The protagonist, Sonic was raised in a middle-class home. He is a super-fast hedgehog capable of exceeding the speed of sound. Sonic has a laid-back, wisecracking personality but dislikes evil.
- Adorkable: He has his moments.
- Beware the Silly Ones: He's the least focused and (usually) the least serious of the three, but also the one who causes the most havoc with Robotnik's plans.
- Big Eater: As with most adaptations, he is usually seen scarfing down on many chili dogs.
- The Cynic: Sometimes.
- Envy: Got this towards Knuckles when Manic complemented his skills.
- Jerk with a Heart of Gold: As per his pre-Adventure characterization, Sonic is a slightly caustic Deadpan Snarker but seriously cares about Mobius and his siblings and is determined to see Robotnik fall.
- Pink Girl, Blue Boy: The Blue Boy to Sonia's Pink Girl.
Manic is the lovable brother of Sonic, and was raised as a thief. He is a punk rocker and a talented drummer. He will always risk his life to save Sonic before himself.
- Anime Hair: Arguably the most wild of any Sonic character: it's green and sticks up all over the place at odd angles.
- The Artful Dodger: Was raised by thieves (who stole him from a doorstop, no less), and has trouble packing the habit in after reuniting with his siblings.
- Badass Adorable: Wears his heart on his sleeve a lot more than Sonic, and almost as much as Sonia.
- Badass Normal: While Sonic has his Super Speed, and Sonia has her Super Strength, Manic only has his lock-picking ability and his Hover Board to get him by.
- Beware the Nice Ones: He's a fun-loving, humble person, but doesn't hesitate to fight against villains.
- Deadpan Snarker: To a lesser extent than his brother, but still there.
- Despair Event Horizon: Teeters on it on a couple of occasions, most notably in "The Art of Destruction", when he notes that their actions aren't having any lasting effect on Robotnik's empire and starts to wonder why they're even trying.
- Dishing Out Dirt: His drumkit can cause earthquakes.
- Drives Like Crazy: Downplayed, but in one episode, his siblings complain that he seems to be hitting every pothole on the road.
- Hover Board: Has a red-and-yellow one that appears to be able to fly indefinitely with no need for fuel.
- Lovable Rogue: He's a thief, but otherwise a good guy.
- Mr. Vice Guy: He just can't stop stealing things.
- Nonindicative Name: Generally the most laid-back of the trio.
- Surfer Dude: Hover Board? Check. Messy hair and earrings? Check. Totally Radical lingo? Crashin', dude.
- You Gotta Have Blue Hair: As a match for his punk style.
The sister of Sonic and Manic, Sonia was raised in the aristocracy and can be self-centered at times. She rides a motorcycle and has a crush on Knuckles.
- Badass Biker: Rides a pink-and-purple motorbike, and is quite skilled at driving it. It gets destroyed in one episode after crashing into a wall.
- Bound and Gagged: In "Dunes Day", after discovering that Ifyoucan was roboticized.
- Character Development: Initially Sonia was spoiled and prone to complaining whenever her appearance was tarnished. Later in the series, she becomes more of a leader figure, and is easily the most focused of the siblings.
- Deadpan Snarker: Just like her siblings.
- '80s Hair: She basically has a pink mohawk.
- Everything's Better with Spinning: Can spin rapidly in a tornado-like attack.
- Fallen Princess: Represented the upper-class part of the trio.
- Furry Female Mane: She has pink hair. It's not stylized quills like Amy's.
- Interspecies Romance: With Knuckles (an echidna), Cyrus (a lion) and also Bartleby (a mink).
- Photographic Memory: Brags of having this in one episode. Cue Sonic and Manic posing for a photo. Ironically, she suffers Laser-Guided Amnesia in one episode.
- Pink Girl, Blue Boy: The Pink Girl to Sonic's Blue Boy.
- Pint-Sized Powerhouse: Slightly shorter than her siblings but has Super Strength, able to lift and throw Dingo, who is at least twice her size.
