The Murder of Roger Ackroyd is a detective novel by the British writer Agatha Christie, her third to feature Hercule Poirot as the lead detective. The novel was published in the UK in June 1926 by William Collins, Sons, having previously been serialised as Who Killed Ackroyd? between July and September 1925 in the London Evening News. An American edition by Dodd, Mead and Company followed in 1926.

The novel was well-received from its first publication, and has been called Christie's masterpiece. In 2013, the British Crime Writers' Association voted it the best crime novel ever. It is one of Christie's best known and most controversial books, its innovative twist ending having a significant impact on the genre. Howard Haycraft included it in his list of the most influential crime novels ever written.