Monster / Kamen Rider
"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, Kamen Rider Drive, "Why Are the Two Scientists in a Conflict?"

Kamen Rider has been 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 these very worst that have none.

  • The Great Leader of Shocker serves as the Overarching Villain 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 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 V3, where he would create the organization Destron and attempted to launch Operation: Japan Annihilation, which would release Deadly Gas 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 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 OOO, Den-O, All Riders: Let's Go Kamen Riders, 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 God Complex and desire to remake the world in his own image, he represents the very worst the franchise has to offer.

Kamen Rider
  • Former Nazi, Colonel Bakarashin Iinodevitch Zol, joined Shocker and quickly gets a reputation for brutality. Transferred to Japan to deal with Kamen Rider 2, Zol brainwashes children into become Shocker troops and gases an entire town. Apathetic to the fates of his own soldiers, Zol dismisses their deaths and even tests the powers of a resurrected mummy-like kaijin by letting him murder one of his mooks. Using another infectious kaijin, Zol has him kill a group of innocents, forcibly converting the survivor into a disease-carrier to spread more suffering. In the sequel series, Zol works with Doctor G to unleash toxic gas in Hokkaido and killing the innocent civilians.

Kamen Rider V3
  • 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 nerve gas, kidnapping children for slave labor, and 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 if they weren't so weak they wouldn't have died. When ordered by the Destron Leader to 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.

Kamen Rider Amazon
  • Ten-Faced Demon Gorgos is the leader of Geddon and a brutal sadist with a taste for human blood—which gives him power—and giving ironic deaths to his own men. A subordinate to Ruler, Gorgos is introduced pouring incendiary blood over the Amazon rainforest, burning a tribe alive and wounding 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 Eaten Alive by a giant snake. After kidnapping several students from an elementary school, Gorgos has them 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.

Shin Kamen Rider: Prologue: In one of the darkest entries in the franchise, these two are the most vile:
  • Iwao Himuro is the paranoid head of the ISS. An uncaring, heartless Bad Boss to his employees, Himuro considers those who refuse to cooperate with his projects as his own enemies, and has them either assassinated or imprisoned. Using his facility as a front for human experimentation, Himuro plans on obtaining financial gain through the mass production of super soldiers to be sold to the military industry. Forcing Shin's father to continue the research after having his former partner "resigned", Himuro denies his permission to not get his son involved, explaining that it was "too late for that". Armed with a submachine gun, Himuro guns down Ai, Shin's pregnant girlfriend, when she takes the bullet for him.
  • Giichi Onizuka/Onizuka Rider is one of Himuro's top scientists and secretly a misanthropic Serial Killer. Harboring an agenda of his own, Onizuka sabotages an experiment, altering both his and Shin's DNA, seeking to create an army of human-grasshopper hybrids to overthrow humanity, with him as their ruler. He wants Shin to be his first recruit, once trying to convince him into embracing his violent side. As a Cyborg Soldier Level 3, Onizuka regularly commits murders around the city For the Evulz, primarily targeting lone women. Introduced brutally killing a woman in the middle of the night, Onizuka proceeds to cut the throats of two undercover police officers investigating the slayings, and slaughters the cops who had arrived at the scene. When his secret lab is invaded by the CIA, Onizuka nearly kills the entire squadron, and tries to repeat this when he is indirectly released from containment by a group of agents.

