Phyllis Dietrichson is the main antagonist in the two film adaptations of James M.Cain's novella Double Indemnity.
In the 1944 production, she was portrayed by Barbara Stanwyck; in the 1973 made-for-TV remake, by Samantha Eggar.
In both the novella and films, she convinces her insurance agent, Walter Neff (Fred MacMurray) to help her murder her husband. They make it appear that he fell off the back of a train by accident. This is done after they trick him into taking out a life insurance policy with a double indemnity clause, then murder him. The aim is to collect twice as much as normal from the insurance company.
The Dietrichson character was so iniquitous that Stanwyck, director Billy Wilder's first choice for the role, was reluctant to take it. Wilder was persistent, Stanwyck relented, and she said thereafter it was one of the best roles she'd ever played.
- The character was based upon real-life murderer Ruth Snyder. The photo of Snyder's execution in the Sing Sing electric chair, run on the cover of the January 13, 1928 New York Daily News with the one-word headline DEAD!, has been called the most famous newsphoto of the 1920s.
- It is also heavily implied that she killed her husband's first wife, Lola, as she died under mysterious circumstances while under Phyllis' care.
- The character was ranked as the #8 film villain of the first 100 years of American cinema by the American Film Institute in the AFI's100 Years...[[AFI's 100 Years... 100 Heroes and Villains.
- In the novella, the character was named Phyllis Nerdlinger, which was changed by the screenwriters, who thought it too comical.