A restless, curious young man from a disadvantaged Jewish immigrant background in Chicago. With an insatiable yearning for experience and self-discovery, he floats through various jobs, relationships, and schemes. He possesses a strong sense of independence and constantly resists others' attempts to mold his identity or tether him down.

A wealthy, adventurous, and impulsive heiress who falls deeply for Augie. She is fiercely independent and eccentric, harboring grandiose plans that include moving to Mexico to train an eagle to hunt iguanas. She projects her own romanticized ideals onto Augie, creating a demanding dynamic between them.

Augie's ambitious and pragmatic older brother. Determined to escape poverty by any means necessary, he focuses entirely on acquiring wealth and social status. He acts as a foil to Augie, willing to sacrifice emotional fulfillment and personal authenticity in exchange for financial security.

A wealthy real estate tycoon who runs a multitude of questionable business operations. Despite a physical disability that requires him to use a wheelchair, he possesses boundless energy, intellect, and ambition. He becomes a significant early influence on Augie, teaching him how to manipulate the bureaucracies of the adult world.

An elderly, autocratic Russian woman who lives with the March family. Though not biologically related, she acts as the family's matriarch and aggressively shapes the boys' upbringing. A Machiavellian figure, she teaches Augie the art of deception and manipulation as tools for survival against institutions.

Augie's younger brother, who has a developmental disability. He is deeply loved by his family, particularly Augie and his mother, though his need for specialized care creates tension within the household and leads to fierce disagreements about his future.

A meek, loving, and visually impaired woman who defers completely to Grandma Lausch's dominating personality. Left to raise her sons alone, she relies on charity and her own meager earnings, profoundly feeling the separation of her family as the boys grow up.

A frank, independent young woman who becomes one of Augie's truest friends. She experiences a volatile relationship with a communist professor, but she and Augie share a bond rooted in honest conversation and mutual support during crises.

A beautiful young American actress who crosses paths with Augie. Like him, she feels like someone whom others constantly try to fit into their own schemes. She harbors secrets about her debts and past relationships.

A wealthy coal heiress. She is fully aware that Simon's pursuit of her is financially motivated, yet she genuinely cares for him. She represents the upper-class stability and affluence that Simon desperately craves.

An aristocratic woman from Luxembourg who takes Augie on as her personal project. Hoping to mold him into a cultured gentleman of high society, she attempts to dictate his lifestyle and even proposes formally adopting him.

The owner of a sporting goods shop in an affluent Chicago suburb. He provides Augie with early employment but defers to his wife's grander schemes for the young man.

Augie's childhood friend whose comparatively wealthy but chaotic household offers an alternative view of family life. He encourages Augie's early experimentation with petty theft.

A large, foul-smelling, and largely uncooperative bald eagle. Intended to be a fierce hunter of iguanas, the bird fails to meet Thea's grandiose expectations and serves as a significant source of tension during the Mexican expedition.

An erratic and highly self-confident scientist whom Augie encounters during wartime. He possesses bizarre, outlandish theories about creating new forms of life and is fiercely determined to defect to the Canary Islands to continue his experiments.

A jaded, perceptive Armenian lawyer and black-market trafficker. He offers Augie profound advice regarding secrecy, authenticity, and the nature of identity.

A theater owner and committed communist who frequently crosses paths with Augie throughout his life. He struggles with social ostracization due to his politics and later takes a job as a bodyguard for Leon Trotsky.

Charlotte's wealthy cousin. She briefly dates Augie at Simon's urging, representing the kind of financially beneficial match Augie ultimately rejects.

A melancholy and brilliant Latin and algebra teacher. He frequently converses with Augie about life and marriage, offering him advice while dealing with his own familial and financial problems.

A graduate student and communist who engages in a volatile romance with Mimi. He eventually takes a job working as a secretary for Leon Trotsky in Mexico.

Einhorn's brother, who briefly employs Augie to help manage a boxer. He provides Augie with protection from petty criminals but ultimately lacks his brother's keen business sense.

An old college friend of Augie's who runs an illicit racket stealing and reselling textbooks. He lives a pragmatic life and occasionally assists Augie during medical emergencies.

A hotel maid who strikes up a casual romantic relationship with Augie. Despite being engaged to someone else, she maintains an ongoing connection with him.