Cross of Fire

The Cross of Fire (クロスオブファイヤー) is, according to Amadum, the embodiment of the power of the Kamen Riders symbolised by a burning crucifix representing the sign of their sin, in being creations of evil. But during the final battle Amadum was wrong as the Riders used their powers to overcome Amadum, leaving him shocked that the riders were not creations of evil as he thought.

Showa

 * Kamen Rider: The Double Riders were two men who were kidnapped by Shocker and modified to become their ultimate cyborgs. The first Kamen Rider was Takeshi Hongo, later known as Kamen Rider #1, who was freed by Professor Midorikawa before he could be brainwashed. The second was Hayato Ichimonji, later known as Kamen Rider #2, who was rescued by Hongo.
 * Kamen Rider V3: Though Shiro Kazami was rebuilt into V3 by the Double Riders for benevolent purposes, he was built with their power and remodeled just as they were by Shocker. Joji Yuki was a Destron scientist that became the cyborg Riderman that was intended to defeat V3. However, Riderman (gradually) joined V3's side when he realised the evil of Destron.
 * Kamen Rider X: X-Rider is an anomaly; while indeed reminiscent of the previous Riders, the Kaizorg was an invention intended for marine exploration before Keisuke Jin was modified by his father to fight G.O.D..
 * Kamen Rider Amazon: Daisuke Yamamoto was given the Incan GiGi Armlet which he used to become Amazon to fight Geddon and then the Garanda Empire, who possessed the GaGa Armlet and wished to gain the GiGi Armlet as well to conquer the world. This is somewhat questionable though, as the Incan`s didn`t seem to create the Armlets out of malicious intentions. It should also be noted that Elder Bago equipped the GiGi Armlet onto Daisuke to fight Geddon as well as to save him from dying.
 * Kamen Rider Stronger: Shigeru Jo joined Black Satan after the death of a close friend, one whom he considered his mentor. Promised power, and fueled by a desire for revenge, he undergone surgery to become one of Black Satan's super warriors. However, Shigeru knew that Black Satan were in fact the murderers of his friend; he was using Black Satan in order to gain new powers. The newly powered up Shigeru (Kamen Rider Stronger) escaped from the Black Satan headquarters before they could brainwash him into following their campaign of evil.
 * Kamen Rider (Skyrider): Neo-Shocker intended for Hiroshi Tsukuba to serve them when he was modified into a cyborg. However, Hiroshi escaped their complex and fought them as Skyrider.
 * Kamen Rider Super-1: Super-1 is yet another anomaly, as he was created by the International Space Development Program for space exploration before fighting the Dogma Kingdom.
 * Kamen Rider ZX: Ryo Murasame was captured by the Badan Empire and turned into the cyborg warrior ZX; he only snapped back to good after an on-field accident.
 * Kamen Rider Black: The King Stones were created for the Gorgom Century Kings, with Kotaro Minami (Kamen Rider Black) and Nobuhiko Akizuki (Shadow Moon) turned into cyborg Century Kings, and the sole victor would become the Creation King by having both stones of the Sun and the Moon.
 * Kamen Rider Black RX: Black RX is an evolution of Black.
 * Kamen Rider Shin: Though Shin was modified by doctors at the Institute of Super Science as part of a project to strengthen the human body from disease, they were funded by a syndicate group who planned to use the research to create super-soldiers. As well as that, ISS geneticist Giichi Onizuka, who had himself modified, wanted to create a new species, by fusing a grasshopper's DNA with the test subject's, in order to start a new civilization and be their god.
 * Kamen Rider ZO: Both ZO and the Neo Organism he fought against were created by the mad scientist Doctor Mochizuki, who dreamed of creating the "perfect lifeform".
 * Kamen Rider J: J is an anomaly, as he was created by the benevolent Earth Spirits. But from SIC Hero Saga, the prototype of J is ZO.

