Kamen Rider Double

Kamen Rider Double (aka Kamen Rider W) is the main and eponymous protagonist of the Kamen Rider Series Kamen Rider Double. Double is the first Kamen Rider that transforms from two people. His debut appearance was a cameo in the film Kamen Rider Decade: All Riders vs. Dai-Shocker. According to the producers, he was originally going to wear a trenchcoat in his henshin form, but it was decided not to include it.

Shotaro Hidari
The left half of Double providing the 'body' and a self-dubbed Hardboiled Detective. Shotaro is also a Kamen Rider on his own as Kamen Rider Joker.

Philip
The right half Double, providing the 'mind,' he disappeared after being broken down into data but came back a year later, thanks to his mother and sister.

Kamen Rider Double
When Shotaro and Philip set their Gaia Memories into the Double Driver Belt, Philip's conscious mind enters Shotaro's body to produce Double. Their quote at the start of a battle is "Now, count up your crimes!" (さあ、お前の罪を数えろ！, Saa, omae no tsumi o kazoero!), a quote originally used by Sokichi Narumi.

When combined as Double, Shotaro usually does most of the talking, though both speak when saying their pre-battle quote and announcing Maximum Drive attack names. When Philip speaks by himself when transformed, Double's right eye flashes. Double's ability to function is dependent on the condition of both Shotaro and Philip. If their synchronization is somehow disrupted, Kamen Rider Double will be unable to move properly. If their Rider form takes any damage at all, both of them will feel the pain after returning to normal and Philip will often pass out due to his weaker constitution. Shotaro's habit of flicking his wrist carries over to Double.

Kamen Rider Double is unique among Kamen Riders in that rather than having explicitly defined forms, he instead has mix-and-match powers. Through the different Gaia Memories, Double has access to various combinations of powers, weapons, strengths, and weaknesses. Kamen Rider Double's forms accessed through their first six Gaia Memories are known as Half Changes (ハーフチェンジ, Hāfu Chenji), due to the fact that Double can switch out one (or both) Gaia Memories in the belt in a Memory Change (メモリチェンジ, Memori Chenji) to change forms.

Each different version of Kamen Rider Double has its own finishing attack(s) known as Maximum Drives ( マキシマムドライブ, Makishimamu Doraibu which is needed to defeat a Dopant. The energy imparted by the Maximum Drive does not destroy the Dopant but rather its Gaia Memory, resulting in the ejection of the Gaia Memory from the user's body and the destruction of the Gaia Memory, hence why such a procedure is called a "Memory Break" (メモリブレイク, Memori Bureiku).

Double Driver
The Double Driver is Kamen Rider Double's transformation belt. It is a second generation Memory Driver after the Gaia Driver series, stolen from the Museum corporation when Philip was rescued, and uses two GaiaMemories at once for even more power for the user. There is only one, physical, Double Driver, but when Shotaro places it on him, another Double Driver manifests itself onto Philip. By inserting the GaiaMemories into the respective Memory Slots on their belt buckles, Shotaro and Philip can transform into Double. The Left Slot holds Shotaro's GaiaMemories and the Right Slot holds Philip's.

When Philip puts a GaiaMemory into the Right Slot, he undergoes Soul Forward, sending his soul to Shotaro to transform both of them into Kamen Rider Double. Another slot on the right side of the Double Driver is called the Maximum Slot. When a Memory is placed in the Maximum Slot, Double can use a Maximum Drive finisher attack. This specific slot is used for the Joker Memory to execute either the Joker Extreme (Kamen Rider Double CycloneJoker), Joker Grenade (Kamen Rider Double HeatJoker) or the Joker Strange (Kamen Rider Double LunaJoker) Maximum Drives.

In other forms, it can be used to insert the right half's Memory, allowing for a Twin Maximum attack, but this is immensely dangerous due to the strain it puts on Shotaro's body. As long as the Double Driver is worn by both Shotaro and Philip, they can telepathically communicate with each other provided that both of them are conscious outside the transformation to Double.

