spoiler:Medic into being operated on, leaving her a puppet loyal to him and forces Heart to serve him, lying that he will restore Medic if he does so]]. Ultimately planning to digitize the entire world, Banno intends to only give robotic bodies to [[AGodAmI those who will bow to him]].

''[[AC:Series/KamenRiderAmazons]]'': In a series that runs on GreyAndGrayMorality scale, these two characters stand out as the most vile:
* [[GreaterScopeVillain Takaaki Tenjo]] is the [[CorruptCorporateExecutive Chairman]] of Nozama Pharmacy, helping develop the Amazonz, man-eating monsters that only have so long to live before becoming savage monsters. After their creation, Tenjo released the Amazonz from their lab [[TheSocialDarwinist to create an ecosystem where everyone will have to kill to survive]]. He and the other Nozama executives create the [[PrivateMilitaryContractors Nozama Protection Service]] (NPS) to deal with these beasts, but will gladly keep thousands alive in secret to ensure the Amazon Cells stay in their property, even creating Amazon Sigma from one of the dead members of the NPS to succeed the other Amazons. Tenjo is later disgusted with Sigma, not out of standards, but because he lacks the need to kill to survive. By the series's end, Nozama Pharmacy is out of business and countless Amazons are left roaming in the world to kill all around them, and when Tenjo is confronted by his co-workers for his deeds, he expresses nothing but utter delight. [[GreyAndGrayMorality In a series that shows a tragic side to both heroes and man-eating monsters alike without either side winning in the end]], Tenjo stood out as a being of unrepentant evil who, despite Nozama getting shut down, [[TheBadGuyWins ultimately ended up getting all that he wanted]].
* [[CardCarryingVillain Soji Shitashimo]], from season 1's "[[Recap/KamenRiderAmazonsEp7GameOfTheButchers GAME OF THE BUTCHERS]] and "[[Recap/KamenRiderAmazonsEp8HeroOrNot HERO OR NOT]]", proves that [[HumansAreTheRealMonsters humans can be just as monstrous as Amazonz]]. Initially appearing to be a fitness-obsessed jerk, Shitashimo is actually a SerialKiller of women who uses his junkyard as a dumping ground. Upon realizing that he is being suspected for murdering another woman, he tries to kill two agents sent to investigate him, Nozomi and Mamoru, by burning them alive, and when that fails, he decides to torture them instead, binding them with chains and forcing one to watch as he beats the other with a pipe, mocking Mamoru [[FantasticRacism for being an Amazon]] as he does so and telling him that he can only feel alive when beating something until it is "bloody broken and unable to move". Annoyed by Nozomi's attempts of ordering Mamoru to break the chains, he proceeds to savagely beat her in front of Mamoru with his own fists until her face is a bloodied mess, laughing at her suffering [[PsychopathicManchild like a child playing with a toy]]. His violent behavior serves to hide the fact that he is a DirtyCoward who begs to be spared when confronted in a proper fight. Unlike the Amazonz, Shitashimo is merely a vicious [[TheSociopath sociopath]] who enjoys killing innocent women simply because [[ForTheEvulz he can]].

* [[BigBad Masamune Dan]]/[[KillerGameMaster Kamen Rider Cronus]] is the first CEO of Genm Corp., a game company he uses to upload people into the digital world. First appearing as a victim of his son, Kuroto's, misdeeds, it is revealed that Masamune willingly allowed his child to infect and kill countless people for his own plans. After taking charge of the deadly video game, ''[[TheMostDangerousVideoGame Kamen Rider Chronicle]]'', Masamune tricks people into playing the game, collecting their data once they are in it to control their lives. Destroying any who oppose him, Masamune also uses his control of data to [[spoiler:delete a woman when her lover refuses to murder a heavily injured Taiga]] for Masamune. Reprogramming the FinalBoss of ''Chronicle'' so it will digitize the entire world, Masamune [[ControlFreak seeks to control everyone's life]]. When offered the chance for redemption, Masamune kills himself, making it impossible to revive those who died in his game, controlling and spiteful to the end.