Heisei

 * Kamen Rider Kuuga: While Kuuga was created to protect the Linto Tribe, the "Kuuga" character was not invented by the Linto but is actually borrowed from an incomplete Gurongi, tied to N-Daguva-Zeba who like Kuuga possesses an Amadam.
 * Kamen Rider Agito: The powers of Agito (as well as Gills and Another Agito) and the Lords he fought against originated from rival god-like brothers known as the Overlords, with the Overlord of Light bestowed the Seeds of Agito to humanity on his deathbed so they could evolve beyond the control of Overlord of Darkness, who in return, created the Lords to hunt down and wipe out the Agitos. It should be repeated that the Overlord of Light bestowed the Seeds of Agito to stop his brother, making Agito somewhat an anomaly.
 * Kamen Rider Ryuki: Ryuki and his contemporaries, whose nature varied between good and evil, fought by making contracts with certain Mirror Monsters. Though the Mirror Monsters were not created for evil purposes, they did result in the deaths of innocent humans. This is however not out of malice, but simply because they were considered food by the Mirror Monsters.
 * Kamen Rider 555: The Rider Gears of Kamen Rider Faiz and his contemporaries were created by Smart Brain to protect the Orphnoch King when he awakes, with the Faiz and Kaixa Gears being made for only Orphnochs to wear, with Delta still being in the prototype stages (thus allowing normal humans to use the Delta Gear). Takumi Inui, the main user of the Faiz Gear, is an Orphnoch himself, the Wolf Orphnoch. This however, is slightly questionable as some Orphnochs only tried to protect the Orphnoch King for their own survival, due to Smart Brain's many connections.
 * Kamen Rider Blade: Blade and his contemporaries fought using the power of the Undead they fought against via the Rouze Cards, which are sealed forms of the Undead. Also, the users of the Rider Buckles must meet a level of synchronization with Undead DNA to use them, with Blade's synchronization being so high, it made the King Form combine all of the sealed Suit of Spade Undead and put him at risk of becoming a Joker-classed Undead, which he eventually becomes to stop the Battle Royale.
 * Kamen Rider Hibiki: The Oni Rider contemporaries of Hibiki and himself, while trained to fight the monstrous Makamou, are demons that have the potential to become evil and, in the case of the A.R. Hibiki, part-Makamou themselves.
 * Kamen Rider Kabuto: The Masked Rider System that Kabuto and his contemporaries herald from was developed by the Native Worms to give to the humans that would form ZECT, to fight against the more malevolent Worms that would arrive later, though some of the Native Worms were not exactly saints, including the inventors of the Masked Rider System, who installed a "Red Boots" program into a few of the suits.
 * Kamen Rider Den-O: Den-O, as well as Zeronos and New Den-O, fought against evil Imagin by bonding with benevolent Imagin partners. Not all the Imagin`s seemed evil however, as they mostly seemingly tried to change the timeline to insure their own survival rather than to kill humans for the sake of killing humans.
 * Kamen Rider Kiva: This is an anomaly as the Kivats can freely bestow upon their powers to any creature they choose with most of the hosts being good from the start, though the energy they emit through their fangs to allow the individual to transform into a Kiva must have Fangire blood or DNA within them, otherwise the energy will kill them, such as was the fate of the second Dark Kiva. Since Kivat-bat the 3rd chose to help humanity with Wataru from the start, this wouldn`t make Kiva's source of power evil. It should also be noted that the Fangires attacked the humans to drain their life energy due to it being necessary for their survival; however, some Fangires become addicted and succumb to their gluttony.
 * Kamen Rider Decade: The Decadriver was created for Tsukasa Kadoya to become Decade and lead Dai-Shocker as its Great Leader, only for Tsukasa to fight monsters and eventually Dai-Shocker itself after losing his memory. The Diendriver was created as a back-up, but it was stolen by Daiki Kaito. By extension, since they use the powers of previous Kamen Riders, they're connected to their evils as well.
 * Kamen Rider W: Both the Futo Kamen Riders and the Dopants they fought against transformed by using Gaia Memories.
 * Kamen Rider OOO: The OOO Driver and Core Medals were created so the First Kamen Rider OOO could rule the world. The creation of the Core Medals resulted in the Greeed, and by extension the Yummies, that would be fought by the modern OOO, Eiji Hino, who was aided by the rogue Greeed, Ankh, who had helped the first OOO until he was betrayed. Eiji was also mutated into a Greeed for the Purple Medals for a time until the ones in his body were destroyed when they got sucked into the black hole caused by the Kyoryu Greeed's death, reverting him back to a normal human.
 * Kamen Rider Fourze: Both the Kamen Riders (Fourze and Meteor) and the Zodiarts transform using Switches reverse-engineered from the Core Switch.
 * Kamen Rider Wizard: Wizard and his contemporaries could use magic and transform thanks to the usually malovelent Phantoms, by holding an immature Phantom (which are then known as an Enslaved Phantom) within their bodies. As noted by Amadum, Wizard was born from the Sabbath which created the Phantoms, and Beast had Chimera inside in his body after donning the Beast Driver.
 * Kamen Rider Gaim: The Sengoku Drivers used by Gaim and his contemporaries were produced by the Yggdrasill Corporation; while not known to have truly malevolent ambitions, the higher-ups (who later use Genesis Drivers) have been shown to commit malicious acts. The Lockseeds that they use to transform also empower the Inves that they fight against, and can even turn people into monsters by consuming the raw state of the Lockseeds. Kouta and Kaito also became Over Lord Inves through respectively exposure to the Forbidden Fruit via the Kiwami Lockseed and eating one of Helheim's Fruit with sheer force of will.
 * Kamen Rider Drive: Krim Steinbelt, inventor of the Shift Cars, Tridoron, and the Drive Driver, gave his collegue, Dr. Banno, the "heart" of his inventions, Core Driviars, out of a wish by Banno, when research of his inventions, the Roidmudes, had hit a dead end, only for them to go rouge and kill Banno and Krim, but not before Krim could upload his conscience into the Drive Driver. Eventually, the Roidmudes invented Viral Cores, dark knockoffs of the Shift Cars that would serve the purpose of helping Low-Class Roidmudes evolve much faster into more powerful forms. Go Shijima outright stated that since his and Shinnosuke's powers come from the same source of the Roidmudes, that makes the Kamen Riders monsters as well. However, in a technical sense, the Roidmudes are an inversion of the Cross of Fire inversion, as the Core Driviars are the reason they are even able to move.
 * Kamen Rider Ghost: TBA