Alex Darwin| Kamen Rider XtremeStrong willed and optimistic, Alex shows promise in taking up the position of a Kamen Rider. Despite being an orphan, Alex always looks on the bright side of things and doesn't let small issues bring him down.
- Badass in Distress: Gets abducted alongside Madison on episode 14 by Fury.
- Cool Guns: The Corona Blaster, whose ammo changes depending on the memory it's paired with.
- Disappeared Dad: Alex doesn't seem to like him very much.
- Dreaming of Things to Come: Alex thinks this is the case with his dreams of the rider war.
- Embarrassing Nickname: Superstar, given to him by Tara.
- Meaningful Name: The name Alex literally means "defender."
- Multiform Balance: Xtreme has three base forms, each composed of two parts that can be interchanged for nine possible combinations.
- Ordinary High-School Student: Alex is a regular high school student who's just trying to get through his day-to-day life.
- Book Dumb: Alex sucks at his school work and is regularly scolded because of it.
- Transformation Trinket: The X Driver and it's 6 accompanying memories.
- It Was a Gift: It was left to him by his mother Alice and given to him by Sampson, giving it double sentimental value.
- 10-Minute Retirement: After Sarah's death.
- True Companions: Xtreme is slated to have five main riders, Alex being the first to appear.
Thea "Tara Archer" Evonna| Kamen Rider GaleAlways charging into battle with the intent to make the biggest bang possible, Tara often has a tendency to get a little carried away both on and off the battle field. She's highly artistic and is seemingly able to fly on rollar blades. With the help her best friend Kree, a small mechanical bird, she is gifted with the power of the wind and is sure to see her foes off with a graceful demise.
- A-Cup Angst
- Animal Metaphor: Tara is represented by a bird symbolizing her desire for freedom.
- Bash Brothers: After Alex retires, she and Cole become this.
- Bi the Way: She kisses Madison on the lips in episode 12 and has absolutely no issue in doing so. Madison is enraged by this action with it being her first kiss with anyone.
- Blow You Away: Has wind based abilities.
- Improbable Weapon User
- Jekyll & Hyde: Seems to have two different personalities depending on the situation.
- Must Have Caffeine: Do not keep her away from coffee, it's a bad idea.
- Rich Bitch: Averted, she is part of a rich family and does breaks the rules often as well as views herself as better than other people, but her superiority complex isn't because of her family's money.
- Robot Buddy: She has a robot bird.
- Sixth Ranger: Though she's the second rider to appear, she still shakes up the status quo.
- Transformation Trinket: Kree, alongside the Gale memory.
- True Companions: Xtreme is slated to have five main riders, Tara being the second to appear.
Cole Desmond| Kamen Rider Rock
Alex's best friend since childhood. Though he is not a rider, Cole seeks to help out Alex in anyway he can. He often picks on Alex but it's all in good fun. He doesn't start out as rider but becomes one later on in the series.
- An Axe to Grind: The Rock Smasher in Axe mode.
- Bash Brothers: After Alex retires, he and Tara become this.
- Dishing Out Dirt: Has earth based abilities.
- Nice Guy: Kindness is his main strength, and the reason Joel got interested in him.Sarah: You can't say a bad thing about anyone can you Cole?
- True Companions: Xtreme has five main riders, Cole becoming the third.
Shiore Fubuki| Kamen Rider YukiIsolated and distant, Shiore is highly skilled with a blade and is the most experienced fighter of all the riders. Though she may seem disengaged from her surroundings, Shiore always pays close attention to what's going on around her waiting until the perfect moment to strike.
- An Ice Person: Has ice based abilities.
- Animal Motifs: Wolf.
- Curtains Match the Window: Her eyes are blue like her hair.
- Doppelgänger Attack: Ice clones.
- Defrosting Ice Queen: Seems to be heading this way, after joining Alex and company.
- Emotionless Girl: Averted, though she may seem cold and heartless she still shows a wide range of emotions... but mostly anger.
- Foreign Exchange Student: From Japan.
- Highly Visible Ninja: Played with, a white armor isn't the most sltealthy of suits, but she's pretty good at dissapearing.
- Katanas Are Just Better: Her Toketsu Seishin (Frozen Spirit)
- Misplaced Retribution: She arrives to the city to take revenge on Alex... for a crime he didn't commit.
- Rei Ayanami Clone
- True Companions: Xtreme is slated to have five main riders, Shiore being the forth to appear.
- Unnatural Hair Color: Blue, strangely enough the only character with this trait.
- Unstoppable Rage: Her introduction arc displays this very well.
- You Gotta Have Blue Hair: Her unusual hair color is pointed out from time to time.
- Zettai Ryouiki: Grade B, though she wears shorts instead of a skirt.
