Aelita's hair is pink on Lyoko and in the real world as well. Aelita wears two main outfits throughout the series. Her daytime outfit in the first season is a maroon skirt, yellow shirt and pink jacket. She wears a dark pink jumper dress over a light pink hooded long sleeved shirt and dark pink knee boots for the second and third season. In the fourth season, her outfit consists of a dark purple dress that comes to her knees and light pink Quarter lenth leggings underneath. Her boots are a deep red. Her night clothes consist of white socks and an over sized pink t-shirt with a red letter A on the front.
She wears two different outfits depending on the season. For the first three seasons, Aelita's outfit consists of a pink mini skirt and a matching top that go over trousers and a long shirt that are both off-white, and matching shoes. She also has elf-like ears, with a small dangle earring in the left one. Her eyes are green. In the fourth season, Aelita receives a new pink form-fitting suit on Lyoko, which has a pair of retractable energy wings that enable Aelita to fly.
Her main interest is music, specifically audio mixing. Her childhood memories show that Franz Hopper taught her to play the piano at an early age. In the fourth season, she wins a contest to star in one of the Subdigitals' concerts. She, like Jeremy, is also a capable programmer and an excellent student.
Aelita's main power on Lyoko is her creativity, which allows her to alter small portions of Lyoko's terrain at will. She can use the same power to create clones of herself, though they have limited functionality, acting in a pre-determined manner. Aelita also has the power to deactivate the towers on Lyoko, the main component in stopping Xana's attacks in the real world. In the third season, Aelita is able to defend herself by generating pink orbs (called "Energy Fields") which can destroy any monster on contact, regardless of where they hit. Two energy fields can also be touched together, forming something like a chain that can stop certain attacks (such as a Megatank's shot).
Jeremie has blond hair. On Earth in the first three seasons, he wears a blue turtleneck, brown pants and blue-gray shoes. He also has glasses, because he is nearsighted. In Season 4, his outfit is a dark red long-sleeve shirt, brown pants with light blue stripes going down the side of the legs, and dark blue shoes. His pajamas are dark blue.
Something of a workaholic, Jeremie invests the majority of his time into finding ways of stopping Xana, having spent the entirety of season one trying to materialize Aelita onto the real world, and spent all of season two trying to make an anti-virus after Xana infected her. In season three, he spends most of his time trying to find a way to virtualize the group into the Internet directly, until Xana possessed the newly-inducted William and destroyed Lyoko. At the end of the season, Jeremie receives a message from Franz Hopper, and manages to recreate Lyoko using the codes. In season 4, he spends the majority of his time locating Replikas, deciphering data from the internet, and trying to free William from Xana. From Season 2 onwards, one of his major overall goals is to free Aelita's father, Franz.
Often, his determination to fight against Xana will take priority and he will leave his friends in the interests of working more. They rarely respond positively to this; however, he usually finds a way to make things up by the end of the episode.
Jeremie was the one who discovered Lyoko, as well as Aelita, and over the first season he became very attracted to her. He is very attracted to Aelita's intellect, curiosity, and bravery, and although Jeremy can be shy at times, he has sought a romantic relationship with her, and it has been seen that Aelita feels the same way in many episodes.
Odd has long hair spiked to a peak, but not bristling with its eternal wick violet. The first of Odd's two outfits in the series consists of a long-sleeve shirt and bellbottom pants, and platform shoes. His hair is styled into a large point in the same fashion as his hair on Lyoko. He also has a purple diamond on the front of his hair (which is naturally that color, as seen in both "Unchartered Territory" and "Revelation"). In the fourth season, his outfit consists of a purple hooded sweatshirt with a lighter purple shirt underneath, purple bell bottoms, and dark red-orange shoes. His night clothes are red and yellow, not purple, and probably due to the fact he did not buy them.
Odd considers himself to be something of a ladies' man, having managed to date almost every (similarly aged) girl at the school in the two years he's been attending it, sometimes two at a time. A recurring theme in the series is Odd attempting to impress one girl or another, if he is not already dating them. However he has shown more of a close attachment to a girl named Sam that doesn't attend his school, but these feelings might have changed as she withheld information from Ulrich about a Xana attack.
Another recurring theme, though less prevalent, are jokes about Odd's size in comparison to his eating habits. Despite eating two or three portions at every meal, Odd never gains weight or height, being the shortest member of the group, which is somewhat disguised by his platform shoes and hairstyle. The school nurse attributes this to Odd's high metabolism.
Odd has a pet dog named Kiwi, which he keeps in his room against school policy. Despite the rule against dogs, most of the students know about it. Odd also shares a room with Ulrich. The others have their own rooms or live at home. This occasionally results in arguments between the two on roommate-related issues. In "Distant Memory", it is revealed that Odd has five sisters.
On Lyoko, he is dressed as a self-described "giant purple cat." The outfit is almost identical to the one he wears in the real world color-wise, but has no sleeves and is generally closer-fitting. To complete the "giant cat" motif, Odd only has four fingers (three digits and a thumb), complete with claws, and a tail. His forehead and cheeks also have purple markings on them. In the fourth season, he receives a new outfit almost identical to the previous one, except being a slimmer full-body suit, with slightly altered highlights, and with cat ears in addition to his human ones. His vehicle is the Overboard, a similarly-themed purple hoverboard.
