The Accel World light novel, manga and anime series features a large cast of characters created by Reki Kawahara and illustrated by HIMA. Set in Tokyo in 2046 when devices known as Neuro-Linkers have enabled fully integrated augmented reality, the main character Haruyuki Arita is offered a virtual reality massive multiplayer online (VRMMO) fighting game called Brain Burst by Kuroyukihime, the student council vice-president at his school. Together with Kuroyukihime and his other friends, Haruyuki fights as a Burst Linker to ultimately attain level 10, the highest attainable level, and meet the creator of Brain Burst to learn its true purpose.

The main characters are members of Nega Nebulas, also known as the Black Legion.

Haruyuki Arita (有田 春雪, Arita Haruyuki) is the main protagonist of Accel World. Commonly referred to as Haru by his close friends, he is a short and overweight boy with low self-confidence until he meets Kuroyukihime. Although he is generally smart and careful when it comes to everyday life, Haru tends to get reckless while protecting Kuroyukihime. He views her as a mentor, friend, and lover simultaneously, which has given him the utmost respect and loyalty toward her and her army. His non-accelerated avatar is a small pig that was originally forced on him by one of the delinquents, only keeping it because Kuroyukihime finds it "cute." While in Akihabara, Blood Leopard gives him a different avatar to fit in, taking the form of a small pink lizard.

Haru's Brain Burst avatar, Silver Crow (シルバー・クロウ, Shirubā Kurou), has a tall, thin, fragile metallic frame that is completely devoid of weapons, forcing Haru to fight barehanded. His avatar was created by his desires to be thinner and fly away into the sky in order to escape his miserable life. The avatar possesses a mouth underneath its visor, allowing Silver Crow to eat while in the game world. Silver Crow is the first and only avatar with the ability to fly, sprouting wings on its back when its special ability is activated. Lacking in both physical strength and defensive capability, Silver Crow is dependent on Haru's squash-honed speed and reflexes in order to survive fights. Silver Crow's default finishing move is a basic headbutt, typically ineffective in most circumstances. Haru eventually learns how to utilize the Incarnate System (IS) to focus his willpower, gaining the ability to form energy blades from the bracers on Silver Crow's forearms, a technique he names "Laser Sword", and later refines into more powerful and far-reaching versions called "Laser Lance" and "Laser Javelin". He also gains eventually another Incarnate Skill called "Light Speed" that sharply increases the speed of his flight for a short time.

For a period of time, Silver Crow has the Disaster Armor Enhanced Armament and becomes the 6th Chrome Disaster. In this form, he can predict the attacks of his opponents and use all the abilities of previous Chrome Disasters. In one battle, he can partially summon the uncorrupted form of The Destiny, which is one of the Seven Arcs used to form the Chrome Disaster Armament that was created by Chrome Falcon. Haruyuki is voiced by Yuki Kaji in Japanese and Erik Scott Kimerer in English.

Kuroyukihime (黒雪姫; lit. Black Snow Princess) is the leader of the Nega Nebulas legion. Her real name is Sayuki Kuroba (黒羽 早雪, Kuroba Sayuki) (although Sky Raker calls her "Sacchan"). Her pseudonym is Japanese word play with Snow White Shirayukihime (白雪姫; lit. White Snow Princess). Beautiful and popular, she is also the Student Council Vice-President at Umesato Junior High School. She has been a Burst Linker since she was eight years old. Kuroyukihime was formerly the Black King, although she was driven into hiding after beheading the first Red King, Red Rider, while trying to defeat the other kings to reach level 10. She values Haru as more than a subordinate and is often the voice of reason to him when he is willing to go to extremes to protect her. Prior to her hospitalization, she confesses to Haru that she fell in love with him. Her non-accelerated avatar is her real-world self dressed in black and sporting red and black butterfly wings. She is estranged from her family since she injured her sister, who is also the White King, out of anger after learning that she was tricked by her.

Her Brain Burst avatar is Black Lotus (ブラック・ロータス, Burakku Rōtasu), also known as "World End," a slender robot with a feminine form which features limbs ending in sharp blades. These weapons instantly cut anything they touch due to the Absolute Cutting Property the avatar possesses, which has the side effect of permanently removing whatever is cut from an opponent's avatar. However, the blades have a frail lateral portion that breaks after receiving too much damage. To compensate for this weakness, Kuroyukihime developed a technique she calls "Soft Act". Black Lotus has three special abilities: Death by Barraging; Death by Embracing, which was used on Red Rider; and Death by Piercing, a one-hit-kill direct attack. She also has three incarnate system skills: "Vorpal Strike", "Star Burst Stream" and "The Eclipse", that she learned from her former subordinate Graphite Edge. Lotus also displays an ability called Overdrive: Mode Green, which causes the purple parts of its body to turn green and increase its speed and attack power for a limited time. Lacking feet, Black Lotus hovers slightly off the ground via air jets on the legs, with which it is able to achieve incredible speeds. Kuroyukihime is voiced by Sachika Misawa in Japanese and Kira Buckland in English.

Takumu Mayuzumi (黛 拓武, Mayuzumi Takumu) is Haru's childhood friend and Chiyuri's boyfriend at the start of the series, nicknamed "Taku." Being smart and athletic, he attends a prestigious school. His non-accelerated avatar is the tin man. Initially, he abuses the enhanced reflexes he obtains while accelerated to have an advantage in the kendo tournaments he attends in real life. After Kuroyukihime is hospitalized, Takumu attempts to assassinate her until he is stopped by Haru, who convinces him to join forces. After confessing to Chiyu about what he's done, it seems they've broken up. Despite that he is waiting to see if Chiyu would get back together with him. He is a mentor figure to Haru due to his advanced knowledge of the Accelerated World. After teaming up with the Nega Nebulas, he transfers to Umesato Junior High School and begins wearing glasses despite the Neuro-Linker's ability to correct vision problems, wanting to see the world through his own eyes. Takumu was bullied throughout elementary school, possessing a scar on his neck from the beatings he would receive from the kendo team.