Kinsey Millhone

Grafton had been fascinated by mysteries series whose titles were related, such as John D. MacDonald's Travis McGee series, each of which included a color in the title, and Harry Kemelman's Rabbi Small series, each of which included a day of the week in the title. While reading Edward Gorey's The Gashlycrumb Tinies, a picture book with an alphabetized list of ways for children to die, Grafton decided to write a series of novels whose titles would follow the alphabet. She immediately sat down and made a list of all of the crime-related words that she knew.

These became the series now known as the "alphabet novels", featuring sleuth and private investigator Kinsey Millhone. The series is set in Santa Teresa, a fictionalized version of Santa Barbara. Grafton followed the lead of Ross Macdonald, who created the fictional version of the city. Grafton described Kinsey Millhone as her alter ego, "the person I might have been had I not married young and had children."

The series begins with "A" Is for Alibi, published and set in 1982. "B" Is for Burglar, followed, then "C" Is for Corpse, each novel's title combining a letter with a word, except X. After the publication of "G" Is for Gumshoe, Grafton was able to quit her screenwriting job and focus on her writing. Since the publication of "A" is for Alibi, a new episode was released each year or so.[19] The name of each book was a source of speculation. In May 2009, Grafton told Media Bistro that she was "just trying to figure out how to get from "U" is for Undertow to "Z" Is for Zero" and that "just because she knows the endgame title for Z [...] doesn't mean she knows what V, W, X, and Y will be". Grafton said that the series would end with "Z" Is for Zero, but she died before she could begin writing it. Her daughter said Grafton would never allow a ghostwriter to write in her name and "as far as we in the family are concerned, the alphabet now ends at Y."