The Worlds Kaijin serve as the fictional monsters of Kamen Rider Decade.
List of Worlds Kaijin[]
N-Gamio-Zeda[]
- World: Kuuga's World
N-Gamio-Zeda-(3) The wolf-like king of the Gurongi. Destroyed by Kamen Rider Decade and Kamen Rider Kuuga.
Beetle Fangire[]
- World: Kiva's World
Beetle Fangire-(4-5, 31) A beetle minster. Defeated by Kamen Rider Decade and Kamen Rider Kiva. He shatters after Tsukasa plays a sad violin song. Resurrected by Super Apollo Geist, he is destroyed by Kamen Rider Kuuga.
Paradoxa Undead[]
- World(s): Ryuki's World and Blade's World
Paradoxa Undead-(6-9, 31) A phyllocrania monster who assumes the guise of Kamen Rider Abyss-(6-7) before being defeated by Kamen Rider Decade and Kamen Rider Ryuki. He is destroyed again along with the Joker by Kamen Rider Decade and Kamen Rider Blade. Ressurected by Super Apollo Geist, he is destroyed by Kamen Rider Kiva.
Abyssodon[]
- World: Ryuki's World
Abyssodon-(7) A shark Contract Monster of Kamen Rider Abyss and the combined form of Abysshammer and Abysslasher. Destroyed by Ryuki Dragredder.
- Abysshammer-(6-7) A hammerhead shark monster.
- Abysslasher-(6-7) A shark monster.
Tiger Orphnoch[]
- World: Faiz's World
Tiger Orphnoch-(10-11, 31) A tiger monster who has the ability to ressurect other Orphnochs. Destroyed by Kamen Rider Decade. Ressurected by Super Apollo Geist, he is destroyed along with the Alligator Imagin by Kamen Rider Decade Complete Form.
Taurus Ballista[]
- World: Agito's World
Taurus Ballista-(12-13, 31) A taurus monster who is a Buffalo Lord. Destroyed by Kamen Rider Decade and Kamen Rider G3(Yuusuke). Ressurected by Super Apollo Geist, he is destroyed by Kamen Rider Hibiki.
Alligator Imagin[]
- World: Den-O's World
Alligator Imagin-(14-15, 31) An alligator monster. Destroyed by Momotaros. Ressurected by Super Apollo Geist, he is destroyed along with the Tiger Orphnoch by Kamen Rider Decade.
Goludora[]
- World: Den-O's World
Goludora-(Den-O & Decade) A grasshopper monster. Destroyed by Kamen Rider Den-O.
Shilubara[]
- World: Den-O's World
Shilubara-(15, Den-O & Deacde) A dragonfly monster. Destroyed by Kamen Rider Den-O Super Climax Form.
Phylloxera Worm[]
- World: Kabuto's World
Phylloxera Worm-(16-17, 31) A phylloxera monster who can transform into Kamen Rider TheBee. Destroyed by Kamen Rider Decade and Kamen Rider Kabuto. Resurrected by Super Apollo Geist, he is destroyed by Kamen Rider Diend.
Gyuki[]
- World: Hibiki's World
Gyuki-(18-19) An ox monster who is Hibiki, the original Kamen Rider Hibiki. Destroyed by Kamen Rider Hibiki(Asumu).
Bossroach[]
- World: Diend's World
Bossroach-(22) A cockroach monster that resembles the Caucasus Undead. Destroyed by Kamen Rider Decade Complete Form and Kamen Rider Kiva Emperor Form.
Chinomanako[]
- World: Shinkenger's World
Chinomanako-(24-25) A sea cucumber monster that is a Gedoushu and can use the Diendriver to become Chinomanako Diend Form-(24-25). Destroyed by Shinken Red and Kamen Rider Decade Complete Form.
Schwarian[]
- World(s): Black RX's World and Black's World
Schwarian-(26-27) A walrus robot that is a Strange Demon Monster of the Crisis Empire. Destroyed by Kamen Rider Decade Comlete Form and Kamen Rider Agito Shining Form.
Llumu Qhimil[]
- World: Amazon's World
Ten-Faced Demon Llumu Qhimil-(28-29, OOO, Den-O, All Riders) A kite monster. Destroyed by Kamen Rider Amazon. He is destroyed again by the Great Leader.
Thorn Fangire[]
- World: Rider War World
Thorn Fangire-(30) A sea cucumber monster. Destroyed by Kamen Rider Decade Complete Form and Kamen Rider Ryuki Survive Mode.
Previous Enemies[]
In Kamen Rider Decade, various enemies from previous Kamen Rider Series appears.
- Various Fangires-(1) They include the Rat, Mantis, and Seamoon Fangires.
- Various Undead-(1) They include the Pecker, Squid, and Caucasus Undead.
- Various Orphnoch-(1) They include the Octopus, Okra, Pigeon, Dolphin, and Rhinoceros Beetle Orphnoch.
- Various Imagin-(1) They include the Spider, Bat, Molech, Bloodsucker, and Whale Imagin.
- Various Worms-(1) They include the Culex, Sectio, and Sepultura Worms.
- Me-Gyarido-Gi-(1-2) A hermit crab monster. Destroyed by Kamen Rider Kuuga Dragon Form.
- Ra-Dorudo-Gu-(1-2) A condor monster. Destroyed by Kamen Rider Kuuga Pegasus Form.
