Mildred Augustine Wirt Benson (born July 10, 1905 - died May 28, 2002) was an American author best known as an author of the Nancy Drew series of books under the pseudonym Carolyn Keene.

Mildred Benson wrote for the Stratemeyer Syndicate from 1929 to 1947, contributing to 20 of the first, originally published, Nancy Drew mysteries. She was one of 28 individuals who helped produce the Syndicate's Nancy Drew mystery books from 1929 to 1984. Edward Stratemeyer hired Mildred Benson in 1926 to assist in expanding his roughly-drafted stories with Syndicate directed, juvenile text in order to satisfy increasing demand for his series books.

Benson was born Mildred Augustine in Ladora, Iowa, and was married to Asa Wirt and, after Wirt's death, to George Benson , editor of the Toledo Blade newspaper of Toledo, Ohio. She was a graduate in journalism from the University of Iowa. She worked for 58 years as a journalist and was still writing a weekly column for the Toledo Blade at 96 at the time of her death.

Though the books in the Nancy Drew mysteries have sold over 200 million copies worldwide, none of the ghost writer contributors, such as Mildred Benson and her estate, receive any royalties. Published book rights were owned by the Stratemeyer Syndicate and are currently owned by Simon & Schuster. As with all Syndicate ghost writers, she was paid a flat fee of $125 to $250 for each Stratemeyer outline texted; the equivalent of three month's pay for a newspaper reporter at that time. At Edward Stratemeyer's death under the terms of his will, all Syndicate ghost writers, including Benson, were sent one fifth of the equivalent of the royalties the Syndicate had received for each book series to which they had contributed.

As with all Syndicate ghost writers, under the terms of her contract, Benson signed away all rights to her texting and any claim to the Syndicate pen name, Carolyn Keene. She was, however, permitted to reveal that she wrote for the Syndicate. This was required as the stories were owned and written by the Stratemeyer's, and they had to protect their Syndicate pen names and preserve series continuity as contributors to the series, came and went. Simon & Schuster currently maintain the same system.

However, in 1980 Mildred Benson's testimony which she offered in a court case involving the publishers revealed her identity to the public as a contributor to the Nancy Drew mystery stories. With only this and without access to Stratemeyer Syndicate archives now held at the New York Public Library, the public presumed that she had a primary authorship claim to the Nancy Drew stories and pen name, Carolyn Keene, who also "wrote" the Dana Girls series.

The character of Nancy Drew was conceived by Edward Stratemeyer and he wrote the first five mystery stories. Mildred Benson was the first ghost writer to expand Edward's roughly-drafted Nancy Drew plots with directed juvenile texting. Texting was then edited and rewritten as required, and the Syndicate approved and had all final books published under the Syndicate's name. Subsequent Nancy Drew stories (with two exceptions), for which Benson provided texting, were all written by Edna Stratemeyer Squier and, primarily, Harriet Stratemeyer Adams, after their father's death in 1930.

Benson's favorite Nancy Drew story was The Hidden Staircase.