A Changer – a member of a near-extinct humanoid species capable of altering their physical appearance to perfectly mimic others. Working as an agent for the Idirans in their war against the Culture, Horza is driven by a deep philosophical opposition to machine-led civilisation, believing the Culture's AI Minds represent a fundamental threat to biological life.

One of Special Circumstances' foremost agents, recruited from outside the Culture to change the destiny of planets through intrigue, dirty tricks, and military action. A man of extraordinary capability haunted by a past he cannot escape.

Chief bodyguard to the Protector General, a man who seized power through regicide. DeWar is devoted to his charge, skilled in combat, and haunted by memories of a different life.

Born a princess of the Sarl, a feudal people living within a vast artificial Shellworld. She left her homeworld to join the Culture and became a Special Circumstances agent. Now she must return to the world she thought she had left behind.

A Sarl prince, eldest surviving son of the king. Vain and pampered, Ferbin is forced to flee his home after witnessing a crime that overturns everything he believed about his father's most trusted ally.

One of the Culture's greatest Game Players, a master of every board, computer, and strategy game known to civilisation. Brilliant but restless, bored by the ease of his success and searching for a challenge worthy of his abilities.

One of the Intagliated – her entire body marked with an intricate tattoo that signifies her family's debt and her status as property. Determined to win her freedom at any cost, her release comes at a price that draws her into a conflict far larger than her personal vendetta.

A Chelgrian military officer carrying a grief so profound it has hollowed him out. Sent to the Culture Orbital Masaq' on an ostensibly diplomatic mission, he carries with him a purpose known only to the leaders of his civilisation.

Doctor Vosill's young apprentice and assistant, and the first-person narrator of the Doctor chapters. An orphan of Koetic parents killed during the Imperial sacking of Derla, he was raised among officers' orphans. Devoted to Vosill, he secretly reports on her to Guard Commander Adlain. He later becomes a renowned physician, Principal of the Medical University of Haspide, and the King's personal doctor.

The King's personal physician, a woman of mysterious origin whose medical knowledge far surpasses anything available in the feudal society she serves. She has more enemies at court than she initially realises, and more resources than they suspect.

A lieutenant commander of the Gzilt military and an accomplished musician attempting to master a piece of music written for a four-armed player. When the Gzilt Regimental High Command is destroyed on the eve of the civilisation's Subliming, Cossont is drawn into a desperate search for answers.

The richest man in the Enablement, Lededje's owner. Charming in public, monstrous in private, his lust for power extends beyond his own world into the digital realms where the dead are stored.

The avatar of the GSV Sleeper Service - a tall, angular, black-dressed, cadaverous creature. Awkward and sometimes childlike in manner, Amorphia serves as the ship's physical representative during its interactions with Dajeil Gelian and later Genar-Hofoen. It reveals the ship's true nature as a secret SC weapon disguised as an Eccentric.

The oldest member of Kraiklyn's Free Company, Aviger is a cautious, somewhat anxious mercenary who often voices the crew's collective nervousness. He serves loyally through the mission to Schar's World but is killed by Xoxarle when the Idiran breaks free.

A short, fair, powerfully built knight in tyl Loesp's service who stood guard during King Hausk's murder. More impulsive and violent than his partner Vollird, Baerth draws his sword rashly when confronting Ferbin on the Surface and is disarmed by a Nariscene. Assigned with Vollird to guard Oramen at the Falls, he dies in the collapse caused by their assassination attempt.

The avatar of the Culture ship Mistake Not..., initially appearing androgynous with bronze skin before reshaping into a handsome Gzilt male. Resourceful, witty, and capable in combat, Berdle accompanies Cossont through her mission to find QiRia's mind-state and memories. Destroyed in the final battle aboard the Equatorial 353 while protecting Cossont from Colonel Agansu's android.

Prin's mate and fellow activist who enters the Pavulean Hell with him. The experience breaks her psychologically; she denies the existence of any reality beyond Hell and refuses to activate her escape code. Her virtual self remains trapped in Hell after Prin escapes, while her sleeping physical body is eventually woken without the Hell memories.

An ancient drone and long-time friend of the Seich family on Phage Rock, with personality elements dating back nine thousand years. It accompanies Ulver on her SC mission, serving as her chaperone and advisor. Practical and exasperated by Ulver's behaviour, it ultimately transfers to the Grey Area before returning to Phage.

A highly augmented Gzilt special forces officer under Banstegeyn's command, originally of the Home System Regiment. Carries out the destruction of General Reikl's surviving forces at Izenion, later attacks the Incast facility on Bokri where he is badly injured. His consciousness is transferred to an android body for the final assault on the Equatorial 353, where he is killed by the Mistake Not...'s nanomissiles.

A Chelgrian composer of extraordinary talent, living in self-imposed exile on Masaq' Orbital. He fled Chelgrian society in disgust at its caste system and has no desire to return or to engage with his homeland's politics.