Dame Edith Ngaio Marsh (23 April 1895 – 18 February 1982) was a renowned New Zealand writer and theatre director. She was a prominent figure during the "Golden Age of Detective Fiction" and is celebrated as one of the "Queens of Crime", alongside Agatha Christie, Dorothy L. Sayers, and Margery Allingham.

Marsh is best known for her character Inspector Roderick Alleyn, a gentleman detective of the Metropolitan Police in London. Over her fifty-year career, she authored thirty-two classic English detective novels that received international acclaim.

In addition to her writing, Marsh was an eminent Shakespearian producer. The Ngaio Marsh Awards are named in her honor and are awarded annually for the best New Zealand mystery, crime, and thriller fiction writing.