Odd's gloves are equipped with arrow launchers, which are his main weapon. Odd prefers to attack from long-range, using his accuracy to destroy monsters out of harm's way, but will often fight close-quarters in order to get a shot in. In the first season, he can only fire 10 arrows in one setting, but eventually gains the ability to fire as many as 10,000 with a reloading program created by Jeremie. Odd's powers vary between seasons. In the first season, Odd has the ability to see into the future, though not at will and only for short periods. The ability (as explained in the third season episode "Triple Trouble") was lost in the second season when Jeremie improved their abilities. In exchange, Odd gets an arm-mounted energy shield which appears when he summons it. His claws also allow him to climb up objects with ease. In the third season episode "Triple Trouble", Odd temporarily gained the power to teleport, but the program bugged up, causing him to triplicate, thus discouraging him from keeping the power.
Yumi's hair is half-long black, headed back and sides. In the first three seasons, she wears a black turtleneck and black ankle pants. Her hair is usually left hanging down. In the fourth season, her outfit is slightly lighter but still mainly black, consisting of a long-sleeved shirt with an extra large neck hole. Her pants cut off halfway between her ankles and knees. Both of her outfits reveal her stomach.
In terms of character development, the two major themes revolving around Yumi are her relationship with Ulrich Stern and her parents' unstable marriage, the former of which is the central focus. Yumi's relationship with Ulrich remains platonic, though they almost kiss in "Routine" and decide to keep it a secret. Yumi decides to outwardly declare their relationship to be just friendship at the start of the third season, though the episode "Cold Sweat" and the series finale "Echoes" implies the two eventually explore their romantic relationship again.
The second season introduces Yumi's younger brother, Hiroki. He constantly teases Yumi about Ulrich. Most of the time, Yumi acts as if she can't stand Hiroki, but episodes such as "Lost at Sea" show that Yumi does care for him.
Yumi's outfit is modeled after those worn by geisha. Her outfit consists of a short-sleeved/hemmed kimono over red tights, black thigh-length boots, red eye liner, red blush on her cheeks, a white-painted face and neck, and some red on her lips to complete the look. She also has a yellow sash tied to her back. Her hair is bunched up into a small bun with three bangs left hanging. In the fourth season, Yumi gets a new, ninja-like outfit. It consists of form-fitting, pink and purple body suit with flowered shoulder pads, but retains the yellow sash from the previous one. Her hair is worn down instead of in a bun. The geisha makeup is less prevalent with the new outfit, though it's more apparent with her 2D model. However, she has two strange pill shaped objects above her eyebrows. Yumi uses the Overwing, a hovering scooter, for travel on Lyoko. She usually shares this vehicle with Aelita.
Yumi's main weapons on Lyoko are her dual metal fans that function like boomerangs when thrown. In flight, they turn into fast-moving, saw-like discuses which cut through almost anything, and also serve as shields to block enemy laser fire. Her fans now appear and disappear at her will (as long as they are in her hands) rather than concealed behind the yellow bow on her back. She also has telekinetic powers.
Ulrich has brown hair. In the first three seasons, he wears a jersey with a vest over it and cargo pants, all varying shades of green, and white shoes. In the fourth season, his vest is replaced by a jacket. His night clothes are boxers with a white vest.
Ulrich doesn't say much about his personal life and is evasive when someone asks him about himself or his family. His parents, his father in particular, are very hard to please and have high expectations of their son. He also has trouble expressing his feelings, mainly where Yumi Ishiyama is concerned. A common theme in the series is Ulrich only admitting to something after a brush with death or an otherwise dire scenario. In addition to his troubles with Yumi, Ulrich has to deal with Sissi's affections. Due to her being the daughter of the principal, he is often forced into humoring her in order to get something from her father.
Ulrich's Lyoko attire is modeled after a samurai, minus armor, and he carries a sword. An Oni is drawn on his back and the clothing is largely colored yellow and black. He gets a new outfit in the fourth season, which trades his more loose-fitting clothes for a tighter yellow and brown body suit (similar to William's). A device on his back is traded for his sword sheath, which, in addition to carrying two swords, hides the blades when they're not in use. For travel, he uses a one-wheeled motorcycle called the Overbike, which is also capable of flight.
Ulrich's two swords allow him to cut through monsters with ease or deflect enemy laser fire. His super-sprint speed on Lyoko is enhanced, such that he can deflect even rapid laser fire with relative ease and run faster than most monsters. He can create two clones of himself to aid in battle (called Triplicate), each of which can take one hit before being destroyed. He can bring these clones back together into him (called Fusion). He can also summon his clones to make a triangle around his enemy, then attack it when least expected. Both he and Yumi are practitioners of Pencak Silat, and in several episodes take classes with Jim.
Ulrich usually makes absurdly crude jokes such as in episode 47: "Last time I checked, the atmosphere was electric."
