Sonic the Hedgehog
- Blow You Away: He has an attack called Whirlwind, which hits all foes with wind damage, and a variation called Triple Tornado, which includes Knuckles and Tails.
- Did You Just Punch Out Cthulhu?: Several. Shadow, Ix (twice), the upper Zoah leadership, and that's just in this game.
- Fragile Speedster: Like always, he is very fast, tied for the most attacks per round in the game, but he has low armor, meaning he cannot take many hits.
- In-Series Nickname: Rouge calls him "Big Blue".
- Took a Level in Jerkass: If you select the more snarky options in a Dialogue Tree.
Miles "Tails" Prower
- Always Someone Better: If Cream is obtained. He is quite weak and only has average speed. Cream is far better at healing and Amy and Rouge can weaken the enemy without him. Even in the field, Cream can fly just as well as he can.
- Big Damn Heroes: When Sonic and Knuckles are being overwhelmed by Marauders, he and Eggman show up with a (non-lethal) weapon that teleports the enemy away.
- Squishy Wizard: He cannot do much damage on his own, but his skills are useful for increasing the damage done by his teammates, and in turn relies on them to keep him safe.
- Support Party Member: Tails' POW moves allow him buff or debuff. He doesn't have a single POW attack.
- Combat Pragmatist: She has a move called Low Blow, which hits the weak spot on the enemy and makes them vulnerable.
- Drop the Hammer: Amy's trademark weapon is her Piko Piko Hammer.
- Panty Shot: When running in the overworld.
Rouge the Bat
- Armor-Piercing Attack: The Jewel Storm POW move. Rouge will throw many fake jewels that will affect multiple enemies. Too bad the damage is low even at maximum level.
- Deadpan Snarker: As always, Rouge has a sharp tongue.
- Spoony Bard: Rouge is quite weak and fragile, only has average speed, has decent special attacks, and has no exclusive field moves useful in more than one area. However, she has a very useful skill which allows her to steal items from enemies, giving her team an unlimited supply. She is also necessary for powerful combos.
Big the Cat
- The Ditz
- Draw Aggro: His taunt move will incite a single enemy to fight him and him only.
- Improvised Weapon: Big use his fishing rod as a weapon.
- Stone Wall: Has the most health on his team, but his low speed and only average strength prevents him from doing much offensively.
- Took a Level in Dumbass: From previous games. There, he is a bit of a Ditz, but he has basic common sense. Here, he asks for ice cream when the team is thinking of a plan.
Knuckles the Echidna
- Armor-Piercing Attack: His uppercut bypass enemies' armor for a huge damage.
- Cutscene Power to the Max: In his escape cutscene, he one-shots two Elite Mooks. It is very difficult to do so in gameplay.
- Dishing Out Dirt: His Quake Punch deals Earth damage.
- Irony: For a guy who prefer to work alone, 4 out of his 6 POW moves require a teammate. Tails, Cream and Big are the only characters without their own team POW move.
- Lightning Bruiser: More "bruiser" than "lightning", but his speed is nothing to laugh at, as he usually attacks before anybody, save for Sonic and Shadow.
- Meaningful Name: Besides the more obvious spikes from his knuckles, Sonic Chronicles revealed that his ancestors were called the "Knuckles Clan", meaning that our Knuckles is actually named for his ancestors' tribe.
- Redundant Rescue: When the heroes finally arrive at his prison, he has already broken out.
- Ship Tease: With Shade. They are the last surviving members of their race (who aren't evil) and show concern for each other. Lampshaded by Rouge.Rouge: So, you've always been into older women, eh, Knuckles? note
Dr. Ivo "Eggman" Robotnik
- The Chessmaster: He anticipated that he would be defeated during his fight on his Egg Carrier and planned ahead by calling a Med Bot to pull him from the wreckage and nurse him to health. He also took full advantage of the Nocturnus Clan invasion by pretending that he had undergone a HeelFace Turn and helped Sonic and co. along until they left for the Twilight Cage. Knowing full well about the Twilight Cage's Year Outside, Hour Inside properties, he used the time to rebuild Metropolis and build up his army. And thanks to the game's Cliffhanger ending, he practically won!
