In Se7en (1995), the serial killer communicates under the name John Doe.
John Doe is an English-language placeholder used when a person’s identity is unknown or deliberately withheld. In the film, the name emphasizes that detectives William Somerset and David Mills are pursuing an unidentified killer whose crimes are organized around the seven deadly sins.
The investigation connects a sequence of elaborate murders with gluttony, greed, sloth, lust, pride, envy, and wrath. Kevin Spacey played the killer, but the character is credited as “John Doe,” not by a conventional personal name.
A frequent confusion is treating “John Doe” as a nickname like a criminal alias with a revealed legal identity. The film intentionally keeps that identity out of the story, making the placeholder part of its unsettling presentation. David Fincher directed the film, while Brad Pitt and Morgan Freeman played the detectives.