What is the name of the serial killer in Fincher's Zodiac?

The serial killer in Fincher’s Zodiac is known as the Zodiac Killer. The name comes from letters sent to Bay Area newspapers by the unidentified murderer, who signed them with the symbol and name “Zodiac.”

David Fincher’s 2007 film dramatizes the investigation into the killings and the effort to identify the person behind the letters. It focuses especially on cartoonist Robert Graysmith, crime reporter Paul Avery, and San Francisco police investigators. The real killer murdered at least five people in Northern California between December 1968 and October 1969, while claiming responsibility for additional attacks.

The case remains officially unsolved. The killer’s letters included cryptograms, two of which were eventually deciphered: one in 1969 and another in 2020. “The Zodiac” is also a defensible shortened form, but “Zodiac Killer” is the standard canonical name used for the unidentified criminal and is the fairest quiz answer.