- A Taste of Power: He has high health and POW move points, an easy-to-use and ridiculously powerful attack that hits the entire opposing side, and can insta-kill enemy robots with Tails. You only get him for two chapters.
Shadow the Hedgehog
- Anti-Hero: As always.
- Anti-Villain: Fought Sonic and his friends at first. However, it was revealed later that his true motive was to help Omega.
- Aloof Ally: In the Twilight Cage, if he is not in your party, you will hear people saying they saw Sonic running around "like a shadow". Talking to him after this will reveal that yes, he was doing it, and you can either tell him OK as long as he's ready when they need him, or no, you can't continue. It doesn't affect anything gameplay-wise.
- Berserk Button: Accusing him of things he didn't do. As seen in Sonic Chronicles, he didn't take Sonic and his friends assuming he was up to something bad very well, and assumed that they were trying to start a fight with him (which would result in a fight if the player chooses to make Sonic willing to fight him).
- Characterization Marches On: In Sonic the Hedgehog (2006), Shadow stated "There's no strength in numbers!", while fighting Mephiles's clones. In Sonic Chronicles, he seemed to have changed his mind, as when he teams up with Sonic and his friends, his response was "Strength in numbers, right?".
- Deadpan Snarker: Has his dry and sarcastic sense of humor as usually.
- Kamehame Hadouken: Can perform a different version of the Chaos Blast in Sonic Chronicles that enables him to fire beams of concentrated Chaos Energy from his hands. He's capable of combining it with Omega's machine guns as well.
- Lightning Bruiser: Tied for most attacks per round and deals high damage with his Chaos abilities.
- Not So Different: While he and the heroes fight at first, later you realize he has similar goals that Sonic had: to rescue a powerful friend who has been captured by the Nocturnus.
Shade the Echidna
- "Please, I wish for a chance to prove myself, my new friend."
Introduced as the commander of a mysterious group of warriors called the Marauders. Turns out the "Marauders" are in actuality the long-lost Nocturnus Clan. Shade wants to help the clan return to their homeworld, but when her boss explains that he intends to conquer the world, she objects and joins Sonic's side.
- Anti Villainess: At first...
- Authority Equals Asskicking: She stands out as the toughest warrior of the Nocturnus Clan.
- The Atoner: One half of the reason for her HeelFace Turn—see below for the other.
- Badass Adorable: When not wearing her helmet.
- Dark Action Girl: While working for Ix.
- Expy: Julie-Su: A member of a lost tribe of Echidnas known as the Dark Legion from the Archie Comics shares a lot of similarities with Shade. And the entire Nocturnus share similarities with the Dark Legion from the same comics. The most obvious example, in the comics the Dark Legion was sealed away in the Twilight Zone, while the Nocturnus were sealed away in the Twilight Cage. Both were alternate dimensions that seem like pretty terrible places to be. Word of God says this is intentional...which turned out to be a massive mistake, as it was what spurred Ken Penders on his lawsuit rampages that ultimately brought down the Archie comics.
- Girl of the Week: She is suggested to be this to Knuckles by other characters, given they are the opposite sex and the last of their kind(ish).
- Glass Cannon: Ironically, as she is the only organic team member who wears armour. Subverted when she uses her cloak skill.
- Helmets Are Hardly Heroic: She takes her helmet off earlier on in the game for The Reveal, but when she swaps sides she ditches it for good.
- High-HeelFace Turn: Well... pretty close. She's the only girl of the Nocturnus Clan we see, but we see other male echidnas oppose Ix as well.
- Knight Templar: She sincerely wants to help her people escape the Twilight Cage and to that end she follows Ix's orders completely, even if it means hurting others. Subverted however when he reveals his true intentions for Earth.
- Laser Blade: Her Leech Blades.
- Lightning Bruiser: Her cloak skill greatly increases her speed and makes her impossible to hit.