- Spoiled Brat: Due to being raised in the aristocracy, it took a while to get used to being a homeless fugitive.
- Super Strength: In one episode, she's able to pick up and throw Dingo.
- Tomboy with a Girly Streak: Was raised as a prim and proper lady, but was also pretty sporty even before her foster mother's capture.
Knuckles is the guardian of one of the Chaos Emeralds, and lives on the Floating Island. He is a loner who is destined to his duty but is well-mannered and believes in the good of people.
- Aloof Ally: Prefers to work by himself, and in "Chaos Emerald Chaos" the triplets have to sing one of their trademark Aesop-y songs before he's willing to work with them.
- Big Damn Heroes. He saved Sonic, Manic & Sonia on his own from Dr. Robotnik and his robots, and set them free.
- Dreadlock Warrior: As always.
- Interspecies Romance: With Sonia (a hedgehog).
- It's All My Fault: This is his reaction after Dr. Robotnik successfully tricks him and steals his Chaos Emerald.
- HeelFace Turn: After his first encounter, having realized that the triplets aren't the real threat.
- Hot-Blooded: After Sleet and Dingo convince him that the triplets are out to steal his Chaos Emerald, he pursues them relentlessly and aggressively.
- Married to the Job: While he doesn't seem to be the Last of His Kind, as in other media, he's still duty-bound to guard the Chaos Emerald on Floating Island. In "Chaos Emerald Chaos" it takes a lot of persuading for him to leave the island despite the danger posed by the broken Chaos Emerald.
- Red Is Heroic: His dreadlocks are red and he's a big hero.
- Team Pet: In his first appearance he had a pet dinosaur named Chomps.
- Undying Loyalty: To his job as guardian of the Chaos Emerald, and later, to the triplets and their cause.
Dr. Robotnik is the evil dictator of Mobius, and the boss of Sleet and Dingo.
- Adaptational Badass: Despite the occasional Butt-Monkey moment, this is still one of his most competent and sinister portrayals. He rules Mobius with an iron fist and is an ever-present threat to the hedgehogs, to the point that in "The Art of Destruction", Manic starts to wonder if there's any point in fighting him.
- Would Hurt a Child: Though he is depicted as a bumbling villain, one of his goals is to find Sanctuary - where Freedom Fighters hide their children - and exterminate all the children in it.
The intelligent wolf minion of Dr. Robotnik and partner in crime of Dingo.
- Anime Hair: Blue and spiky.
- Deadpan Snarker: His remarks tend to go over Dingo's head.
- Evil Genius: Sleet generally makes plans that, at least on paper, are sound. It's usually Dingo's incompetence or Sonic's meddling that causes these plans to go off the rails. At the very least, Sleet is able to keep convincing Robotnik that he shouldn't roboticize them, in spite of their constant failures.
- Expy: Part of a pair of villainous lackeys much in the proud tradition of Scratch and Grounder. Specifically, Sleet is thin and ostentatiously the smart one, like Scratch.
- Fangs Are Evil: Like Dingo, he has a pair that are very noticeable when he's grinning.
- Fat and Skinny: With Dingo. Sleet is straight-up skinny.
- Faux Affably Evil: Despite being the butt of occasional jokes, Sleet can be a very sinister and effective villain when he tries. On one occasion, he obtains information from a tipster, who he then immediately has roboticized.
- Laughably Evil: Prone to being a Butt-Monkey.
- Pet the Dog: Despite how terribly Sleet usually treats his own partner, in Episode 39, Dingo asks Sleet for a break, and Sleet agrees.
- The Starscream: Attempted in the three-parter, together with Dingo: they steal the Chaos Emerald from the Flying Fortress, intending to use it to overthrow Robotnik and rule Mobius. Dingo then steals it from Sleet... and promptly drops it.
- Those Two Bad Guys: Together with Dingo.
- You Gotta Have Blue Hair: Navy blue, in this case.