William has very short, dark and unnatural black hair. William's first outfit consists of a short-sleeved black shirt with a long-sleeved red undershirt, blue jeans and boots. His outfit in the fourth season consists of dark-blue pants, a black shirt with a red logo, and a tan jacket to replace the red undershirt.
William joins the Lyoko warriors near the end of the third season, but is quickly possessed by Xana. Xana then uses William to destroy Lyoko. From this point until his final freedom, William is helplessly kept under Xana's control, unable to help the other Lyoko warriors. Xana uses William to command his monsters in battles to even the odds. He even uses a unique Manta, which is colored black instead of the standard blue, as a vehicle for William on Lyoko. He is freed from Xana in "Down to Earth", but the group is wary to trust him again. Xana again possesses him in "Fight to the Finish", and he is once again freed once Xana is destroyed.
In his short appearance in "Final Round", William's Lyoko attire consists of a white and blue form-fitting bodysuit with a red belt. After he is taken over by Xana, his outfit changes to a similar, all-black outfit with red outlines and the eye of Xana on his forehead and chest, as opposed to his eyes. He also gains a spiked gauntlet on his left arm capable of blocking attacks.
William's primary weapon on Lyoko is a large white sword. His Xana-themed version has black vines creeping up the blade and the eye of Xana near the hilt on either side. Like Ulrich's sword, it can absorb and deflect lasers as well as attacks from the Lyoko warriors. Under Xana's control, William's strikes have such force that the sword damages the terrain. Disc-shaped blasts of energy can also be fired from the sword, another Xana-given ability, by charging and swinging it.
Xana's primary power through William is smoke manipulation, reflecting Xana's use of smoke-like ghosts in the real world. Xana forms the weapon from smoke and reduces it to such when not in use, which allows him to call the weapon back to William if they are separated. He can also reduce William to smoke, allowing him to move at high speeds, and can quickly transform him back upon reaching his destination. Finally, he can create smoke in William's hands and fire it at his opponents to restrain them, after which he can use the smoke to achieve a limited form of telekinesis on his target. Other powers include hovering and long-range vision.
While possessed, William doesn't devirtualize when dealt enough damage. Instead, he is reduced to glowing red smoke which dissipates into the ground. Additionally, while Xana usually needs only one successful hit through William to devirtualize the Lyoko warriors, it takes either several hits or one fairly powerful attack (being cut in half, for example) for him to do the same.
In all seasons, Xana is an eye made up of a roundabout in the centre surrounded by two circles. Four tabs occupy the contour of the outermost circle: a longer than others at the top and three other shorter bottom equidistance from each other. The center is a bit wider. In "Fight to the Finish", Xana is destroyed by Jeremie's multi-agent program.
Xana's main power is possession through an energy-based, ethereal "ghost", capable of possessing virtually any object and likewise modifying it to almost any necessary end. When a human is "Xanafied"("Xanatifié" in french) or possessed by Xana, their eyes often have the Eye of Xana symbol (found on all of Xana's monsters) instead of pupils. The ghosts themselves can also manifest themselves as people without the need for a host. Among the common abilities imparted by the ghosts are electricity-manipulation, phasing through solid matter, enhanced strength and speed, and the less common ability to self-replicate.
In the first three seasons, Sissi wears a yellow banner on the front which holds its hairpieces. She is dressed in a pink t-sleeved shirt with a heart bouffantes yellow top and a dark pink mini skirt over red trousers with pink shoes.
Franz has gray hair, beard and moustache. He wears sunglasses. Franz wears a white blouse in all seasons.
Franz is variously depicted in Lyoko with sphere-shaped constructs. In "Aelita", he is depicted as numerous white spheres, while his appearance in "Distant Memory" is that of a larger purple sphere. Franz Hopper, like Xana, can reach out to the real world through the use of the towers, but not nearly as effectively as Xana can. He helps the warriors at various points in the series, even helping them to recreate Lyoko after its destruction in "Final Round". In "Wrong Exposure", his name is revealed to be Waldo Schaeffer (the name printed on the folder in the closing credits), while "Franz" is actually his middle name and "Hopper" is his wife's, Antea Hopper, maiden name. In "Fight to the Finish", he sacrifices himself to give the multi-agent system enough power to completely wipe out Xana. The act creates a sense of irony, considering that the majority of the series was spent trying to rematerialize him.
Jim's hair is quite short, chestnut and prepared by its banner. In the first three seasons, Jim wears a white vest, concealed under a dark red tracksuit which covers all his upper body and its bedaine, and a dark grey jogging pants and sneakers.
Milly has red hair, separated at the rear in two duvets. In Seasons 1-3, she wears a small pink jacket and a dark red skirt. She also wears black tights and little black boots. In Season 4, she wears a light blue t-shirt with a red scarf and dark pink shorts.
Tamiya has black hair tied back in cornrows. Tamiya wears a T-shirt with khaki pants and a small necklace in the first three seasons, and in the fourth season, she wears a pink jacker and olive green khaki pants. Her hair is also in pigtails, similar to Milly. She is also one of the few Black characters seen in the series.