Real Name: Kirigaya Kazuto

Kirito is the protagonist of the series. He is a "solo" player as well as a beater (stands for beta tester and chea-ter), a player who hasn't joined a guild and usually works alone. Kirito is also one of the clearers in SAO. When it is announced that the players of Sword Art Online can no longer logout, he is surprised like everyone else, but unlike everyone else he quickly gets over it and accepts it, to an extent. He mainly uses a one-handed sword "Elucidator" and usually wears all black in-game, as it adds to stealth, and gives him his nickname "The Black Swordsman". In SAO, he is the possessor of «Dual Blades», a unique skill which he only uses in emergencies to avoid attention for being one out of the two people to have unique skills.
His game alias is Kirito, which is created by taking the syllables of the first and last Kanji of his real last and first names respectively: (Kirigaya Kazuto). In the real world, he lives with his mother and younger cousin/sister in a family of 3. He was adopted by Kirigaya Minetaka and Midori (Suguha's parents). His mother (who is actually Midori's sister) and father passed away after an accident when he was about 1 year old. When he was 10 years old, he found out the truth. He treats playing in a VRMMO the same as living in the real world (a result of living in SAO for two years).

Real Name: Yuuki Asuna

Asuna is the main female protagonist of the series. She is a friend of Kirito and is a sub-leader of the guild Knights of the Blood Oath, a medium-sized guild of about thirty players, also called the strongest guild in Aincrad. Being one of the few girls that play SAO, and even more so that she's extremely pretty, she receives many invitations and proposals. She is a skilled player earning the Title "Flash" for her extraordinary sword skill. The KoB has assigned her two bodyguards, one of whom despises Kirito.
Her game alias is the same as her Real World name. Later, she falls in love with Kirito and they marry in-game. In real life, she lived a very stressful life, forced to live up to the high expectations of her parents. She felt that she would live her life following her parents rule, and never once went against that idea. But after living in SAO and meeting Kirito, she gain more emotions and realized what it was like to actually live, and looks back on her past with disgust. She has a very strong will, able to sacrifice days of sleep to level up. She deeply loves Kirito and once explained he was her reason of going on in the game, she could not survive without him. He saved her by showing her people could live well in SAO, he saved her from her nightmare. She also told Kirito she would commit suicide if he were to die during the 75th boss raid, after he asked her to stay away from the fight. She intended to do so and she became desperate when Kirito asked Heathcliff to prevent her from comitting suicide if he died during their duel. She sacrificed herself to save him; however, she was reunited with him shortly after he "died" defeating Heathcliff in a place Kabaya created for all three to talk.

Initially a side story character in SAO, later becomes an accompanying/support character in ALO. At first thought to be a lost child in SAO, she is actually an artificial intelligence program. Her full designation is «Mental Health - Counselling Program», MHCP version 1, codename, «Yui». She was designed to monitor the emotions of players and appear at their sides to hear and help them out. However, since the moment everyone was imprisoned in Sword Art Online, she was forbidden to come in contact with the players and complete her prime directive. Unable to do anything but suffer as she monitored the emotions of the trapped players, she came upon Kirito and Asuna whose emotions were those of joy and peace in the sea of fear, despair and rage. She sought them out, appearing to them as an amnesiac child whom they adopted. In the end she was nearly deleted by Cardinal, the management system of SAO. But Kirito saved her by converting and storing her data into his own Nerve Gear. Later shows up in ALO as a Private Navigation Pixie and helps Kirito along with Lyfa to find Asuna. Refers to Kirito as "Papa" and Asuna as "Mama". And gets very annoyed if any girl other than Lyfa or Asuna gets close to Kirito. Kirito uses his skills and resources in the real world to make a device for Yui to view the real world even whilst she is in virtual reality and gives her the ability to communicate with them.

Real Name: Kirigaya Suguha

Kirigaya Suguha is raised with Kazuto as his sister since her parent took Kazuto in after his parents died in a traffic accident. Kazuto is Suguha's first cousin; his mother was Suguha's mother's sister. They were taught Kendo by their grandfather, who was a former policeman and a Kendo champion. Kazuto gave up after two years and embraced the world of technology, leaving her behind. The truth is, Kazuto found out he was not her real brother around this time and their distance became further and further apart, until they were practically strangers before the SAO Incident. She continued with Kendo and became a national quarter-finalist.

In the game ALO, Suguha appears as a more grown up person than a child. She has bright green eyes and wears white and green clothes. She also has a white and green collar on her neck. She has long blond hair, often tied up with a flower like hairband. Her hair bangs, however, is not tied up with her hair. Like all of the other players in ALO, her ears are quite long and pointy.

