Evil Imagin
Imagin are the creatures that arrive from the future to conquer the past for Kai. Some are evil and assist Kai in changing time, while few have justice within them and refuse to aid Kai, lending their power to the Kamen Riders in order to fight. Imagin listed here are ones that serve major purposes in the story, being more than a monster of the week.
Bat Imagin
The Bat Imagin has the ability to create wings to fly with and attacks using sonics. After attaching himself to Tetsuo, Tetsuo wishes for the return of the jinglebell keyholder that he lost. The Bat Imagin attempts to fulfill this wish by attacking anyone with a keyholder that jingled. He somehow survives being hit by Sword Forms's Extreme Slash in their first encounter and continues this until fulfilling the contract. When he travels to the past, the Bat Imagin takes over Tetsuo's body and begins causing havoc until Den-O appears and forces him to abandon Tetsuo. When destroyed by Den-O, the Bat Imagin becomes Gigandeath Heaven and is ultimately defeated by DenLiner Gouka. He is based on The Bat, the Birds, and the Beasts.
Episodes 1-2
Chameleon Imagin
The Chameleon Imagin wields a whip and can breathe fire. When Yu Yamagoshi wishes for "a hell of a lot of money," the Chameleon fulfills this wish by attacking banks and stealing money. When he travels to the past, the Chameleon Imagin begins to destroy various cars while in control of Yamagoshi. The Chameleon Imagin overpowers Den-O Plat Form until Momotaros apologizes for his earlier squabble with Ryotaro and takes over as Den-O Sword Form, slicing the Imagin in half at the waist with his Extreme Slash and destroying him. He is vaguely based on the Frog Prince.
Episodes 3-4
Crust Imagin
The Crust Imagin wields a boomerang-like weapon and uses seaweed-like tendrils to attack. When Daiki Saito wishes to be back on his soccer team, the Crust fulfills this wish by hospitalizing the other members. He then travels to the past and begins attacking the soccer stadium. When destroyed by Den-O Rod Form, the Crust Imagin becomes Gigandeath Hades and is then destroyed by DenLiner Isurugi. He is based on The Crab and the Monkey.
Episodes 5-6
Crow Imagin
The Crow Imagin wields a cane and uses his feathers as explosive shurikens. When Yumi Saito wishes to forget about her ex-boyfriend, the Crow Imagin fulfills this wish by destroying anything playing Four Seasons Concerto No. 1: Spring. Once in the past, he "erases" all of the members of Yumi and Toyama's wedding party. The Crow Imagin is defeated by Den-O Sword Form after Rod Form manages to counter his flight ability. He is based on The Crow and Other Birds.
Episodes 7-8
Rhino Imagin
The Rhino Imagin wields a mace and possesses brute strength. When Shinji Kikuchi wishes to be the best karate master in Tokyo, the Rhino fulfills this wish by attacking all of his former competitors. When he travels to the past, the Rhino Imagin destroys the karate arena, and is confronted by Den-O's Sword Form and manages to have the upperhand until Kintaros forms a contract with Ryotaro, turning Den-O to Ax Form. Despite his best attempts, the Rhino's mace is shattered by Den-O's brute strength, allowing him to be struck down by the Dynamic Chop. He then reforms into Gigandeath Hell and is destroyed by DenLiner Rekkou. He is The Naked Rhinoceros.
Episodes 9-10
Ivy Imagin
The Ivy Imagin wields a double-bladed sword and uses his vines as weapons. After sensing Kensaku Kobayashi's subconscious desire to be with his daughter Kasumi, the Ivy Imagin fulfills this wish by preventing her career from advancing. When he travels to the past, the Ivy Imagin destroys the Kobayashi's hometown, and is eventually defeated by Den-O Ax Form. Due to Kintaros' interference in the past, the Ivy Imagin is prevented from ever making the contract at all, negating his damage. Based on Jack and the Beanstalk.
Episodes 11-12, 49 and Saraba Kamen Rider Den-O The Movie: Final Countdown
Owl Imagin
The Owl Imagin wields a sword and uses his feathers as bombs, just like the Crow Imagin. When Shuji Toyama wishes for the park he works at to become a better place for the stray animals that live in it, the Owl fulfills this wish by first attacking any human who tries to enter the park, then, eventually barricading the entrance to the park with cars, and debris. When he travels to the past, havoc ensues before the Owl Imagin is defeated by Den-O Gun Form, and then destroyed by DenLiner Ikazuchi when the Imagin's essence splits and forms into two Gigandeaths. Based on The Owl and the Birds.