- Ms. Exposition: Most of her dialogue is exposition dumps about Ix and the Nocturnus clan.
- Not What I Signed on For: She wished to return her clan to the outside world. When Ix let slip his plans to conquer said world, she turned against him.
- Put on a Bus: While a sequel to Chronicles was supposedly in the works, it was put on hold when Ken Penders took offence at the Nocturnous and their similarity to his own Dark Legion, resulting in a lawsuit that wiped those characters from the comic canon and added Shade to the "Can, but Won't Use" list, alongside characters like Mephiles.
- Really 700 Years Old: Found out in a conversation branch in the start of Chapter 6 that she's really 4000 years old. Due to the Year Inside, Hour Outside physics of the Twilight Cage, however, she is likely not much older than the others physically.
- The Stoic: Somewhat; she's friendly enough with her comrades, but not exactly emotive.
- Teleporters and Transporters: Her Warp Belt, which allows her to temporary leave the Twilight Cage and teleport from place to place.
- There Is Another
- Throw Down the Bomblet: During her Echidna Rush move with Knuckles.
- Undying Loyalty: To Ix. Until he reveals his true intentions for Earth.
- Well-Intentioned Extremist: She merely wants her people to return to Earth, though she abides by Ix's rather ruthless measures for doing so, going through with his invasion plans and brutal attempted execution of Sonic and Knuckles directly before he reveals his not-so well-intentioned after-plans.
- What Happened to the Mouse?: If one subscribes to the hypothetical placement of the game as right before the "untold adventure" briefly shown directly at the beginning of Unleashed (and considering Chronicles' reputation and the resultant lawsuit, that's a bit of a stretch), her absence in the series is virtually the only loose end.
Cream the Rabbit
- Optional Party Member: Either you let her tag along or not is up to you.
- Squishy Wizard: Even more so than Tails.
- Support Party Member: All her POW moves are curatives except for one move that cause a debuff on an enemy.
- Adaptational Jerkass: Omega in Chronicles acts more like an HK-47 Expy instead of the Strength Equals Worthiness modus operandi battle robot in the games.
- Armor-Piercing Attack: The beam cannon punch straight into enemies' defense for massive damage.
- Badass in Distress: Similar to Knuckles. However, as a robot, he can be shut down, so he could not escape.
- Crippling Overspecialization: He is insanely strong and resilient. He is however, one of the slowest in the game.
- Energy Weapon: The Beam Canon.
- Foil: To Knuckles. Both are powerful fighters who were captured by the Nocturnus. However, Knuckles, being organic, could not be shut down and escaped while Omega, a robot, was shut down after his defeat and could not escape on his own.
- Mighty Glacier: Only attacks once per round, but that one attack deals massive damage, and deals half of that damage to the enemies surrounding the one the attack hits.
- More Dakka: Firing his machine guns at full auto and at close range. Ouch!
- Optional Party Member: Shadow will ask you to look for him, but you can refuse to hire him.
- Aliens Speaking English: The Kron, N'rrgal, and Zoah speak, though the Kron talk like Yoda and the N'rrgal talk like snakes. The Voxai speak telepathically, so it may just be heard in the listeners' native language.
The long-lost nation of echidnas led by Imperator Ix.
- Expy: Of the Dark Legion, being that both are a race of echidnas with high-tech weapons.
- Lost Technology: Chronicles reveals that the Nocturnus echidna clan created the Gizoid technology, including Emerl.
- Greater-Scope Villain: They instigated a war with Pachacamac's Echidna tribe which drove the latter to try and steal the Chaos Emeralds, and unwittingly caused Chaos to be consumed by vengeance. They also created Emerl, making them responsible for the events of Sonic Adventure and Sonic Battle respectively.
- Duel Boss: He fights Sonic one-on-one.
- The Dragon: To General Raxos.
- Nice Job Fixing It, Villain!: They would have defeated Sonic had they not released his friends from their control.
- Co-Dragons: With Charyb to Ix.
- Playing with Fire: His main method of attack is to throw a fireball at his opponent.