Real Name: N/A

A side story character in SAO. She was a member of "Black Cats of the Full Moon" which was the first guild Kirito joined. Kirito was especially attached to her. However she died along with the majority of her guild members which led to Kirito wallowing in despair and self-loathing until he read the time delayed message she left for Kirito. Even after the message gave him the strength to live, he never joined another guild until the events of Volume 1.

Real Name: Ayano Keiko

A side story character in SAO. One of the rare beast tamers in the game. She, very early in the game was able to tame a dragon which gave her immense fame, but she was just a mid-level player. Due to her fame and being a girl, many tried to get on her good side, causing her to get a bit of an inflated head. She usually stay away from the males, who tried to marry her despite the fact that she was only 13. After getting lost in a forest, she lost her beast and only friend in the game. Kirito rescued her, and helped her as she resembled his sister. She gained feelings for him, but once she realized his skills, she realized that they could never be together in the game. Later on it is revealed that Pina (her beast) was revived. She joins Kirito and his friends in ALO right after they meet in the real world; they often go together in quests. Pina is later revealed to be the undead dragon steed of Healthcliff, and one half of the final boss.

Real Name: Shinozaki Rika

A side story character in SAO. Her profession is a blacksmith. She is a close friend of Asuna who recommended her to Kirito. Kirito commissioned her to forge a second sword for him, as good as his first sword «Elucidator». Then he accompanied her in the quest for the special ore required for the job. During the quest, she also develops feelings for Kirito. She is devastated when she finds out that Kirito is Asuna's crush. But finds solace when Kirito tells her about the "Black Cats" and that for the first time after losing his guild he had felt natural while partying with her. In the end when the game clear message appears she instinctively knows that it was Kirito who did it and declares her love for him. Proposes a one-month truce with Scilica after Asuna wakes up but is shown regretting it. She becomes a regular player in ALO and frequently takes on quests with Kirito and his friends and takes up tasks of upgrading their equipment.

Real Name: N/A

Argo is a «Sword Art Online» beta tester who sells information between players. Kirito often looks to her for her skills. Argo is first introduced as the beta tester who serves a middleman between Kirito and a prospect buyer of his «Anneal Blade +6». She was later revealed to have assisted players by creating a guide book for players. Inside are hunting locations and other resourceful information pertaining to staying alive in the game.
She is willing to sell any information except names of SAO beta testers. She also serves as a middle-man of player dealings.

Argo's whiskers were originally a mark written on her face when she tried to complete the quest that awards the "Martial Arts" extra skill. Unable to complete the quest, the mark remained on her face throughout the entire «SAO Closed Beta». She reapplies a similar makeup on the official server service.

Real Name: Tsuboi Ryotarou

A friendly player that meets Kirito at the start of the game and quickly befriends and learns from him. He and Kirito later separate because he has friends who were also new to the game, and since he was taught by Kirito who was an experienced player, he couldn't leave them. He uses a katana to fight and leads a party. Klein reunited with Kirito after two years when they run from a monster and start having lunch.

Real Name: Andrew Gilbert Mills

An axe wielder who owns a shop in SAO. He is 180 cm tall with muscular body and set his hairstyle to be bald. Despite his scary figure, he is kind hearted and allocated most of his earnings to help players in middle floors. Kirito is a regular in his shop and they seem to have a good relationship. He runs a shop named «Dicey Cafe» in the other side, which had been kept from closing for two years of his absence by his wife. That shop then becomes Kazuto and company's meeting place in the real world.

Real Name: Kayaba Akihiko

He is the owner of the «Unique Skill» «Holy Sword» and is considered to be strongest player in-game[1]. He wields the one-handed sword and a tower shield collectively called as Liberator. He also was able to hold off the boss of the fiftieth level for ten minutes by himself, which earned him the title «Man of Legend». It is also rumored in SAO that Heathcliff's health has never gone into the yellow zone.

Real Name: N/A

Kuradeel was one of the 10,000 players who got trapped in the cursed death game, «Sword Art Online». He was originally assigned by his guild, «Knights of the Blood», to protect Asuna. He was later revealed to be a member of the famous PK guild, «Laughing Coffin». He dueled with Kirito and lost. He later tried to kill Kirito by setting a trap and killing two of the guild members. Luckily, through the meddling of Asuna, Kirito was able to finish Kuradeel. He was originally portrayed as devoted guild member before being revealed as a member of the «Laughing Coffin».

