Hank is a 33-year-old mail carrier who contends with the grueling bureaucracy of the US Postal Service. He relies heavily on alcohol and gambling to manage the physical and mental toll of his menial labor. Defiant by nature, he consistently refuses to conform to institutional expectations, choosing instead to clash with oppressive supervisors and preserve his personal autonomy.

Betty is Hank's girlfriend during his early years working for the post office. She shares his destructive habits, frequently drinking late into the night and disappearing for days at a time. Despite their instability, she offers Hank a measure of companionship in an otherwise alienating world.

Joyce is a 23-year-old heiress from a small town in Texas. She is wealthy, impulsive, and highly demanding, contrasting sharply with Hank's world-weary attitude. Her desire to prove her independence to her family constantly disrupts their living situation, moving them from rural Texas back to Los Angeles.

Jonstone is a cruel and vindictive postal supervisor whom the carriers call "The Stone." He takes pleasure in his authority, frequently assigning the most difficult routes to workers who displease him. He embodies the crushing, impersonal bureaucracy that demands total obedience from its laborers.

George is a veteran mail carrier in his late sixties with more than 40 years of service. He is quiet, physically worn down by decades of repetitive motion, and finds small joy in giving candy to children on his route. His career takes a sudden downturn after a neighborhood misunderstanding.

Tom is a substitute mail carrier who works under Jonstone's harsh supervision. Initially sharing Hank's resentment toward the postal management, his career trajectory ultimately forces him to make practical choices to support his growing family.

Fay is an older, gray-haired woman who protests the war and frequently attends writers' workshops. She moves into Hank's apartment, bringing a casual disregard for domestic order that often frustrates him. She relies on alimony and her mother's support while pursuing her political and artistic interests.

David is a younger postal clerk and an aspiring romance novelist. He complains constantly about his personal life in a booming voice and seeks endless validation for his writing, refusing to accept constructive criticism.

Mary Lou is a woman Hank rescues from track security by pretending to be her husband. Their fast-paced, passionate encounter at an oceanfront motel brings unexpected complications.

Hector is a small, aggressive man who involves himself in Mary Lou's affairs. He initiates a violent altercation that leaves a lasting impact on Hank's sense of security.

Vi is a light-skinned Black woman who works at the central post office. She invites Hank to her apartment, cooks for him, and attempts to foster intimacy, though his heavy drinking interferes with their connection.

Wally is Joyce's wealthy grandfather. He maintains a welcoming but slightly mischievous attitude toward Hank, occasionally setting up practical jokes, such as a surprise encounter with charging buffalo.

"Purple Stickpin" is the nickname Hank gives to a suave man at Joyce's workplace. He practices rehearsed gentlemanly gestures that easily win Joyce's infatuation, despite Hank's warnings about office romances.

Miss Graves is an employee at the personnel office who reviews Hank's employment applications. She represents the bureaucratic hurdles Hank must clear to maintain his position at the post office.

Eddie "Skinny" Beaver is a post office counselor tasked with enforcing the strict time standards for sorting mail. He views employees purely as units of production and strictly forbids any deviation from the rules.

Helen is a post office nurse who conducts home checks on employees and treats workplace injuries. She maintains a professional but slightly playful demeanor when bandaging Hank's burned hands.

Parker is Hank's union representative at the post office. He collects union dues but offers only minor, often absurd explanations for management's decisions, embodying the ineffectiveness of formal labor protections.

Larry is Betty's estranged adult son who drives a luxury car. He maintains a distant relationship with his mother and handles the logistics of family emergencies with an air of detachment.

Marina is the infant daughter of Hank and Fay. Her existence brings out a rare, tender side of Hank, and her departure with her mother leaves a significant void in his life.

Matthew is a highly praised mail carrier who secretly steals donation money from letters intended for a religious temple. His eventual arrest shocks the postal community.

Gus is a former third-ranked welterweight boxer who knows Hank. They share a quick drink before Hank attends his postal training sessions.