- Co-Dragons: With Scylla to Ix.
- Hopeless Boss Fight: When you first fight him, it is impossible to deal more than 2 damage. After three rounds of getting curbstomped, you switch to the other team and make him beatable.
- "I have been imprisoned in the Twilight Cage for too long! Soon I will break free and shake the foundation of the universe!"
The leader of the Nocturnus Clan and the final boss.
- And I Must Scream: He's been trapped in the Twilight Cage for 4000 years, unable to age due to its Year Outside, Hour Inside properties.
- All There in the Manual: His full name, Pir'Oth Ix, was only mentioned on the game's website.
- Authority Equals Asskicking: He's considerably older than most of the cast, but he's also the one in charge and it shows in battle.
- Badass Bookworm: Incredibly smart, a skilled manipulator, and more than capable of holding his own in a fight.
- Big Bad: In Sonic Chronicles.
- Blood Knight: His response when fighting Super Sonic? He calls him a worthy opponent.
- Broken Pedestal: For Shade, who swears off all loyalty to him when he reveals his true intentions for Earth.
- Colony Drop: At the end of chapter 5, he takes the Master Emerald into the Twilight Cage, causing Angel Island to crush Metropolis.
- Dimension Lord
- Dub Name Change: His name was changed for the Japanese release to "Novem". Likewise, Super Ix is renamed as "Serious Novem"
- Duel Boss: He fights Super Sonic one-on-one.
- Energy Ball: His Doom Orb.
- Evil Albino: Has albino fur.
- Evil Overlord
- Expy: A white technology-using echidna as a villain? Sounds like Dr. Finitevus and/or Dr. Zachary to anyone?
- Fantastic Nuke: His Overload attack as Super Ix.
- Final-Exam Boss: The last battle with Ix tests to see how good you are with the Action Commands. And the one right before it checks your skill at the fleeing/catch-the-fleeing-enemies minigame.
- Frickin' Laser Beams: He can fire them from his staff.
- Fully Dressed Cartoon Animal: He even wears a big hat.
- Go Mad from the Isolation: Shade points out that years in the Twilight Cage has driven Ix insane.
- Graceful Loser: He takes his defeat at Sonic's hands quite well before deciding to close the portal to the Twilight Cage and trap them with him.
- Greater-Scope Villain:
- Of Sonic Adventure. If Ix hadn't instigated a war with Pachacamac's Echidna tribe which drove the latter to try and steal the Chaos Emeralds, and unwittingly caused Chaos to be consumed by vengeance, then the events of Sonic Adventure wouldn't have happened as we know it.
- As well as Sonic Battle. If it wasn't for his Nocturnus Clan creating Emerl then the events of Sonic Battle would never happen.
- Knight of Cerebus: For Knuckles, much like Black Doom is for Shadow.
- Power Floats: In cutscenes only. In game, he'll run.
- Recurring Boss: Fought three times throughout the game.
- Staff of Authority: And it's not just for show. Interestingly, his staff resembles the Jeweled Scepter.
- Taking You with Me: When beaten for the final time, he decides to close the wormhole to ensure Sonic and his friends would be trapped in the Twilight Cage with them.
- Tragic Villain: It's implied he wasn't always so evil, and mainly became this way due to spending centuries trapped in the Twilight Cage.
- Unwitting Instigator of Doom: His war with Pachacamac's Echidna tribe is part of what drove the latter to try and steal the Chaos Emeralds, and unwittingly caused Chaos to be consumed by vengeance and nearly drive the Echidna race (the ones on earth) to near-extinction.
- Villain Ball: Ix, was it really a good idea to shout your plans for world domination in front of your loyal Dragon?
- Villainous Valor: Despite being beaten twice by the team, Ix continues to fight, and even when confonted by Super Sonic, he doesn't flinch and fights Sonic with everything he has.
- Villain of the Week: The main threat of Sonic Chronicles, his only appearance.
- We Can Rule Together: He tries to offer this to Knuckles. It ends as well as you'd expect.