Real Name: N/A

Godfrey was one of the 10,000 players who got trapped in the death game «Sword Art Online». He was was a easy going chracter. He was part of the guild «Knights of the Blood». He was killed by Kuradeel, during his revenge against Kirito.

Real Name: N/A

Kibaou is one of the players who were part of the boss raid of the first floor. He blames the beta testers for the deaths of the beginner players, and demands that all the beta-testers apologize for the deaths that they "caused", give all the items they got to other players, and give out all their experience points. He also blames Kirito for the death of Diabel.

Real Name: N/A

Diabel was one of the 10,000 players of «Sword Art Online». He appears in the «Aria in the Starless Night» side story. Diabel called himself a knight(even though there is no class in SAO) he had a bronze armor on chest, shoulders, arms and shins, with a large longsword on his left waist, and a kite shield on his back.

Real Name: N/A

Thinker is one of the 10,000 players of the cursed death game «Sword Art Online». He is in charge of the popular net gaming information site «MMO Today» and also formed SAO's largest guild «The Army».

Real Name: N/A

Yulier is a silver haired whip user who is part of the Aincrad Liberation Force. She is devoted to aiding Thinker with his duties. After escaping from «Sword Art Online», Thinker marries her.

Real Name: N/A

Covatz is a lieutenant in the Aincrad Liberation Force He has a gung ho attitude, driving his men to their limits, and forcing them to continue fighting a battle that can not be win easliy by keep fight without rest. He was killed by The Gleam Eyes after his party entered the room without any major preparations.

Real Name: N/A

Keita was the leader of the «Black Cats of the Full Moon», a small guild in «Sword Art Online» before committing suicide after finding out that his guild got wiped out. He wielded two-handed staves, and put the welfare of his guild first and blamed Kirito for the deaths of his guild members. He is mentioned in many of Kirito's retellings of the demise of Keita's guild[1][2]. He could be described as a hopeful and forward type person, and his dreams are to be on the frontlines of SAO helping to clear the game.

Real Name: Tetsuo

Ducker was the member of the «Black Cats of the Full Moon», a small guild in «Sword Art Online». He was killed along with most of his guild when a trap was triggered that called multiple monsters and prevented the use of crystals.

Real Name: N/A

Yoruko is one of the 10,000 players trapped in the online game «Sword Art Online». She was a former member of the guild «Golden Apple». She and Caynz team up to find the culprit who killed Griselda. She was part of a small guild called Golden Apple, which only had eight members and among them was her boyfriend, Caynz. One day, the group found a rare-drop item and they voted to decide what to do with it, Caynz was in favor of keeping the item, so she also voted in favor of keeping it, but after losing in the voting three to five, they decided to sell the ring. The guild leader, Griselda departed up the front lines to sell the ring but never came back, only to discover that she was dead. The guild was disbanded but the culprit was never found. While Kirito and Asuna are having dinner, she screams from seing Cains hanging from the chruch's window, later she explains that she was going to eat with Caynz but the got separated. She stays in an Inn while Kirito and Asuna investigat, she later talks to Schmitt, and gets exaltated before being stabbed in the back by the mysterious murderer that also killed Cains.

Real Name: N/A

Schmitt is a former member of Golden Apple and a current officer of Divine Dragon Alliance. He was a suspect on the Griselda murder incident.

Real Name: N/A

Cains is one of the 10,000 players trapped in the online game Sword Art Online. He's a former member of the guild Golden Apple and teamed up with Yolko to find out who killed Griselda. He was part of a small guild called Golden Apple, which only had eight members. One day they found a rare-drop item and they voted to decide what to do with it, Caynz was in favor of keeping the item, but loosing in the voting three to five, they decided to sell the ring, but when the leader of the guild depparted, she never came back, and they found out that she was dead. When Kirito and Asuna were going to have dinner, Yolko screamed and Caynz was found hanging outside the church with a weapon piercing through him. Kirito and Asuna try to save him, but he dies before they reach him.
The next day it was revealed that he wasn't dead that, along with Yolko, they faked their deaths to trick Schmitt and found who killed their former leader Griselda. After they record Schmitt's confession of being an acomplice they're surrounded by the top three of the Laughing Coffin guild, but are saved by Kirito, it's later revealed that Grimlock was who planned Griselda's death and wanted to kill them to finally cover the incident.