Gaia Memories
The Gaia Memories are mysterious USB memory sticks with imbued with the powers of the Earth itself. Originally created with funding by the Sonozaki Family, these Gaia Memories end up in the possession of Shotaro and Phillip. Compared to the Gaia Memories used by Dopants, the Memories used by Kamen Rider Double are much more refined in appearance, something that Shinkuro Isaka states is indicative of the limits placed on their powers. Two can be inserted into the Double Driver, allowing Shotaro and Phillip to transform into Double. Phillip's right-half Gaia Memories determine the elemental power of Double, while Shotaro's left-half ones determine the type of attack or weaponry that Double uses.
 * Cyclone Memory: The Cyclone Memory, also known as the Windy Memory, allows the user to move at fast speeds, controlling the very power of wind, becoming the Windy Warrior. When used, half of Kamen Rider Double becomes the Cyclonic Right Half. Forms using the Cyclone Memory possess a Wind Stabilizer, a silver scarf hanging from the neck.
 * Joker Memory: The Joker Memory, also known as the Trump Card Memory, allows the user to increase fighting potential and enhances the users reflexes significantly, becoming the Skill Warrior. When used, half of Kamen Rider Double becomes the Trumping Left Half. When the Joker Memory is placed in the Maximum Slot on the Double Driver, it enables the Maximum Drive finisher.
 * Heat Memory: The Heat Memory, also known as the Hot Memory, empowers the user with the powers of the element of fire, becoming the Blazing Warrior. When used, half of Kamen Rider Double becomes the Heated Right Half.
 * Metal Memory: The Metal Memory, also known as the Steel Memory, empowers the user with great strength and magnified resistance to physical harm, becoming the Superpowered Warrior. When used, half of Kamen Rider Double becomes the Fighting Spirit Left Half.
 * Luna Memory: The Luna Memory, also known as the Illusion Memory, allows the user to cast illusions, stretching limbs and bending gunshots, becoming the Mysterious Warrior. When used, half of Kamen Rider Double becomes the Fantastical Right Half.
 * Trigger Memory: The Trigger Memory turns the user into an expert marksman, becoming the Gun Warrior. When used, half of Kamen Rider Double becomes the Sniper Left Half. When the Trigger Memory is placed in the Maximum Slot on the TriggerMagnum, it allows Double to fire an elemental-powered Maximum Drive attack.
 * Prism Memory: The Prism Memory is a Gaia Memory for the PrismBicker sword and shield. It serves as a storage for other Gaia Memory powers and links the power of four Maximum Drives into one. Similar to the Engine Memory used by Kamen Rider Accel it is not a true Gaia Memory and its powers are linked to the Xtreme Memory.

Fang Memory
The Transforming Gaia Dinosaur Fang Memory is a special Gaia Memory that was created only to protect Philip by any means necessary, enabling him and Shotaro to transform into Kamen Rider Double FangJoker. It can change between its Live Mode, which resembles a Dromaeosaurid, and it's Memory Mode, the top of which resembles a dinosaur's head. When used, half of Kamen Rider Double becomes the white Fanged Right Half, enabling Double to fight like a berserker while altering the left half to match it in being animalistic in design. As it was created to protect Phillip it only appears when he or anyone in his vicinity is in danger. However it does appear on it's own free will during average times.

Xtreme Memory
The Transforming Gaia Bird Xtreme Memory (変形ガイア鳥エクストリームメモリ, Henkei Gaia Chō Ekustorīmu Memori?) is a special bird-like Gaia Memory that allows Kamen Rider Double to become CycloneJoker Xtreme by changing from Live Mode (ライブモード, Raibu Mōdo?) to Memory Mode (メモリモード, Memori Mōdo) in order to slide onto the DoubleDriver. It first appears when Philip is in mortal danger from being attacked by the Weather Dopant, and it digitizes him where Shroud confronts him about his mission to save the Earth. Like the Fang Memory it change between it's Live Mode and Memory Mode. To initiate its Maximum Drive, the Double Xtreme Rider Kick, the Xtreme Memory is closed and then re-opened. When Philip dissolves after his final battle as Double, the Xtreme Memory which holds the data of his mind and body does as well. It is later reformatted along with Philip due to Wakana's sacrifice.

