Sad Cypress is a work of detective fiction by British writer Agatha Christie, first published in the UK by the Collins Crime Club in March 1940 and in the US by Dodd, Mead and Company later in the same year.
The novel was the first novel in the Poirot series set at least partly in the courtroom, with lawyers and witnesses exposing the facts underlying Poirot's solution to the crimes. The title is drawn from a song in Shakespeare's play Twelfth Night.
The novel was well received at publication. One reviewer remarked "it is economically written, the clues are placed before the reader with impeccable fairness, the red herrings are deftly laid and the solution will cause many readers to kick themselves." Another reviewer found the story to be well told, but did not like that the plot "turns on a legal point" that is misconceived. A later review described it as "Elegiac, more emotionally involving than is usual in Christie, but the ingenuity and superb clueing put it among the very best of the classic titles."