Age: 15-16
Height: 168 cm
Hair color: white
Eye color: red
Classification: Esper
Affiliation: GROUP (Former operative)
Occupation: Nagatenjouki Academy
Level: 5
Partner: Last Order
Ability: Vector Manipulation
Quote: "Just because I've gotten weaker, it doesn't mean that you got stronger, right?"
Theme Song: "Saikyou no Nanori"

Accelerator is the most powerful Psychic in Academy City and the main protagonist of Toaru Kagaku no Accelerator. His real name is unknown, though Accelerator recalls his surname was composed of two characters and his given name consisted of three characters. First appearing as an antagonist of the third light novel, he later becomes a main character and the lead of the science side in the Toaru Majutsu no Index series, especially in volumes 5, 8, 12, 13, SS1, SS2, 15, 14, 19, and 20.

A sadistic boy about the same age as Touma, he has an ability called "Vector Change," a form of telekinesis allowing him to change the vector values of anything he touches due in part of having a thin coat of AIM fields surrounding his body. This ability allows Accelerator perform feats such as reversing the blood flow inside a person's body, increasing the wind velocity around him to create a massive plasma storm, and blocking sound. His ability is automatic, which means that he must consciously allow gravity to affect him and that his body blocks all ultraviolet radiation, resulting his albino appearance (white hair and pale skin) because his body is unable to make melanin. The automatic nature of Redirection also prevents the use of projectiles (like bullets) and explosives (like bombs) against him.

Accelerator's unique ability made him the subject of an experiment attempting to create the first Level 6 ESPer; according to the city's best supercomputer, Tree Diagram (which was unprecedentedly destroyed by Index's Dragon Breath), this feat could only be achieved by killing 128 skilled Level 5 ESPer without a single failure. Since there are only six other known Level 5s in Academy City, an alternative plan was formed to "level up" Accelerator by having him kill 20,000 skilled Level 3 ESPers: the Misaka clones. He willingly joins the experiment to gain a reputation as the most powerful and feared ESPer that no one would be foolish enough to challenge and even killed many who got in his way.