Kamen Rider Kuuga: While the Gurongi Tribe is a race of Serial Killers, three of them stand out as among the worst of their kind:
  • The Gurongi lord, N-Daguva-Zeba, is a sadistic Blood Knight and Social Darwinist who cares nothing for the lives of humans or his own kind. Upon being reawakened, Daguva releases his 200 Gurongi, slaughtering the archaeologists who found them. Restarting a brutal game in which the Gurongi hunt humans, Daguva kills over one hundred of his own kind. When the titular Kamen Rider defeats one of his henchmen, Daguva ambushes him, mercilessly beating him and incinerating countless innocents before leaving. Continuing his systematic genocide, Daguva attempts to bring about "Ultimate Darkness", turning humans into twisted, vile creatures like himself and even after being fatally wounded by The Hero, dies laughing, hoping the latter will become as evil as himself.
  • Years after he blighted television screens in Japan, Go-Jaraji-Da (the Porcupine Gurongi) still stands as the standard to which other kaijin-of-the-week in Kamen Rider 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 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 Yusuke Godai snapped and killed Jaraji so savagely.
  • Go-Jaaza-Gi, the Shark Gurongi, is the only female member of the Gebageru subgroup and a Dirty Coward who stands in contrast to her battle-loving compatriots, choosing those who cannot fight back as her targets. Assuming the form of a well-dressed, glasses-wearing woman, Jaaza posts blogs on the internet to announce the massacres that she'll commit minutes prior to hunt for victims. To start her game, Jaaza infiltrated a plane and slaughtered the elderly passengers, forcing the pilot to send a distress call to the police before she killed him as well to make the plane crash; this incident alone had 244 causalities. After impaling Godai's shoulder with a harpoon, Jaaza planned on invading a cruise with 324 people on-board, most of which were children, intending on ending their lives simply because killing them would be "too easy".
  • In the manga by Toshiki Inoue et al., Akira Harada is the psychotic Serial Killer hunting down women in Tokyo at same time in which the aforementioned N-Daguva-Zeba was reawakened. A registered sex offender, Harada had tried killing himself for his goddess, and when he failed, Harada came up with the idea of "sharing his dream" with other people. Prior to having his identity revealed via DNA analysis, Harada had already murdered four women; by opening their chests, filling them with gunpowder, and burning them alive so they could become "human fireworks". When encountered by the detective investigating his murders, Kaoru Ichijo, Harada had killed another woman, and laughed at her death. Transported to an ambulance after attempting suicide, Harada slits the driver's throat and brags about being able to resume his serial killings. Harada is found by the Spider Gurongi on the parking lot, and when he sees the remains of the creature's victims, he feels joy, seeing this as his goddess's work. A childish maniac with an obsession for fireworks, Harada was proof that the Gurongi are not the only monsters roaming Tokyo.

Kamen Rider Ryuki: In this battle of where There Can Be Only One, these Riders stand out as particularly vile:
  • Takeshi Asakura/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 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 there can only be one. A vicious sadist, he's also responsible for the murder of an innocent woman, who turns out to be 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 his own estranged brother by feeding the latter to his Contract Monster, Venosnaker...after revealing that he was the one who set the fire which burned down their home, killed their parents, and separated them during their childhood in the first place. Asakura's evil is so great that it lives on in the franchise, with Asakura acting as a Fountain of Expies for numerous future villains.
  • Jun Shibaura/Kamen Rider Gai is a rich, Machiavellian college student and a Psychopathic Manchild who sees people's lives as tools to satisfy him. Recreating the Rider War in the form of a computer game that would send subliminal messages to players, Shibaura convinced his own colleagues to participate, always recording the loser getting brutally killed in the process. Putting himself in the position of ORE Journal chief editor, Shibaura planned on spreading city-wide violence by sending his program to their subscribers, and threatened to burn Shinji's Dragreder card if he tried to stop him, which would result in him being devoured by his Contract Monster. When Ren is unable to decide if he should kill him or not, Shibaura takes the opportunity to attack him, mocking Ren for not having the courage to kill him, stating that if a person is a Rider, then killing is a must. Meeting with Asakura, Shibaura gives him Zolda's true identity, despite the fact that he was the one who released him from jail, and gleefully watches Asakura holding a group of people hostage. In his last act of malice, Shibaura kidnapped Yui to reunite the Riders in order to make a "Rider Party" where he could see them fighting each other in his own definition of the ultimate game.
  • Masashi Sudoh/Kamen Rider Scissors is a 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.

