Dame Agatha Mary Clarissa Christie, Lady Mallowan, (née Miller; 15 September 1890 – 12 January 1976) was an English author known for her 66 detective novels and 14 short story collections, particularly those revolving around fictional detectives Hercule Poirot and Miss Marple. She is widely regarded as one of the greatest writers, particularly in the mystery genre. A writer during the "Golden Age of Detective Fiction", Christie has been called the "Queen of Crime"—a nickname now trademarked by her estate—or the "Queen of Mystery". She wrote the world's longest-running play, the murder mystery The Mousetrap, which has been performed in the West End of London since 1952. She also wrote six novels under the pseudonym Mary Westmacott. In 1971, she was made a Dame (DBE) by Queen Elizabeth II for her contributions to literature. She is the best-selling fiction writer of all time, her novels having sold more than two billion copies.

Christie was born into a wealthy upper-middle-class family in Torquay, Devon, and was largely home-schooled. She was initially an unsuccessful writer with six consecutive rejections, but this changed in 1920 when The Mysterious Affair at Styles, featuring detective Hercule Poirot, was published. Her first husband was Archibald Christie; they married in 1914 and had one child before divorcing in 1928.