A blue hedgehog who can run at supersonic speeds. He, his friends, and Dr. Eggman are transported to Earth by a blast of Chaos Control. Sonic, Tails, Amy Rose, Cream and Cheese live in secret with Chris Thorndyke and his family, though their presence is eventually discovered. Sonic acts as a bit of an Aloof Ally, often pulling Big Damn Heroes moments Once per Episode. Can transform into Super Sonic when he possesses the Chaos Emeralds.
The Ace: Leans more as this as the show progresses, especially due to his more one dimentional role and the majority of the cast's idolization of him.
Ace Pilot: Proved to be this when he flew the X-Tornado.
Always Someone Better: A lot of characters convey an animosity towards him because of his bravado and popularity, Eggman, Knuckles and the Chaotix in particular have recurring jealous rivalries towards him.
An Odd Place To Sleep: Has a tendency to sleep on rooftops, balcony guards, the wing of the X-Tornado and even on top of a castle battlement in one instance.
Creepy Monotone: His voice becomes this when he becomes "Dark Super Sonic", right before tearing the two Gold and Silver Metarex new ones. The sheer difference between his normal voice and this voice is extremely creepy
Hero with Bad Publicity: Along with his friends, he initially gets in trouble with the authorities and hides out in Chris' house when not countering Eggman's latest scheme for the early part of Season 1.
Only Sane Man: In the episodes "Sunblock Solution" and "Eggman for President," he's initially the only person who realizes that Eggman's Egg Moon/Sunshine Ball deal is a scam and a lie because if the Egg Moon had truly stopped rotating, then it would stand still and not keep blocking the sun. When he goes about destroying the Sunshine Balls, even Sonic's pals think he's gone bad until he point-blank tells them as such.
An eight-year old fox with two tails, Miles "Tails" Prower is Sonic's best friend. He is a pilot, mechanic, inventor and sidekick to Sonic. While humble and sees Sonic as his idol, Tails grows to become independent and forms a Intergenerational Friendship with Chuck. He pilots the Tornado bi-plane, and then the X Tornado. Forms a romantic relationship with Cosmo in the third season.
Demoted to Extra: To an extent. His role as Sonic's right hand man is seen a lot less in favor of the latter's bond with Chris. He gains a more prominant role in the third season however and the comics also use his sidekick role more often.
The Everyman: Despite his genius intellect and occasional Cheerful Child traits, he is mostly little more than the Nice Guy of the group. He is developed slightly in the third season, though it's still kinda hard to define his personality.
Sonic's friendly rival, Knuckles is the guardian of Angel Island and the Master Emerald. Completely focused on his duty to guard the Master Emerald, Knuckles is a bit anti-social and keeps to himself. He is short-tempered and easily fooled, but he makes up for it with his courage and fists. Often the butt of Sonic's jokes.
Adorkable: He tends to be shy and awkward around girls.
Butt Monkey: Prone to slapstick, and often the butt of gags from the rest of the team (often owed to his loner attitude). You know you're low on respect when even Cream The Rabbit mocks you. This is downplayed in the comics, though he's still kinda bumbling in tone.
Commander Contrarian: Unlike the others, who took enjoyment settling down and learning about Earth, Knuckles was vehement on returning to their home world as soon as possible, often arguing with the team's decisions or attempting his own strategies. Of course, it never went the way he wanted.
Friendship Denial: In a couple of episodes of the first season, he loathes the idea of being Sonic's friend. Justified in that the hedgehog's snarky attitude and reckless behavior seriously got in his nerves. Plus, he has better things to do as the guardian of the Master Emerald.
Sonic's self-proclaimed love interest, Amy is an optimistic, strong-willed girl who has a long-standing crush on Sonic and wants to be his girlfriend. While she means well, she can be a bit of a handle and often glomps Sonic. In battle, she uses her trust Piko Piko Hammer. Turns deadly with her Hair-Trigger Temper.
A six-year old rabbit, Cream is the Tagalong Kid of the protagonists. She is very sweet and good-natured, though she misses her mother Vanilla. Cream is accompanied by Cheese, a loyal Chao who usually mirrors her feelings.
Badass Adorable: Occasionally. The rest of the time she has to settle for just being adorable.