- Go-Baberu-Da-(2) A bison monster. Destroyed by Kamen Rider Decade.
- Go-Bemiu-Gi-(2) A sea snake monster. Destroyed by Kamen Rider Decade.
- Me-Biran-Gi-(2) A piranha monster. Destroyed by Kamen Rider Kuuga.
- Various Gurongi-(3) N-Gamio-Zeda created them from various humans. Absorbed by N-Gamio-Zeda.
- Spider Fangire-(4) A spider monster.
- Lion Fangire-(4) A lion monster. Destroyed by Kamen Rider Decade.
- Swallowtail Fangire-(4-5) A swallowtail monster. Destroyed by Kamen Rider Decade.
- GuldThunder-(6) A red fenghuang monster.
- Zebraskull Bronze-(6) A zebra Monster.
- Buffalo Undead-(8) A buffalo monster. Sealed by Kamen Rider Blade.
- Elephant Undead-(8) An elephant monster. Destroyed by Kamen Rider Decade(as Kamen Rider Ryuki).
- Capricorn Undead-(8) A goat monster. Destroyed by Kamen Rider Decade.
- Joker-(8-9) Hajime Shijo/Kamen Rider Chalice's true longhorn beetle form. Destroyed along with the aradoxa Undead by Kamen Rider Decade and Kamen Rider Blade.
- Butterfly Orphnoch-(10) A butterfly monster. Destroyed by Kamen Rider Faiz.
- Lobster Orphnoch-(10-11) A lobster monster and the sole female member of Lucky Clover. Destroyed by Kamen Rider Faiz. Quickly ressurected by Momose, she is destroyed by Kamen Rider Decade.
- Dragon Orphnoch-(10-11) A dragon monster and a jock member of Lucky Clover. Destroyed thrice by Kamen Rider Decade.
- Centipede Orphnoch-(10) A centipede monster and a booksmart member of Lucky Clover. Destroyed by Kamen Rider Decade(as Kamen Rider Blade). Resurrected by Momose, he is destroyed again by Kamen Rider Diend.
- Me-Badjisu-Ba-(12) A bee monster. Destroyed by Kamen Rider G3(Yuusuke).
- Me-Ginoga-De-(12) A mushroom monster. Destroyed by Kamen Rider Diend.
- Zu-Mebio-Da-(12) A leopard monster. Murdered by two Ant Lords as she atttempted to escape from Diend.
- Formica Pedes-(12-13) Ant Lord soldiers who serve Taurus Ballista and Formica Regia.
- Formica Regia-(13) The Queen Ant Lord. Destroyed by Kamen Rider Agito.
- Gelnewts-(14-15, Den-O & Decade) Newt monsters that serve Goludora and Shilubara.
- New Mole Imagin-(14-15) Mole soldiers. One is destroyed by Kamen Rider Den-O(Tsukasa).
- Coleoptera Worm Agentum-(16) A scarab monster. Destroyed by Kamen Rider TheBee.
- Geophilid Worm-(1, 16) A centipede monster. Destroyed by Kamen Rider Decade(as Kamen Rider Kuuga Pegasus Form).
- Subst Worm-(17) A crayfish monster. Destroyed by a shockwave of Mayu's transfromation of the Sisrya Worm.
- Kappa-(18) A snapping turtle/frog monster. Destroyed by Kamen Rider Deacde(as Kamen Rider Kabuto).
- Bakeneko-(18) Three cat monsters. They were destroyed by Kamen Rider Zanki, Kamen Rider Ibuki, and Kamen Rider Decade.
- Ooari-(1, 18) An ant monster.
- Tengu-(18) An ape/parrot monster. Destroyed by Kamen Rider Hibiki.
- Ubume-(1, 18) An oarfish/bird monster.
- Bakegani-(1, 18-19) A swimming crab monster. Destroyed by Kamen Rider Decade, Kamen Rider Diend, Kamen Rider Amaki, Kamen Rider Todokiri, Kamen Rider Ibuki, and Kamen Rider Zanki.
- Raydragoons-(20-21) Dragonfly monsters. They were destroyed by Kamen Rider Diend.
- Jashin 14-(22-23) A logan monster. Destroyed by Kamen Rider Deacde and kamen Rider Hibiki Armed Form.
- Darkroaches-(22-23) Cockroach soldiers. Defeated by the Riders.
- Gedoushu-(24-25) Consists of Doukoku, Tayuu, and Shitari.
- Moose Fangire-(24-25) A moose monster summoned by Chinomanako. Destroyed by Shinken Gold, Shinken Green, and Shinken Pink.
- Eagle Undead-(24-25) An eagle monster summoned by Chinomanako. Destroyed by Kamen Rider Kuuga, Shinken Blue, and Shinken Yellow.
- Shark Fangire-(1, 30) A shark monster. Destroyed by Kamen Rider Diend.
- Silkmoth Fangire-(30) A silkmoth monster. Destroyed by Kamen Rider Diend.
- Horsefly Fangire-(1, 30) A horsefly monster. Destroyed by Kamen Rider Diend.
- Warthog Fangire-(30) A warthog monster. Destroyed by Kamen Rider Decade.
- Deer Undead-(30) A deer monster. Destroyed by Kamen Rider Diend.
- Scarab Undead-(30) A scarab monster. Destroyed by Kamen Rider Diend.
- Lizard Undead-(1, 30) A lizard monster. Destroyed by Kamen Rider Diend.