Kamen Rider 555 (Faiz): In this Cyberpunk world that stands as one of the Darkest series in the franchise, these select two stand out:
  • Kitazaki/Dragon Orphnoch exemplified everything bad about Orphnochs. A young member of the Lucky Clover with the power to turn everything he touches into ash, Kitazaki, who lives solely for fighting and killing, sees the war between humans and Orphnochs as an opportunity to satisfy his boredom. Shortly before the events of the series, Kitazaki took part in a massacre that left several Ryusei students dead, breaking Mari's neck himself. When in the presence of other Orphnochs, Kitazaki uses his abilities to physically hurt them, such as pressing his fist against their cheeks. Even when not working for Smart Brain, Kitazaki enjoys murdering humans whenever he can, just for fun. After obtaining the Delta Gear, Kitazaki uses it to engage in brutal confrontations with other Riders, and tortures another Lucky Clover member when he tries to steal it from him. If the mission he is given is not fun enough, Kitazaki creates "games" to challenge the rest of the Lucky Clover, such as promising to slap other members in the arm if he kills their target first, knowing this would leave them without a limb. In one of his games, Kitazaki decides to kill their king, the Arch-Orphnoch, a being living inside the body of a little boy, just to prove his superiority, despite having the information that this would result in the extinction of his entire race.
  • Masahiko Minami is an amoral scientist who believes the Orphnochs deserve to be experimented on. Introduced stopping a police investigation, Minami recruits an innocent detective to spy on an Orphnoch, and orders his death when the man began sympathizing with Orphnochs. In his facility, Minami keeps an Orphnoch inside a glass box, calling him an "abomination". Minami believes that if humanity accepts the Orphnochs as equal beings, then humans will not be "pure" anymore, seeking to disable their shapeshifting abilities so they can die as monsters. Making a deal with Smart Brain to use Orphnochs as weapons, Minami captures Yuka and electrocutes her, ignoring complaints that the experiment could kill her, as he considers her a "worthless life". When she is saved by the Orphnoch he kept in a box, Minami sets up a squad of heavily armed officers to eliminate Yuka, Kiba and Takumi, indirectly causing her death. When his base is attacked by an enraged Kiba, Minami leaves his staff to die and escapes, but is later found and killed by him, spending his last moments laughing at his face and stating that the Orphnochs will never succeed. Despite his limited screentime, Minami proved himself to be far more malicious than many Orphnochs.
  • Seiden: Grotesque/Deformed Flowers: In this non-canon novel adaptation by Toshiki Inoue, Masato Kusaka/Kamen Rider Kaixa manages to be 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 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 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 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 so disgusted by this that he personally 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 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.

Kamen Rider Blade: 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:
  • Hiroshi Tennoji serves as the series' true Big Bad and absolutely reeks of 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: to create a new world order with himself as its ruler. Wishing to remake the world under him, his actions would produce countless tragedies throughout the series.
  • Isaka/Peacock Undead exemplifies how low 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 curbstomp him. Isaka tricks his defeated opponent to getting addicted to Schuld Ketsner seaweed, lying that the aggression-inducing plant would eliminate fear. When Tachibana's girlfriend Sayoko notices her lover's addiction, Isaka smugly kills her for attempting to clean up her lover.
  • Kamen Rider Chūshingura stageshow: Doctor Kira/Kamen Rider Killer is the egotistical B.O.A.R.D. researcher responsible for the dangerous Killer System. Believing that everyone else was jealous of his superior intelligence, Kira happily guns down a co-worker for having judged him, and enslaves three Orphnochs, using them as attack dogs to distract Kenzaki and Aikawa while he programs the Killer System. Having been betrayed by his assistant, Oishi, who steals the Faiz Driver from him, Kira sends the Orphnochs to kill her. After the Orphnochs are defeated, Kira ignores Oishi's attempts of convincing him to cancel the Killer System, and uses it to mutate himself into Rider form, easily overpowering the other Riders and trying to kill Oishi. When given a chance of redemption, Kira completely rejects it, considering the world "full of lies".