Memory Gadgets
The Memory Gadgets are items powered by artificial Gaia Memories called Giji Memories (Pseudo Memories) that allow them to switch between their Gadget Mode and their Live Mode. The Gadgets can in turn be attached to Double's weapons to provide a boost. The Cyclone, Luna, and Heat Memories can also be inserted into a Memory Gadget, activating a Maximum Drive.
 * 141292-double_13.jpg Stag Phone is a cellular phone that switches between Cell Phone Mode and Stag Mode with the use of the Stag Memory. When in Cell Phone Mode, it allows Double to summon and control the HardBoilder and the RevolGarry. The Stag Phone also has a Maximum Drive for the Heat Memory, engulfing it in flames. When attached to the Trigger Magnum, it allows Double to perform the Trigger Stag Burst Maximum Drive, crushing the Dopant between two pincer-like energy projections. When attached to the Metal Shaft, it allows Double it preform the Metal Stag Break Maximum Drive, crushing the Dopant between two pincer-like energy projections emitted from the Metal Shaft. There are two Stag Phones, one for both Shotaro and Philip.
 * 141291-double_12.jpg Spider Shock is a wrist watch that switches between Wrist Watch Mode and Spider Mode with the use of the Spider Memory. It has a grappling hook in Wrist Watch Mode. It can also shoot out trackers which can be tracked in Wrist Watch Mode. When attached to the Trigger Magnum, it allows Double to fire out a net that can capture Dopants. When attached to the Metal Shaft, it allows Double to fire a webbed string to restrain opponents.
 * 141290-double_11.jpg Bat Shot is a digital camera that switches between Digicam Mode and Bat Mode with the use of the Bat Memory. A live video feed can be linked to the Stag Phone while in Bat Mode. Its flash can disorient others, and when attached to the Metal Shaft (a combination that Shotaro dubs the Sonic Shaft), it can emit sonic waves strong enough to shatter solid objects. The Bat Shot also has a Maximum Drive for the Luna Memory, allowing its flashes to reveal and stun any hidden targets in its vicinity. When attached to the Trigger Magnum, it allows Double to perform the Trigger Bat Shooting Maximum Drive, locking onto the target through the Bat Shot and then firing a concentrated blast from the Trigger Magnum.
 * The Frog Pod (フロッグポッド, Furoggu Poddo?) is a speaker that switches between Speaker Mode (スピーカーモード, Supīkā Mōdo?) and Frog Mode (フロッグモード, Furoggu Mōdo?) with the use of the Frog Memory (フロッグメモリ, Furoggu Memori?), which is similar to a MP3 Player that acts as a sound recorder. When the recording is played back, the Frog Pod can modulate the sound to be anyone's voice. Its primary uses are for audio recording and analysis. The Frog Memory and manual for building the Frog Pod are sent to Philip in a black envelope, by a person he believes to be Shroud, the woman who provides Kamen Rider Accel with his transformation items and arsenal.
 * The Denden Sensor (デンデンセンサー, Denden Sensā?) is a pair of night vision goggles that switches between Goggle Mode (ゴーグルモード, Gōguru Mōdo?, also translated as "Night Scope Mode") and Denden Mode (デンデンモード, Denden Mōdo?) with the use of the Denden Memory (デンデンメモリ, Denden Memori?). Its primary ability is to detect changes in the light spectrum and alert its user to possibly cloaked targets. Its Goggle Mode also serves this purpose, used to detect the presence of the invisible Lily Shirogane in its first appearance. It is also used as a surveillance device, being able to store 8 terabytes of information in its Giji Memory. The Denden Sensor is the second Memory Gadget Philip is seen constructing from a set of instructions sent to him by Shroud.

