Roderick Alleyn is the policeman hero of how many detective novels of Ngaio Marsh?

Roderick Alleyn is a fictional character who first appeared in 1934. He is the policeman hero of the 32 detective novels of Ngaio Marsh. Marsh and her gentleman detective belong firmly in the Golden Age of Detective Fiction, although the last Alleyn novel, Light Thickens, was published in 1982.

Marsh mentions in an introduction that she named her detective Alleyn after the Elizabethan actor Edward Alleyn, founder of Dulwich College, where her father had been a pupil. She started a novel with Alleyn in 1931, after reading a detective story by Agatha Christie or Dorothy L. Sayers on a wet Saturday afternoon in London and wondering if she could write something in the genre. So she bought six exercise books and a pencil at a local stationer and started A Man Lay Dead, involving a Murder Game, which was then popular at English weekend parties.

Dame Ngaio Marsh DBE (/ˈnaɪ.oʊ/; 23 April 1895 – 18 February 1982), born Edith Ngaio Marsh, was a New Zealand crime writer and theatre director. She was appointed a Dame Commander of the Order of the British Empire in 1966.

Marsh is known as one of the "Queens of Crime", along with Agatha Christie, Dorothy L. Sayers, and Margery Allingham. She is known primarily for the character of Roderick Alleyn.