Berserk Button: Calling Cheese her pet - he's her friend. She also hated being questioned about her role with the team because of her age. Granted both are more "Mild Sulk Buttons" than a berserk rage, but for Cream, it's a pretty jarring showing of temper.
A jewel thief bat who begins neutrally aligned but ends up as a government agent working for the President of the United States. She forms a friendship with her partner Topaz, and has a complicated relationship with Knuckles.
A powerful, black hedgehog who is the final result of Project Shadow, a scientific experiment headed by Eggman's grandfather Professor Gerald Robotnik. He is released by Eggman to conquer the world, though Shadow has his own motivations. Becomes an Anti-Hero in the third season.
Super Strength: With his limiters off, he may be the strongest character in the show, with such feats as taking down an entire metarex fleet with one blow. Even with them on, he's capable of overpowering Sonic fairly easily.
Vocal Evolution: In their first appearance in Episode 39, Jimmy Zoppi voices Vector in a gravelly lisped tone. In their later appearances, his rendition is completely altered into an extremely nasally bellow.
Ambiguously Human: On top of having cartoonish proportions Eggman is also freakishly big compared to normal humans. He had to kneel down quite a bit to shake the president's hand, which also allowed the viewer to see that Eggman's fists are bigger than a normal human's head.
Anti-Villain: Essentially becomes one as the series goes on. Taken even further in the comic.
Beware the Silly Ones: Sometimes. In the earlier episodes at least he is feared by the humans, with a lot of his plans coming off as genuinely deadly until Sonic intervenes. He did also nearly kill Sonic at the end of the first season.
Stout Strength: Once beat up a bunch of crocodiles and broke a mechanical lazer turret with his bare fist. In an issue of the comic he actually wrestles Sonic in hand to hand combat, and holds his ground for a while.
Villain Protagonist: By the end of the comic's run, Eggman is practically the main character. Granted he held onto his "villain" role by a thread by that point. Has odd moments of this in the anime as well (he is at the very least more spotlighted than Sonic).
Worthy Opponent: Views Sonic as this (even if a lot of their bouts are somewhatone sided). His life becomes empty without Sonic around to spar with, and frequently teams up with him when another antagonist endangers them both.
Vocal Evolution: The two bots are voiced in a stiff Robo Speak in early episodes of the English dub. Throughout the first season, while their overall pitch and synthetics remain largely the same, they gradually fluctuate into emotional human-like acting similar to their Japanese voices.
Co Dragon: Briefly acts as one alongside Chaos to Eggman, following his brothers "demotion".
Gender Bender / She's a Man in Japan: For unknown reasons Gamma was referred to as female in the Dutch dub, in so far that Amy solely referred to Gamma as 'Miss Robot'. The gender change may have been based on Gamma's helium pitched voice in the English dub. It's incredibly bizarre for anyone who actually played Sonic Adventure.
Authority Equals Ass Kicking: This guy BEAT Super Sonic (likely very badly considering he only had some slight superficial damage while Sonic was exhausted), who was presented as invincible in the first two seasons.
Manipulative Bastard: We learn in "Shadow's Arrival / The Cosmo Conspiracy" that he secretly manipulated Cosmo into using Sonic and his friends to gather all of the Chaos Emeralds for him. In "The Lost Planet / Eye Spy" after that, it is revealed that Dark Oak had been using a device implanted within her head to make her his unwilling spy the whole time.
Orcus on His Throne: He sends Metarex out to kill Sonic, and besides that mostly just sits around and does nothing. Especially jarring given that it turns that he could have easily found and killed him whenever he wanted to.
Taking You with Me: After Super Sonic and Super Shadow destroy the shell of the Final Nova's planet form, he decides to try his hand at attempting to OBLITERATE the ENTIRE universe with himself in his final moments.
Dark Oak: Foolish hedgehogs. With the help of the Planet Egg, you were able to stop my plans to transform the universe. But you can never win this battle... If the Metarex cannot rule the galaxy, then we will destroy it! Muahahahahahah...!
We Can Rule Together: He uses this with Sonic in the fourth-to-last episode before devouring him for deciding he would rather they get rid of him than him join the Metarex and let them take over the galaxy without a fight.