Kamen Rider Kiva: While the Fangire race are the major antagonists in the series, there are 3 specific members who crossed the ultimate lines:
  • The ruthless Bat Fangire/1986 King is the lord of all Fangires, using his position to annihilate the Merman and Franken races and persecute Jiro, the last of the Wolfen. Discovering his wife has fallen in love with Otoya Kurenai, the King tries to force her to kill Otoya, and when she refuses to do so, the King offers the surviving members of the races he meant to exterminate a chance to live if they kill Otoya for him. Transforming them all into conscious weapons for trying to escape from him, the King captures Otoya and torturously drains him of his life energy to feed his living castle. Threatening the life of his own infant son to prevent his wife from seeing Otoya again after he escapes, the King's actions disgust even his most loyal servant to the point that he aids Otoya, giving him the power to destroy the King.
  • Bishop, the Swallowtail Fangire, is King's calm, psychopathic right-hand man. A firm believer in the superiority of Fangires, Bishop informed the King of his wife's love for a human, resulting in Maya having her powers taken away from her. Trying to force Mio into embracing her fate as the new Queen, Bishop burns a Fangire in front of her when she refuses to kill him for having loved a human, later telling her that she must kill her Love Interest if she wants to be a true Queen. Under Taiga's orders, Bishop uses his powers to awaken Wataru's Fangire blood, almost making him murder his own friends. Seeing Mio as a failure, Bishop assassinates her and pins the blame on Wataru, fully intending on leaving him depressed. Proudly confessing his crimes to Taiga, Bishop is kicked out of the Checkmate Four and uses a magical crystal ball to drain the souls of multiple people. Planning on bringing the previous King back, Bishop revives the defeated Fangires and orders them to murder every human they come across, sacrificing his own soul to complete the ritual just so he could become one with the King and "destroy everything".
  • Rook, the Lion Fangire, is an excitement-seeking sociopath who murdered Yuri Aso's mother twenty years before the work takes place, leading to Yuri's hatred of Fangires. A genocidal maniac, Rook drove the Wolfen race to near-extinction, leaving Jiro as the sole survivor. To sate his boredom, Rook invents a game in which he must eat a selected group of people within a given amount of time, eating ice cream if he succeeds and punishing himself with electric shocks if he fails. Inventing a new game, Rook decides to do good deeds before getting himself killed, not out of a genuine interest in kindness but merely to keep himself entertained.
  • The Rhino Fangire 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 Wataru, who had generally tried to find the good in everyone, even Fangires, found his actions unforgivable.

Kamen Rider Decade
  • Otoya Kurenai/Kamen Rider Dark Kiva is King's substitute in the World of Negatives, possessing not only all of his Fantastic Racism, but also a charismatic personality to hide the fact that he is a cold-hearted, scheming dictator. Having created a law that qualifies humans as less than Riders, Otoya exterminated more than half of humanity in a genocide, and sends his minions to wipe out survivor camps. He also beats a Pseudo-Rider for defying him, commenting on how he must obey him for being a true Rider. Seeking to make Tsukasa his successor, Otoya tries to corrupt him into abandoning his journey and accepting the nature of his hateful world.

Kamen Rider Double
  • Shinkuro Isaka/Weather Dopant is a cold-hearted ally of The Museum obsessed with becoming the most powerful man alive. Originally a Straw Nihilist, Isaka found meaning in life upon witnessing the Terror Dopant attacking a group of people, feeling not fear, but joy by the act. Obtaining a Gaia Memory, Isaka committed a series of murders just to test his abilities; invading Terui's home, Isaka froze his family, despite his father begging him not to hurt his wife and daughter, not wasting any opportunity to remind Terui of the incident to mock him. Using his position as a physician to distribute Gaia Memories, Isaka modifies them to kill their users so he can steal their powers. Wanting the Terror Memory for himself, Isaka tries to coerce Saeko into killing her own father. A disturbingly realistic portrayal of a psychopath, Isaka's mind was unaffected by the repeated use of Gaia Memories, showing how he didn't need an excuse to become a monster.
  • W Returns: Eternal: Dr. Prospect/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 Psychic Powers. 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 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 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 drove Katsumi insane.

