Accelerator is the most powerful Psychic in Academy City. 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.
A sadistic boy about the same age as Tōma, 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.

His codename is Hei, which means black in Chinese. Hei is a very talented contractor, his Messier Code is BK-201. Hei lives two lives in the series. In public he is Li Shengshun, a foreign exchange student from China. He is very nice and well mannered. He lives in the Umitsuki apartments and is always working a new part-time job. He has a huge appetite and eats a lot, but never gets bigger.
Hei's other life is of a Contractor called BK-201 and also the Black Reaper, mostly by other Contractors. Before becoming a contractor Hei was an assassin which earned him his nickname. Hei is usually seen in a mask, that usually breaks, and a dark cloak that is bullet proof.
Hei has the ability to use electricity. His electricity goes through everything except air and concrete. He can kill anyone he wants, and short out power in large buildings. Hei can also disturb matter on a quantum level that can produce electricity. His weapon he most likely always uses is his knife on a metal, flexible wire. He usually wraps the wire around necks and arms, and electrocutes anyone he pleases. He is also seen putting his hand on a person's head and electrocuting them that way.

Ladd is a sadistic hit-man for the Russo family. His love for acts of violence truly shows in the maniacal glee he exhibits while fighting or killing. He is exceptionally skilled in hand-to-hand combat - particularly boxing -and the use of firearms. He is most happy while killing people that think they will never die and by seeing dead people or hearing gunfights. Ladd is deeply in love with his fiancée, Lua, although he expresses it through a passionate promise to kill her someday.

Enel thinks of himself as an invincible god - quite literally. He believes that he is a divine and immortal being, with the authority to do, take or destroy whatever he pleases. As the result, he appears fearless, childish, and without a care in the world. His lifestyle is relaxed and hedonistic, and when not attending to his godly duties of smiting the natives of Skypeia, he spends his time sleeping or eating (Enel's favourite fruit is apples) in his residence, being waited on hand and foot by beautiful women. This attitude carries over to his battles, where he's hardly serious and barely annoyed - instead he's relaxed, and enjoys himself by effortlessly absorbing attacks, and humiliating his opponents. In his fight against Kamakiri, he even went to sleep in the middle of the fight, in order to prove his immortality.

Hei i Enel