Walter Neff
Walter Neff manages to combine an engaging personality with a talent for the hard sell as a successful insurance salesman in 1940s Los Angeles. What begins as a routine house call with the intent to update a client's auto policy spins wildly out of the control the moment he sets his eye on the pretty blonde wife of the policyholder. A passionate affair quickly turns into a plot to collect a big insurance payout by killing the woman’s husband and making it look like an accident.
Phyllis Dietrichson
The sexy blonde in question is Phyllis, the second Mrs. Dietrichson. Mr. Dietrichson first met Phyllis when she was hired as a nurse to care for his first wife. The wife died under mysterious circumstances, and Phyllis quickly made the transition from nurse to bride. She is younger than her husband—not much older than his daughter—with a provocatively sexual streak and a decidedly sociopathic conscience. She easily lures Walter into her trap even while planning to betray him right from the beginning.
Barton Keyes
Keyes is the cagey claims adjuster who is both Walter’s immediate boss and his best friend. In fact, from what can be gathered from the film, he may well be Walter’s only friend. The circumstances of Mr. Dietrichson’s falling off a train—just after taking out an insurance policy that pays double in the case of that particular accident—sets off Keyes' alarms immediately. And Keyes is notorious for always being right when he follows his gut feeling. The affection he feels toward Walter is obvious, which makes their relation tragic as he gets closer and closer to fitting together the last pieces of the mystery of what happened on the train.
Mr. Dietrichson
The unfortunate Mr. Dietrichson could have avoided a whole mess of trouble simply by being a little more circumspect when hiring a nurse to care for his ailing wife.
Lola Dietrichson
Phyllis may have the power to enchant men into not looking very far past her provocative sexuality, but Lola was never fooled for a minute. She is certain that Phyllis murdered her mom, and she never for a minute accepts that her father’s death was an accident. Unaware of Walter’s role in that death, she tries to convince him that Phyllis is essentially evil personified. Ultimately, she manages to break the spell Phyllis holds on him.
Nino Zachetti
Nino is Lola's boyfriend, and he is poised to become yet another fly that gets trapped in Phyllis Dietrichson’s sticky web of evil. After killing Phyllis and dying of a gunshot wound himself, Walter strives for some small redemption by telling Nino to go back to the woman who truly loves him.
Mr. Norton
Mr. Norton is the boss and chief officer of Pacific All Risk Insurance Company, a superior to both Walter Neff and Barton Keyes. He erroneously believes the Dietrichson case was a suicide, laying out a grand theory, seemingly in order to prove to his employees that he has a first-rate intellect. However, Barton dismantles his entire theory straightaway.
Charlie
Charlie is the parking attendant in Walter Neff's building, who is instrumental to Walter's alibi. Walter makes sure to converse with him twice on the night of the murder to make it seem like he never left his apartment until the early morning.
Nettie
Nettie is the Dietrichson's maid, who originally tries to turn Walter away, thinking he is merely a meddlesome salesman. Although she is present in their first meeting, she is absent at their second meeting, the implication being that Phyllis intentionally sent Nettie away so that she could be alone with Walter.
The janitor
The janitor at the Pacific All-Risk Insurance office is one of the first characters we meet, letting an injured Walter into the Pacific All Risk Insurance building so that Walter can leave his dying confession into the Dictaphone. The janitor is also the one who notifies Barton Keyes of Walter's presence in the building after noticing that Walter was dripping blood.
