Tom Ripley
Tom Ripley, a manipulative and clever but deeply unstable young man, agrees to go to Italy on behalf of his acquaintance Dickie Greenleaf's parents in order to convince Dickie to return home. There, Tom murders Dickie and assumes his identity, leading him to commit another murder in order to disguise his first one and to begin a series of complex maneuvers to evade discovery.
Tom's parents died when he was a child, and he is scarred by this trauma. He believes that he deserves luxury, status, and attention, and becomes resentful and bored when he does not receive them. At the same time, his homosexuality is evident to many of his peers, but Tom does not fully acknowledge it even to himself. His murder of Dickie, and his choice to disguise himself as his victim, stems from both a longing to possess and control the object of his subconscious desire and from a wish to have Dickie's money, status, and confidence. Though Tom ultimately gains all of Dickie's wealth and manages to go undiscovered by the police, his need for luxury and validation is more or less insatiable.
Dickie Greenleaf
Dickie is the son of Herbert Greenleaf, and Tom's first murder victim. While he is well-intentioned and generally kind, his privileged upbringing has not prepared him to deal with emotional complexity or harsh realities. He avoids his parents by living a perpetual vacation in Italy, where he works on his painting, which is mediocre. His closest friend in Italy, Marge, is in love with him, but he also avoids discussing this with her. When Tom arrives and also develops feelings for Dickie, Dickie alternates between ignoring his feelings and lashing out at him. In spite of these flaws, Dickie is well-liked, charming, and handsome, which makes Tom enjoy impersonating him.
Marge Sherwood
Marge is Dickie's closest friend in Italy and Tom's primary competitor for Dickie's love. She is well-meaning and sociable, and calls herself a writer, though it is unclear how serious she is about her own art. Marge's spontaneity and energy bother Tom, who believes, somewhat unfoundedly, that she is hopelessly naive and annoying. Marge has more opportunities than anyone else to realize that Tom has killed Dickie, since she knows both men well, and since she spent time with Tom directly after the murder. However, Tom manages to head off her suspicions at every turn, and she ultimately believes that her friend has committed suicide.
Herbert Greenleaf
Herbert Greenleaf is Dickie's father and a wealthy New York City shipbuilder. He is desperate to see his son again, especially since his wife is sick. Yet Greenleaf is unsure how to communicate with Dickie, leading him to ask Tom to do so on his behalf. Mr. Greenleaf is gruff but trusting and generous, and this, in combination with his desperation, leads him to not only send Tom to Italy, but also to give Tom a great deal of money. He never appears suspicious of Tom. However, Greenleaf clearly feels frustrated with his son, whose absence he considers an abandonment. Even when it seems that Dickie has either killed himself or gone into hiding, Greenleaf treats the disappearance as an act of stubborn inconsiderateness on his son's part.
Mrs. Greenleaf
Dickie's mother, and Herbert Greenleaf's wife, makes only a brief appearance on the page. Yet she is the driving force behind much of the book's action. Mrs. Greenleaf is suffering from leukemia, and wants to see her son before her condition worsens. Much like Marge, the most prominent female character in the book, Mrs. Greenleaf has a great deal at stake but seemingly little influence over the events that will determine her fate. While she longs to see Dickie, Dickie ultimately has the power to decide whether to return home. Mr. Greenleaf and Tom negotiate a plan to bring Dickie back to America. In the end, Mrs. Greenleaf doesn't get to see her son again, and isn't even privy to the truth about his disappearance. She and her husband believe that Dickie has chosen to either commit suicide or go permanently into hiding, assuming a new identity, when in truth he has been murdered. Therefore, Mrs. Greenleaf serves as a largely invisible reminder of the gravity of Tom's choices: by killing Dickie, he has not only ended one life but denied the last wish of a sick woman.
Freddie Miles
Freddie Miles is a friend of Dickie's from America. He is an outgoing man and an amateur playwright, seemingly, like Dickie and Marge, enjoying a life of leisure in Europe while working on an artistic hobby. Tom takes an immediate dislike to the talkative, red-haired Freddie. He murders Freddie out of panic when Freddie seems poised to learn about Dickie's murder. This murder, and the subsequent discovery of Freddie's body, heightens the stakes of Tom's plan.
Alvin McCarron
Mr. McCarron is the American detective who Mr. Greenleaf hires to help solve Dickie's case. He is a stout, straightforward man, uninterested in travel, luxury, or socializing—the very things that occupy so much of Tom's mind. Mr. McCarron does not seem particularly suspicious of Tom, but his feelings are difficult to discern, and he is not easily swayed by manipulation. Tom attributes his stoic exterior to his Irish heritage, presumably because of his Irish-sounding last name. Mr. McCarron appears competent, but is ultimately unable to solve his case.
Aunt Dottie
Tom's Aunt Dottie never appears in person within this book, but Tom spends a great deal of time thinking about her. After his parents drowned, Tom was sent to live with his aunt in Boston. Dottie treated him harshly and teased him about his sexuality, accusing him of being a "sissy." As an adult, Tom justifiably resents this, although his fury applies even in instances where Dottie has not been cruel—for instance, he feels righteously indignant because his aunt sends him small checks rather than the large ones he would prefer.
Cleo Dobelle
Cleo is the only person Tom knows in New York with whom he feels a deep and genuine connection. She lives with her parents, paints skillful miniature pictures with tiny brushes, and acts in a theatrical, bubbly manner. She is excited about and supportive of Tom's travel to Europe. Tom and Cleo have an intimate relationship, but without any romantic or sexual element.
Peter Smith-Kingsley
Peter is one of Tom's closest friends in Venice. An Englishman living abroad, he is friendly and generous. When Tom has a visible moment of emotional crisis at Peter's apartment because of his feelings of guilt, fear, and confusion in the wake of his murder spree, Peter comforts him, believing that Tom is merely grieving for his friend. Though the scene—and Peter's presence in the novel—is brief, this is the only instance in which another character responds to Tom's emotional turmoil after Dickie's death.