Born Calliope and raised as a girl in Detroit, Cal is the child of second-generation Greek immigrants. He grows up near the automotive factories before his family moves to a suburban home on Middlesex Boulevard. As he enters adolescence, he discovers he is intersex. He eventually transitions to living as a man, moving away from his family to work at a club in San Francisco before finding employment as a cultural attaché in Berlin.

The matriarch of the Stephanides family who immigrates to the United States from Bithynios. She remains deeply connected to her old-world traditions, relying on her silver spoon to predict the future and keeping a silkworm box as a reminder of her past. She refuses to shop at American grocery stores and harbors deep anxieties about her family's choices, withdrawing into her bedroom in her later years.

Cal's grandfather and the patriarch of the Stephanides family. Unlike his wife, Lefty eagerly embraces his new American identity, finding work at the Ford Motor Company and later running a speakeasy called the Zebra Room. In his later years, he loses his voice following a stroke and becomes a quiet, devoted companion to his grandchildren.

Cal's father, a first-generation Greek American with a strong belief in science, progress, and the American dream. He serves in the military before transforming the family's old speakeasy into a highly successful restaurant chain, Hercules Hot Dogs. He is a pragmatic workaholic who constantly seeks upward mobility for his family.

Cal's mother, a beautiful and caring woman who grows up alongside Milton in Detroit. She initially dates a seminary student before realizing her true feelings for Milton when he leaves for World War II. She strives to be a supportive mother but often finds herself caught between her husband's ambitions and her children's changing needs.

Cal's older brother, playfully nicknamed by the narrator. He grows up as an energetic child and evolves into a countercultural college student who embraces the anti-war movement. He studies anthropology and adopts a Marxist perspective that clashes heavily with his father's capitalist values.

Cousin to Lefty and Desdemona. She lives in America with her husband, Jimmy, and helps the newly arrived immigrants assimilate. Independent and harboring her own secrets regarding her sexuality, she serves as a modern counterpoint to Desdemona's traditionalism.

Sourmelina's husband, an entrepreneurial figure who dabbles in various professions, including an illegal rum-running operation during Prohibition. He holds rigid views on gender roles, believing marriage is strictly for housekeeping and children. He displays intense jealousy regarding his wife, leading to a fateful drive over a frozen river.

An Armenian doctor who survives the destruction of his city and travels to America with the Stephanides siblings. He continues to serve as the family's physician in Detroit, though his medical knowledge eventually becomes outdated as he ages.

Milton's younger sister. She grows up in the shadow of the family's changing fortunes and eventually marries an Orthodox priest, leading a largely unhappy domestic life.

An Orthodox seminary student who later becomes a priest. Initially set up with Tessie, he represents stability and religious tradition, standing in sharp contrast to the more volatile Milton.

An American expatriate living in Berlin who takes photographs of factories. She is perceptive and patient, forming a mutual attraction with Cal that prompts him to open up about his past.

A wealthy, red-haired classmate of Cal's at the Grosse Pointe all-girls school. Rebellious and mercurial, she becomes the center of Cal's early romantic and sexual awakening.

The Obscure Object's privileged brother. He is confident and entitled, playing a disruptive role in Cal's relationship with his sister during a summer vacation.

A boy who attracts the attention of The Obscure Object. He spends time at the hunting lodge with the group during a summer vacation, serving as a catalyst for adolescent jealousy.

A prominent sexologist and expert in gender identity. He approaches Cal's condition with clinical detachment and heavily biased theories, prioritizing societal norms over his patient's actual biology and personal feelings.

Cal's childhood friend in the suburbs. Coming from a household with little parental oversight, she introduces Cal to early, exploratory childhood play.

A driver who gives Cal a ride to San Francisco. He owns a club called Sixty-Niners and provides Cal with a controversial opportunity to earn money upon arriving in the city.

A performer at Bob Presto's club who has androgen insensitivity. She forms a supportive friendship with Cal, helping him survive the harsh environment of the club and their shared marginalization.

An English teacher who encourages Cal's connection to Greek literature and casts the students in a production of *Antigone*.