Kamen Rider OOO: 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:
  • Dr. Kiyoto Maki is an obsessive sociopath who, fearing his sister abandoning him for planning to marry, burns her to death the night before her wedding in her sleep. Helping a Monster of the Week fester for his experiments, when it hatches a swarm, Maki locks his own workers inside and watches the beasts slaughter them. When his memories of killing his sister resurface, Maki begins plotting to destroy the world, absorbing five Purple Core Medals to transform into the Dinosaur Greeed and gain the power for his nefarious scheme. Spawning destructive monstrosities, Maki observes their behavior as "interesting", killing Kazari to absorb his Cores and gain more power for himself. Giving two of his own Cores to Eiji Hino, Maki hopes to accelerate turning him into an unstable Greeed, giving his others to another Greeed in the hopes it will finish his plan to destroy Earth.
  • Kazari, the Feline Greeed, is one of the five original Greeed, making Monsters of the Week by taking over a person's physical body with an embodiment of their greed or desires, leaving them conscious but unable to control their actions. Kazari uses his companions, Mazool and Gamel, as guinea pigs to test what would happen if a Greeed absorbed Core Medals that were not their own, resulting in both of their deaths, to which Kazari callously devours both of their cores to strengthen himself. Brainwashing Lost Ankh into being his bodyguard, Kazari aids the aforementioned Dr. Maki in his plot to destroy the world.
  • The long deceased original Kamen Rider OOO was the greedy king of a long lost civilization. Desiring immortality, the king had his alchemists create the original Greeed, before betraying them and leaving them as conscious but immobile Cell Medals for millennia. Stealing the Core Medals from the Greeed even though this would kill them, the king used this power to try and Take Over the World, causing countless casualties in the name of his avarice, as revealed in the prequel novel by Nobuhiro Mouri. Double-crossing his own ally, the king seals all the Greeed away just to keep all their Medals for himself.

Kamen Rider Fourze
  • Tatsumori Yamada/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 Deal with the Devil 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 stands out in this lighthearted series as a depraved villain who will go to any length to satisfy his own amusement.
  • Movie War Megamax : Lem Kannagi/Super Galaxy King is a member of the insidious 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.

Kamen Rider Wizard: 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:
  • Phoenix stands out even among the Phantoms as a 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 Victim of the Week 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.
  • Sora Takigawa/Gremlin was once a Serial Killer 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 gives into despair and becomes a Phantom they normally lose almost all aspects of their former personality, but Gremlin still retains Sora's desire to murder women and his sadistic and childish personality. It originally seemed like he had noble intentions in protecting the Gate, but 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 Disproportionate Retribution.
  • The Legion Phantom has the power to 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.
  • Kamen Rider Wizard: The Promised Place: The Ogre Phantom is a power-hungry, cannibalistic Phantom who hunts and devours other Phantoms to gain their abilities. Unable to be contained by Wiseman, Ogre targeted WizarDragon to be his next victim, intending on devouring him to become the strongest Phantom in existence. Stealing the Hope Ring from Haruto, Ogre uses it to resurrect a despair-filled Koyomi, asking if he will get her killed again or leave her alive to wreak havoc. Invading Haruto's Underworld with Legion's powers, Ogre attempted to consume WizarDragon, incapable of realizing that it was now Haruto's symbol of determination.

Kamen Rider Gaim: In a series that takes the franchise back to its Darker and Edgier roots, there are two heinous villains who cross the ultimate lines:
  • Professor Ryoma Sengoku/Kamen Rider Duke is a researcher who created most of the Armored Rider gears. Intending to become a god with the Forbidden Fruit, Ryoma will exploit and backstab anyone to get what he desires and is a Dirty Coward who will use any cheap tactic to win. Damaging Helheim Forest with his experiments, threatening to destroy the world, Ryoma reacts with apathy. Manipulating Mitsuzane Kureshima into almost killing Kouta Kazuraba by promising to save another's life, Ryoma reveals his promise to be a lie before murdering Mitsuzane's Love Interest in cold blood, taking the Forbidden Fruit which was fused with her heart to obtain its power for himself.
  • Redyue is the only female member of the Overlord Inves. As a vile, selfish, and Manipulative Bitch, 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 Mind Rape, 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 Roshuo after the latter defeats Kouta and Kaito Kumon. While the rest of her fellow Overlords, except for 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 For the Evulz.

