Agatha Christie was an essay writer.
Dame Agatha Mary Clarissa Christie , Lady Mallowan , DBE ( née Miller ; 15 September 1890 -- 12 January 1976 ) was an English crime novelist , short story writer and playwright . She is best known for her 66 detective novels and 14 short story collections , particularly those revolving around her fictional detectives Hercule Poirot and Miss Marple . Christie 's stage play The Mousetrap holds the world record for longest initial run .