The dim-witted minion of Dr. Robotnik and partner in crime of Sleet. He can shapeshift using a remote.
- Affably Evil: Dingo seems largely unaware of what is going on most of the time and just seems to be along for the ride.
- Almighty Idiot: At one point Dingo absorbs a Chaos Emerald and mutates into a enormous blob monster that threatens to destroy the planet.
- Anime Hair: It's very spiky.
- Baleful Polymorph: Dingo tends to be at least a little bit surprised when Sleet forces him to transform using the remote control. He's especially annoyed when he's forced to transform into a boat.
- The Brute: In contrast to Sleet's Evil Genius.
- Butt-Monkey: Constantly falls over something.
- Dumb Muscle: Strong enough to break through walls, and dumb enough to do so after mistaking a sarcastic remark for a genuine order. According to Sleet, he can't even drink a glass of water without using both hands.Dingo: Maybe not, but I don't spill as much as I used to.
- Expy: Part of a pair of villainous lackeys, in the proud tradition of Scratch and Grounder. Specifically, Dingo is dumber and squat, but can do a wide variety of things thanks to his ability to transform, somewhat like Grounder.
- Fangs Are Evil: Has a pair that are most noticeable when he's grinning.
- Fat and Skinny: Dingo isn't fat, just very muscular, but he and Sleet still fit this trope.
- Ineffectual Sympathetic Villain: Dingo cannot even follow directions to go through a door properly. Most of the duo's failures are because Dingo screws up, gets distracted, or simply has bad luck. For example, Dingo very nearly gets away with Angel Island's Chaos Emerald, only to trip, fall, and send it tumbling away. Sleet is very eager to call him an "EEDiot" for his fumbles.
- Laughably Evil: Due to being a clumsy moron.
- Lennon Specs: Unusually for somebody filling the role of Dumb Muscle, Dingo's got some.
- The Starscream: Attempted in the "Flying Fortress" three-parter: after he and Sleet steal the Chaos Emerald from the Flying Fortress, Dingo steals it from Sleet, intending to rule Mobius himself. He then drops the Chaos Emerald and breaks it.
- Those Two Bad Guys: With Sleet.
- Top-Heavy Guy: His upper half is twice as wide as his lower half.
- Villainous Crush: Dingo has a crush on Sonia, which she occasionally uses to her advantage.
The mother of the royal triplets. Aleena was usurped from her throne and lives in hiding until the prophesied moment, occasionally helping her children from afar.
- Action Mom: Occasionally, most prominently in "Sonia's Choice" where she flies in piloting a freaking gunship, destroys several SWAT-bots, and rescues Manic.
- Cool Crown: It even has a special jewel that can track her if separated from her.
- The High Queen: Or at least, she was before Robotnik deposed her.
- In the Hood: Wears a cloak most of the time.
- Mama Bear: Though the prophecy forbids her from reuniting with her children until the right moment, she does show up to save them more than once.
- Rapunzel Hair: It's very long, albeit hidden behind her cloak most of the time.
AthairKnuckles' grandfather, who originated from the Archie comics. He gives the young echidna advice on occasion.
The Oracle of DelphiusA reptilian mage, the Oracle mentors the triplets, though not always in a straightforward manner. He learned of the ancient prophecy and warned both Aleena and Robotnik about it, setting the events of the series in motion.
- Trickster Mentor: He almost never gives a straight answer, and many of his challenges have hidden meanings or solutions.
Bartleby MontClairAn aristocratic mink and Sonia's ex-fiance. Bartleby is very haughty and is often cowed into paying Robotnik tribute, but helps the hedgehogs on occasion.
Mindy LaTourAn aristocractic fox and old friend of Sonia's, she is unwittingly involved in one of Robotnik's schemes when her father helps distribute watches that watch people.
- Defector from Decadence: She and her father join the Resistance once Robotnik's plot is discovered, leaving behind their lavish lifestyle.