Worm (Kamen Rider)

The antagonists of Kamen Rider Kabuto (and made a return in Kamen Rider Decade). These creatures came from meteor of unknown origin which destroyed the city district of Shibuya seven years prior to the series' timeline (it was reveal in the movie GOD SPEED LOVE that this meteor is actually just a fragment of larger one).

Vey aggressive, Worms attempt to blend into the human population by mimicking the physical appearance of their victims along with their memories. They only need to look at the human to copy their looks, then they attempt to kill the original and copy the memories. However, the Worms believe the person that was mimicked now exists as a part of them due the fact they also acquired their victims' personalities. Despite being able to copy both look and memory, Worms are unable to copy certain things such as scent; in addition, their disguises can be neutralize by chemicals such as makeup.

Worm in pupa state is known as a Salis, taking on the shape of a Chrysalis. A Salis normally has a green body, except for the albino one known as a Mutation Salis which has a white body. When threatened or endangered, Worm has an ability to molt, revealing a stronger form that can move at blinding speeds which comes from their high metabolism. Some Worms do not need to naturally molt and their "cast" can be broken off or shattered. These Worms can revert into a Salis form if necessary. Most of Worms in molted state resemble arthropods, specifically insects. The Executives Worms are, however, resemble crustaceans and at least one mollusk Worm known to exist.

Native
There are actually another groups of Worms, the ones known as Native arrived on Earth 35 years ago. Natives usually live in peace, blending in with human society, some actually can create their own human forms without stealing other identities. At least one Native known to born naturally from Native mother. In addition, it is possible to convert human into a Native. Visually, Native in Salis state has horn on its head.

Next Worms
Exclusively appear in God Speed Love movie, these are group of Worms that came along with the third meteorite. While Next Worm in Salis form look like Native, they are much more savage and intend to conquer Earth instead of blend with humanity.

Masked Rider System
A system of small robots known a Zecters developed by Natives for the humans that would form organization known as ZECT. In return, ZECT would protect Natives from other Worms that might arrive. There are eight known Zecters within the Masked Rider System (with three more appear in alternate timeline of God Speed Love movie), each allowing the user (either human or Worm in human form) to become a different Kamen Rider. The Zecters appear instantaneously from the ZECT headquarters to the selected personnel so that they may transform into the respective Rider to fight any Worms in the vicinity. Most Rider possessed two forms such as the bulky armored cocoon-like Masked Form which can be compare to Worm in Salis state. Parts of the armor can be purged with Cast Off command to become and sleeker Rider Form. Although rarely use, Kamen Rider in Rider Form can use Put On command to rematerialise the purged armor.

In Rider Form, the Kamen Rider can use the Clock Up, a system that allows the Rider to move at high speed to match the Worms. In show, the effect of Clock Up is portrayed as the Rider (and Worm) moving at normal speed while everything else were slow-motion. In addition to enhanced physical ability, the Kamen Rider can discharge Tachyon particle, either to deliver powerful melee attack or utilise various equipments. A non-Tachyon projectile weapon is useless when fighting at Clock Up speed.

The Zecters are sentient and may leave its master on its own will.

The Zecters

 * Kabuto Zecter A Zecter based on kabutomushi, transform user into Kamen Rider Kabuto.
 * TheBee Zecter A Zecter based on wasp, transform user into Kamen Rider TheBee.
 * Drake Zecter A Zecter based on dragonfly, transform user into Kamen Rider Drake.
 * Sasword Zecter A Zecter based on scorpion, transform user into Kamen Rider Sasword.
 * Gatack Zecter A Zecter based on stag beetle, transform user into Kamen Rider Gatack.
 * Hopper Zecter Pair of Zecter based on grasshopper, transform user into Kamen Rider Kick Hopper and Kamen Rider Punch Hopper.
 * Dark Kabuto Zecter A duplication of Kabuto Zecter, transform user into Kamen Rider Kabuto.
 * Perfect Zecter A sword-like Zecter that allow the user to utilise power of several Zecters at once. Perfect Zecter can summon Drake, TheBee and Sasword Zecters and attach them to the weapon. Depending on the Zecter that is currently attached, the Perfect Zecter is capable of utilizing a hyper version of the Zecter's finishing attack in either Gun or Sword Mode.
 * Hyper Zecter A Zecter with ability to enhance other Zecter. Allow the Kamen Rider to use Hyper Clock Up ability which freeze everything in its place while the Rider using normal Clock Up will move with slow-motion. The Hyper Clock Up is even capable of time traveling.
 * Ketaros Kabutech Zecter A Zecter based on Centaurus beetle, transform user into Kamen Rider Ketaros.
 * Hercus Kabutech Zecter A Zecter based on Hercules beetle, transform user into Kamen Rider Hercus.
 * Caucasus Kabutech Zecter A Zecter based on Atlas beetle, transform user into Kamen Rider Caucasus.

Notable Worms

 * Uca Worm (Rena Mamiya)
 * Cassis Worm (Reiji Nogi)
 * Scorpio Worm (Tsurugi Kamishiro / Kamen Rider Sasword)
 * Sisyra Worm (Hiyori Kusakabe - Native)
 * Gryllus Worm (Masato Mishima - Native)
 * Souji Kusakabe (Kamen Rider Dark Kabuto - Convert human)