Kamen Rider Drive
  • Professor Tenjuro Banno/Kamen Rider Gold Drive is an 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 Virtual Ghost, manipulating his own son into releasing his spirit before trying to kill him. Banno manipulates 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 those who will bow to him.
  • 010 Paint Roidmude is a Mad Artist whose sadism disturbs even other Roidmudes. During the Global Freeze, Paint personally attacked Kiriko, turning her arm into data until she was saved by Proto-Drive, an event which traumatized her. Six months later, Paint assumed the identity of a gallery owner who he had placed in a painting, and with the assistance of his apprentice, did the same thing to several women who wandered near the gallery, all while they were aware of their situation but unable to escape. Realizing that Kiriko is investigating the serial kidnappings, Paint triggered her post-traumatic stress by attacking her once again. Using Mashin Chaser as a distraction, Paint planned on fleeing to another area so he could find a new hunting ground, but not before he tried to trap Kiriko in a painting, seeking to immortalize her expression of pure and sheer terror.

Kamen Rider Amazons: In a series that runs on Grey and Gray Morality scale, these three characters stand out as the most vile:
  • Takaaki Tenjo is the 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 to create an ecosystem where everyone will have to kill to survive. He and the other Nozama executives create the 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. 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, ultimately ended up getting all that he wanted.
  • Soji Shitashimo, from season 1's "GAME OF THE BUTCHERS and "HERO OR NOT", proves that humans can be just as monstrous as Amazonz. Initially appearing to be a fitness-obsessed jerk, Shitashimo is actually a Serial Killer 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 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 like a child playing with a toy. His violent behavior serves to hide the fact that he is a Dirty Coward who begs to be spared when confronted in a proper fight. Unlike the Amazonz, Shitashimo is merely a vicious sociopath who enjoys killing innocent women simply because he can.
  • The Elephant Amazon, from season 2's "PERSONA NON GRATA" and "QUO VADIS?", is the most repulsive New-Type to be investigated by the 4C. Using his clinic as a front to find unsuspecting victims, Elephant's method of killing his prey consists of inserting a long proboscis into the victim's ear and dissolve the brain while they are still conscious, having done this to four people in just one week. After drinking the brain of a woman and leaving her to convulse, Elephant killed a random man, before trying to do the same to a woman who found the body, excitingly calling her his next patient. A callous sadist who gladly accepted his nature, Elephant was a reminder that not every Amazon tried to contain the craving for human flesh.

Kamen Rider Ex-Aid
  • Masamune Dan/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, 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 delete a woman when her lover refuses to murder a heavily injured Taiga for Masamune. Reprogramming the Final Boss of Chronicle so it will digitize the entire world, Masamune 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.

Kamen Rider Dragon Knight
  • General Xaviax/Kamen Rider Wrath is a narcissistic alien warlord and the one behind all the tragedies throughout the series. Originating from the planet of Karsh, Xaviax devastated his own planet with a long-lasting civil war and proceeded to enslave civilizations from other planets, starting with Ventara. Having badly injured his former ally Eubulon and vented nine of the original Ventaran riders, Xaviax saw Earth as his next target. Kidnapping humans and leaving them in coma, Xaviax manipulated a group of people into becoming riders, taking advantage of Kit's love for his father, one of his victims. Xaviax's ultimate goal was to not only make humanity his next victim, but to hunt for the Ventaran riders who had escaped from him, especially Len. Succeeding in bringing riders to his side, Xaviax orders his right-hand man to vent the agents who he considers to be a loose canon, and was indifferent to his venting at the hands of a furious Len, possessing the body of a comatose patient to use him as his new puppet. Failing to achieve his goals, Xaviax made a final attempt to manipulate the riders before his death. While seemingly caring for his planet, his superficial charm, extreme methods and proud towards his own cruelty reveal his noble intentions as the empty excuses of an unfeeling tyrant with a superiority complex and a self-proclaimed evildoer.