Carter Damon| Kamen Rider Ryu-ORaised in the shadows of META, Carter is the eldest son of Rylee Damon/Spite. Though he might not speak much, he says volumes when he acts. With the gaia memory of fire in his hands, Carter displays that he is more than capable to use it's power to the fullest.
- Combat Pragmatist: Out of all the riders he is the most brutal and more determined to win.
- Mythical Motifs: Dragon.
- Playing with Fire: Has fire based abilities.
- The Dragon: Replaces Fury as this, doesn't hurt his powers and suit are based on a dragon.
- True Companions: Xtreme is slated to have five main riders, Carter being the fifth and final one to appear.
Alice Darwin| Kamen Rider FataAlex's late mother who left him the X Driver.
- Death by Origin Story: The first episode has Sampson reading off a letter written by Alice to Alex before being handed the case containing the X Driver.
- Good Mom: Though she doesn't appear in the main story, it's clear by the way people talk and how Alex acts whenever she's mentioned that she was a good person and a very loving mother.
- Mama Bear: If she was alive, she would most likely be one.
- Posthumous Character: She's died before the series started during Decade's arc she appears to Alex to cheer him on and give him his name.
- Silk Hiding Steel: She appears to be nice from how she's described, but the fact that she was once a rider makes it clear that she was more than capable of holding her own.
- The Omniscient: It's hinted that Alice could see into the future, though it's of now yet unexplained as to how she can and what the limitations are.
VaingloryThe commander of META and main villain of the series. He always lurks in the shadows, never letting on to his intentions and never showing emotion, always leaving his followers to do his dirty work. While it's unsure what his ultimate goal is, it's clear that he will do anything in order to obtain it.
- Hidden Villain: Vainglory is the only character who's true identity is not yet known. No one outside of META even knows he exists and few know what he actually looks like for he is rarely seen outside the black armor of his dopant form.
- Shoot the Dangerous Minion: He's willing to do so once Fury antics stop amusing him.
Joel Revant| InertiaA former commander of META who has since changed his ways and has seemed to have sided with the riders for an unknown reason. Intertia is a long ranged based dopant whose memory base element is shadow.
- Predecessor Villain: He was once the head of META but has long since resigned, the reason for this isn't yet known.
Derek Mavrick| FuryEver watchful, Fury acts as Vainglory's voice of logic and is a master strategist. While some might claim that Fury is a coward for not going on the offensive, Fury simply views such tactics as ineffective preferring to have his henchmen do the dirty work while he sits safe from harm. Only when there is no other option, Fury will take matters into his own hands when his grunts fail in their missions.
- Bloodbath Villain Origin: In episode 21 it's revealed that his entire family was taken honest and killed one by one when he was just a boy. He eventually broke free and killed his captures, afterwards he realized that he enjoyed the sensation of killing others and craved it to the point of insanity.
- Breakout Villain: Was originally meant to be killed off early on in Act Two but due to an unexpected fan base he has his role expected and became the major villain for a good chunk of acts two and three... kind of.
- Healing Factor: His gaia memory gives him the power to regenerate instantly. As Carter shows, it has it's limits.
- Mid-Season Upgrade: Ruthless Fury.
- Punch-Clock Villain: He views himself as a business man and a "creator of fine art".
- The Dragon: Though his loyalty to META is questionable, he had no qualms with putting the riders through their fair share of distress.
- Third Eye: Fury's dopant form has a lizard like eye in the center of his hood and two others on his shoulder armor which make the first thing they all catch in the line of sight explode. His actual eyes cannot be seen.
Rylee Damon| SpiteEver vigilante, Spite acts as Vainglory's voice of reason. Though some of her missions haven't exactly gone according to plan, she vows to return and correct her errors and put her foes in their place and ensures that they remember who it was that put them there.
- Even Evil Has Loved Ones: She shows genuine concern for her son Carter despite her display of complete loyalty to Vainglory.
- Punch-Clock Villain: She works for Vainglory and META. Whether she's truly evil is not yet known.
Cheshire| GorgeRylee's pet cat.
- Right-Hand Cat: For Rylee
Gordon SampsonChief of the Ardent City Police Department. Sampson acts as Alex's mentor. It's hinted that he was once good friends with Alex's mother.
- A Father to His Men: He genuinely cares about Alex and company.
- Reasonable Authority Figure: Despite being a cop, he understands that Riders are better fit to fight dopants.
Johnathan MarcohSampson's second in command. He's a very by the books police officer with very little patience. Though he is rather understanding of the personal issues of others, he has no problem calling them out when the make a mistake.
- Jerk with a Heart of Gold: While he may come as abrassive from time to time, he always has good intentions.
