Sophie Fevvers is a world-renowned aerialist known as the "Cockney Venus," famous for possessing a pair of swan wings she claims are completely genuine. Raised in a London brothel after being abandoned as a baby, she constructs a larger-than-life, boisterous public persona. She is fiercely independent and highly intelligent, constantly controlling how audiences perceive her physical marvels to maintain her own agency.

Jack is a pragmatic investigative journalist from London who is described as a blank slate, lacking a strong personal identity. Driven by skepticism, he joins Colonel Kearney's circus undercover as a clown to discover the truth behind Fevvers's supposed anatomical marvel. His pursuit of a good story throws him into the chaotic world of circus performers, forcing him to reconstruct his understanding of reality.

Lizzie is Fevvers's middle-aged foster mother and constant companion. A former sex worker and fierce political radical, she possesses what Fevvers calls "household magic" which is actually an advanced understanding of physics and thermodynamics. She acts as a grounded, sharp-witted anchor for Fevvers's soaring ambitions.

Colonel Kearney is a flamboyant American from Kentucky who owns a massive traveling circus. Dressed in stars and stripes, he is obsessively driven by the "Ludic Game," seeking to conquer the global entertainment market by taking his performers across Russia to Japan.

Buffo is the oldest, most experienced clown in Colonel Kearney's circus and the unofficial leader of Clown Alley. He views the clown as a tragic, Christ-like figure who absorbs the audience's suffering through relentless self-humiliation. He struggles heavily with alcohol to cope with the psychological toll of his performance.

Mignon is a deeply traumatized but remarkably gifted singer who only speaks German. After a tragic childhood and years of being used by a con man, she ends up in the circus married to an abusive ape-keeper. With the help of the other women in the circus, she begins to find her voice and a safe place.

The Princess is a silent, elegant woman who performs a dangerous circus act, playing the piano while captive tigers dance. She maintains a tense, fearful relationship with her animals, keeping a loaded gun nearby. She finds unexpected joy when paired with a new musical partner.

Samson is the heavily muscled strongman of the circus troupe. Though physically imposing, he proves emotionally fragile, particularly when navigating his romantic entanglements within the tight-knit circus community.

The Professor is a highly intelligent ape whose cognitive abilities rival those of humans. He leads the "Educated Apes" act and possesses a sharp understanding of labor rights, eventually organizing to improve conditions for his fellow apes.

Lamarck is the chronically drunk, violently abusive ape-keeper of the circus. His lack of care for his animals and his horrific treatment of his wife lead to his eventual downfall within the troupe.

Ma Nelson is the eccentric, imperious proprietor of the London brothel where Fevvers is raised. Dressed like an admiral, she treats her establishment as a place of safety and education for women, fostering an environment where they study politics and art.

Madame Schreck operates a bleak, exploitative museum dedicated to abnormal women. She uses women with physical differences in highly structured exhibition acts, keeping their wages and treating them as pure commodities for male patrons.

Rosencreutz is a wealthy, mentally unsound man harboring perverse occult beliefs. He wears a golden medallion and seeks to achieve immortality through a twisted ritual involving Fevvers, whom he views as the "Angel of Death."

The Grand Duke is a fabulously wealthy Russian aristocrat with an intense obsession for Fevvers. He collects mechanical toys and jeweled eggs, attempting to add Fevvers to his collection of possessed objects by trapping her in his estate.

Olga is an imprisoned woman at an isolated Russian corrections house. Having killed her abusive husband to protect herself and her son, she maintains a strong internal sense of justice and maternal devotion, which gives her resilience against the prison's harsh conditions.

The Countess runs an isolated Russian female corrections house. Having gotten away with poisoning her own husband, she projects her deep-seated guilt onto the inmates, enforcing an environment of absolute silence and constant surveillance from her rotating chair.

Vera is a hooded guard at the Russian corrections house. Although forbidden to speak or interact with the prisoners, she works under a strict system designed to isolate both inmates and guards, eventually challenging those very rules.

The Shaman is a spiritual leader of an isolated Siberian tribe. Though fully aware that he uses sleight-of-hand and hallucinogens to maintain his authority, he genuinely believes his rituals serve a greater truth for his people.

The Escapee is an educated convict and political radical stranded in the Siberian wilderness. He is entirely focused on building a utopian future and applies a highly organized, forward-thinking mindset to his survival.

The Maestro is an eccentric old man living alone in a cabin in the Siberian taiga. Lured into the wilderness by false promises of untapped musical talent, he maintains an isolated existence with only his piano for company until visitors arrive.

Sybil is Colonel Kearney's incredible companion pig, capable of communicating in English by pointing at alphabet cards. She acts as a shrewd advisor to the Colonel on major business decisions.

Isotta is Lizzie's sister who lives in Battersea. She runs a family ice-cream shop and provides a temporary home for Lizzie and Fevvers during a period of severe financial hardship.

Sleeping Beauty is a woman exhibited at Madame Schreck's museum who suffers from a condition that keeps her asleep for almost the entire day. She is constantly observed by patrons as a living statue.

Herr M is a con man who pretended to be a spiritual medium communicating with the dead. He used Mignon as an actor in his elaborate scams without paying her a salary, keeping her isolated in his apartment.

Ivan is a young Russian boy cared for by his grandmother in St. Petersburg. He is the son of an imprisoned murderess, growing up separated from his mother.

Esmerelda is a former worker at Ma Nelson's brothel who manages to escape into a new life. She serves as a vital connection for Fevvers, eventually introducing her to Colonel Kearney and the circus.