HardBoilder
The HardBoilder, designated the "MB1000RV", is Double's personal Honda CBR1000RR motorcycle. Like Double, the HardBoilder is black and green and is also able to change forms by swapping out the back half of the motorcycle after docking with the RevolGarry.

HardTurbuler
The first of HardBoilder's forms is the black and red HardTurbuler, which is a flying hovercraft-like vehicle. The HardTurbuler is armed with Scramble Cutter (スクランブルカッター, Sukuranburu Kattā) guns.The HardTurbuler is often used by Double when he is in HeatMetal form. The HardTurbuler is armed with Scramble Cutter guns. It also can combine with Kamen Rider Accel, forming the AccelTurbuler.

HardSplasher
The second of HardBoilder's forms is the black and gold HardSplasher, a personal water craft-like vehicle. The HardSplasher is armed with a torpedo launcher.

Start Dash Mode
The HardBoilder can also be put into Start Dash Mode to increase its speed. The Start Dash Mode components can be detached after deployment to slow down any chasing adversaries.

HardGunner
The HardGunner (ハードガンナー, HādoGannā?) is the combination of the front unit of the HardBoilder and Kamen Rider Accel's robotic tank the Gunner A. This combination is faster than the HardBoilder and also arms it with the Gaia Cannon.

RevolGarry
The Rotation-Interchange Base RevolGarry is a truck/garage that holds the HardBoilder and holds a revolving wheel that has the components to change the HardBoilder to the HardTurbuler and HardSplasher.

HardMammother
The HardMammother (ハードマンモシャー, Hādomanmoshā) was Double's temporarily owned giant mammoth-like mecha, piloting it when the front unit of the HardTurbuler docks into it. The HardMammother also had a Maximum Drive attack that is activated when the Heat Memory is inserted into the Maximum Slot. It only appears in Kamen Rider × Kamen Rider Double & Decade: Movie War 2010 as the Mammoth Mecha (マンモスメカ, Manmosu Meka?) under the control of Super Shocker, then Dummy Dopant control of it, before Double takes control of it. It is destroyed along with the Super Crisis Fortress.

Appearances:

 * All Episodes of Kamen Rider W (Episode 1-49).
 * Kamen Rider Decade: All Riders vs. Dai-Shocker (Cameo)
 * Kamen Rider x Kamen Rider Double and Decade Movie Wars 2010
 * Kamen Rider Double Forever: A to Z/The Gaia Memories of Fate
 * Kamen Rider × Kamen Rider OOO & Double feat. Skull: Movie War Core 
 * OOO, Den-O, All Riders: Let's Go Kamen Riders(cameo)
 * Kamen Rider W Returns (Both Accel and Eternal Portion, Cameo)
 * Kamen Rider x Kamen Rider Fourze & OOO Movie War Megamax
 * Kamen Rider X Super Sentai: Super Hero Taisen

Trivia

 * Double is the first Rider to cameo in a preceding Rider's movie.
 * Double is currently the only rider to require two people in order to transform.
 * Double Luna Metal Form's colour is similar to Kaizoku Sentai Gokaiger's hybrid of the Go-On Wings from Engine Sentai Go-Onger in that both are half gold and half silver.
 * Double Heat Trigger Form's colour is similar to Kikaider in that both are half red and half blue.
 * Double possibly has even more forms, as it is never stated that Shotaro and Phillip can't use gaia memories from Dophants, other Kamen Riders, or random Gaia Memories. This is supported by the fact that Shroud wanted to use Ryu and the Accel memory rather than Shotaro and the Joker memory to merge with Phillip and the Cyclone memory to form Kamen Rider Double CycloneAccelXtreme. In addition, Shotaro could use the lost driver used by Kamen Rider Skull to become Kamen Rider Joker, indicating that Gaia Memories aren't usable by one specific person or Memory Driver.