Madison TylerA classmate of Alex and Cole. Though she mostly remains quiet, she has an undying love for Power Rangers and Anime, more specifically Ninja Storm and Puella Magi Madoka Magica. Over time she develops a crush on Alex and tries on multiple occasions to confess her feelings but various things keep getting in the way of her doing so.
- Ascended Extra: Was only meant to appear as a one off friend of Sarah but had her role expanded, causing the storyline of the series to be dramatically altered.
- Cannot Spit It Out: Whenever she tries to ask Alex out, either a Dopant attacks, or another unexpected event happens. She is however able to spit it out after some questionable coaching methods from Tara.
- Damsel in Distress: Gets abducted alongside Alex on episode 14 by Fury.
- Embarrassing Nickname: Mad Pad, given to her by Sarah.
- First Kiss: With Tara out of all people, she isn't pleased with it.
- Shrinking Violet: Though not entirely gutless, she's pretty damn close.
Sarah Gardner| ReptilianA classmate of Alex as well as the student council president and star runner of the school's track team.
- Alpha Bitch: Averted, though she can get rather annoyed by Alex's constant idiocy, she still treats as a valued friend.
- Ascended Extra: Was only meant to appear as a one off character but had her role expanded, causing the storyline of the series to be dramatically altered. According to Word of God she (along with Madison) wasn't even present in the original draft of the story.
- Cool Big Sis: To Madison, though they're not actually related by blood.
Andrew Dekerman| ScamA Gaia Memory dealer that Cole and Tara tracked to get info on Fury.
Ashley "Ash" Haze| ShiftA student at Alex's school and a friend of Sarah and Madison. She was given a gaia memory and became a thief to support her family. Though she was hostile towards Alex at first, the two were able to reach an understanding by the end of episode 7 and it's hinted that after the end of her arc that she was put on the round to recovery.Shift is a long ranged based dopant whose memory base element is water.
- Phantom Thief: She is able to phase through any solid object/surface like a ghost.
- The Bus Came Back: To help Alex get out of his depression.
- Elemental Powers: She has control over any body of water.
Greg Walker| ShredderA psychopathic serial killer that was put in jail ten years before the start of the series. Shredder is an offense based dopant whose memory base element is steel.
- Serial Killer: He killed Alex's mother and many others before in the past just to get by in life.
Mikey Crater| MinorAn agent of META. Mikey is an offense based dopant whose memory base element is light.
- Like Brother and Sister: Literally: Younger brother of Zix/Major.
- Sibling Yin-Yang: Minor is based in offensive tactics, while Major is based in defensive.
Roy Lawrence| FlameAn agent of META. Flame is a offense based dopant whose memory base element is fire.
- Everyone Calls Him Flame: Roy's actual name is never said in the series itself, instead being referred to by the name of his gaia memory.
Zix Crater| MajorAn agent of META. Zix is a defense based dopant whose memory base element is light.
- Like Brother and Sister: Literally: Older sister of Mikey/Minor.
- Sibling Yin-Yang: Major is based in defensive tactics, while Minor is based in offensive.
Marika Sakai| Kamen Rider MagicaA magic themed rider that Alex teamed up with in the crossover special "Movie Taisen:Zeta"
Tsukasa Kadoya| Kamen Rider DecadeA Kamen Rider that travels between worlds, once he arrives to Ardent City he joins Alex in his fight against the Glitch Dopant, only to attack the Riders afterwards after seeing them as unfit.
- Finishing Move: Because Decade can transform into past Riders, he can also use their finishing attacks.
- Power Copying: His entire theme, being able to transform into any of the nine previous Heisei Rider heroes.
- Undead Tax Exemption: Every time he enters a parallel world, he's assigned a role that helps him solve the current crisis.
- Weapon of Choice: The Ride Booker holds Decade's cards and can turn into a sword or a gun.
Daiki Kaito| Kamen Rider DiendA famous thief that targets the greatest tresures of different worlds, he arrives to Ardent City to steal an special artifact (The Xtreme Gaia Memory) from the police.
Yuusuke Onodera| Kamen Rider KuugaOne of Tsukasa's friends and originally the main Rider of his home world, while not the original Kuuga, he has proved time and time again his worth.
- For Happiness: As with Godai, his motivation is to protect everyone's smiles.
Natsume Hikari| Kamen Rider KivaraTsukasa's oldest friend, she played a key part in Decade's journey, predicting the Rider War and eventually becoming Kamen Rider Kivara.
- Cool Sword: Kivala Saber
- Finger Poke of Doom: The Hikari Secret Laughing Pressure Point, which she mostly uses on Tsukasa when he does or says something rude.
- Finishing Move: Sonic Stab