Episodes 13-14
Whale Imagination
The slow and less-intelligent Whale Imagin wields a staff with a fluke at one end and has the ability to blast water from its mouth. When Kosaku Higuchi wishes to get rid of his drinking problem, the Whale Imagin fulfills this wish by attacking anyone who knew of his drinking problem: former employees and a sake vendor. Once in the past, he attacks people who were having a hanami party under a starlit night sky. The Whale Imagin is fought and defeated by Den-O Sword Form, being destroyed by the Extreme Slash. Another Whale Imagin was amongst the massive army of Imagin that invaded both the past and the present as part of Kai's plan to ensure the Imagins' future, this armed with a sword rather than a staff. Based on the Whale from Pinocchio.
Episodes 15-16, 47, & Saraba Kamen Rider Den-O The Movie: Final Countdown
Wolf Imagin
The Wolf Imagin is a hot-tempered Imagin that wields a sword able to launch crescent energy beams. When Yuka Sawada wishes to relive her high school days, the Wolf fulfills this wish by vaporizing high school girls and giving their possessions to Yuka. When the Wolf Imagin travels to the past, Gun Form is the first to confront him, stopping the Wolf Imagin from completing its mission. After being stuck for a day in the past with no new information from Kai of Sakurai's location, the Wolf Imagin goes insane with bored rage and decides to destroy anything in his path to complete the mission. Although both Rod and Ax Form fought the Wolf Imagin, Sword Form is the one that finally destroys him. The Wolf Imagin later returns in the Kamen Rider Den-O Hyper Battle Video, seen amongst the other Imagin aboard the DenLiner exercising along with them before making his move around Ryutaros' turn. After mocking Ryotaro, he is destroyed by Den-O Liner Form. The Wolf Imagin is also one of the two antagonistic Imagin featured in the Imagin Anime 2 shorts, making two appearances. Based on the wolf from the Little Red Riding Hood
Episodes 17-18, and Hyper Battle Video
Jelly Imagination
Based on the Jellyfish's Errand, the Jelly Imagin possesses electrical tentacles and the ability to liquefy his body. When Kohei Amano wishes to unearth the time capsule that had been left behind by his girlfriend, the Jelly Imagin fulfills its contract by forcing Amano to unearth any time capsule that he sees being buried. Once in the past, the Jelly Imagin attacks a bunch of picnickers that are near the original time capsule's burial site. Though Den-O Sword Form is unable to defeat him, the Jelly Imagin is destroyed by Zeronos Vega Form.
Episodes 19-20
Tortoice Imagin
The Tortoice Imagin is actually two Imagin: a dominant and slow tortoise-half with an energetic hare-half generally dormant inside the Imagin's body unless needed. The Tortoice Imagin can fire large pellets out of his mouth and has a serious personality while his hare-half has a playful, childish personality. The wish of the Imagin's contractor, Tanaka, is unclear due to the fact that the wish is made at the time he is half-awake. However, the Tortoice Imagin is not able to travel back in time because Tanaka cannot remember making a contract. Once Tanaka is able to remember, the Tortoice Imagin travels back in time only to be defeated by Zeronos and Den-O taking on the Imagin and his hare half. However, the two halves reform into Gigandeaths, with Hell attempting to escape until the ZeroLiner corners it. The Heaven is destroyed by DenLiner Isurugi's beams and the Hell Gigandeath is chopped to pieces by Zeroliner Niginata's blades and explodes. Based on the Tortoise and the Hare.
Episodes 21-22
Scorpion Imagin
The Scorpion Imagin, armed with a saber, made a contract to abduct Shiori for Akio Masuda, preferring to grant an "easy" wish with no tolerance for those who attempt to meddle in his affairs. Though halted by Den-O twice, the Scorpion managed to go back to time. The Scorpion Imagin was fought by Den-O's Rod Form before Ax Form finishes him off. Based on the Boy Hunting Locusts.
Episodes 23-24 & 49
Spider Imagin
The red-eyed Spider Imagin, able to fire energy webs from his arms, was bent on granting Masashi Aoki's wish for his sister Mayu to see a starry sky, intent on tying her to a radio tower to fulfill it. Though initially defeated by Zeronos, it turned out that the Spider Imagin split itself in two prior to the fight with a more serious version outliving his crazed "brother." The second green-eyed Spider Imagin caused a massive blackout to fulfill the wish without trouble. Once in time, the Spider battled Den-O Gun-Form to avenge his "brother" until future Zeronos interfered and Sword-Form finished the fight. The red-eyed Spider Imagin later returns in the Kamen Rider Den-O Hyper Battle Video, amongst the other Imagin aboard the DenLiner exercising before making his move around Ryutaros' turn. After mocking Ryotaro, he is destroyed by Den-O Liner Form. Based on the Tsuchigumo Story.
Episodes 25-36 & Hyper Battle Video
Imagin Episodes 1-25 | 26-38 | 39-49
Series:  Kamen Rider Den-O