Real Name: N/A

Grimlock is a player in Sword Art Online and a former member of the guild Golden Apple. He was the murderer of his in-game and real-life wife, Griselda. He killed her because he didn't like her change in personality as a result of the beginning of the SAO. He also aided Caynz and Yolko in their plans to catch the Griselda's killer by forging them weapons to use in the in-AREA murders.

Real Name: N/A

Griselda was the former leader of the «Sword Art Online» guild Golden Apple before it's dissolution. Her strong personality capable of leading a guild developed after the start of the death game. Described as the perfect wife (cute and obedient) by her real life and in-game husband Grimlock, real-name Yuuko took to SAO much better than her partner. At the birth of the game she began to develop an active and lively personality distinct from her moderate real counterpart. This change worried the emotionally unstable Grimlock, provoking him to plan and carry out her murder at the hands of the killing guild Laughing Coffin.
She was killed when she was appraising a +20 agility rare ring drop on the frontlines.

Pina is Silica's blue «Feathery Dragon» with its body covered in soft, pale blue feathers and two feathers instead of a tail. It is the first monster to be tamed in Sword Art Online. It understands Silica's commands and will protect her in any way it can, as it is her «Familiar». It is also present in ALO as her Cait Sith familiar.

Real Name: N/A

Rosalia is the leader of the orange guild «Titan's Hand», she was caught by Kirito and sent to the prison managed by «The Army».
As the leader of the guild, and in order to maintain her "green" status, she looks for victims and lures the players to a place where the other members of the guild attack and loot the player, while she mantains her «green cursor» to avoid suspicion.

Real Name: N/A

She's one of the 10,000 players trapped in the death game Sword Art Online
Sasha is a woman who takes care of the younger players of SAO in Starting City. After being freed from SAO she eventually joins ALO.

Real Name: N/A

Nishida is one of the oldest players in Sword Art Online. In the game, he is a fisherman, but in reality, he works at Tohto Broadband Connection, which is a network operator company that runs the game. He was in charge maintaining the network connection before being trapped in the game. Kirito, on a failed attempt to fish at a lake, meets Nishida on the twenty-second floor of Aincrad. The swordsman invites the elder to his and his new wife's home, where Nishida meets Asuna. At the couple's house, he mentions that the lake Kirito was fishing in had the local god, which takes a form of a fish. Kirito says he would like to take up the challenge, so soon, Nishida and Kirito goes to he lake while Asuna waits on the shore. Nishida first gives the bait to the fish, then Kirito switches out to use his strenghth to pull the god out pf the water. A mishap leads Asuna to fight against the god, and she kills it, but not efore revealing her identity as the sub-leader of the «Knights of the Blood». Kirito recieves a fishing rod monster drop from killing the monster, which he gives to Nishida as a gift.

Real Name: Shinichi Nagata

Recon is Lyfa's friend and mentor in ALfheim Online. He is skilled in concealment and high level dark magic. His real life name is Nagata Shinichi.

He harbors a crush on Suguha, being her classmate in real life. He is key in investigating the Salamander's infiltration of the Sylph, and uncovering Sigurd's plot. He later rejoins Kirito and Lyfa at Aarun, and urges Lyfa to leave and return to Sylvain, after he finds her upset. Later he confesses to her and ends up getting punched. After Lyfa returns from meeting Kirito again, she informs them they are attacking the World Tree.
During the World Tree assault, Recon breaks off and attracts multiple guardians, and later uses high level dark magic called Sacrifice to self-destruct, which entails a higher death penalty. This action buys enough time for Sylph and Cait Sith reinforcements to arrive.

Real Name: Sugou Nobuyuki

As the Fairy King Oberon, he keeps Asuna locked up in a bird cage at the top of the World Tree. In the real world, he confronts the powerless Kazuto by voicing his intentions of wedding the unconscious Asuna. While keeping Asuna locked up in ALO, he constantly visited her just to fool around with her. From his actions, one could say that he is a pervert. After Kirito manages to ascend the World Tree, Oberon and Kirito have a devastating fight. By using his system commands, Oberon is able to completely dominate Kirito. Fortunately, Kayaba Akihiko saves Kirito by overriding Oberon's authority. Then, in the real world, Sugou attempts to kill Kirito when he is running to Asuna's hospital. This backfired and ended up with him going to prison.

Originally selected by Asuna's father to marry Asuna, he was adopted into her family on her father's wishes. He attended the same school with Kayaba Akihiko, who he viewed as a rival. During the «Sword Art Online» incident, he took advantage of the chaos to steal test subjects for research along with Asuna. In «ALfheim Online» he adopts the persona Fairy King Oberon.