Dame Agatha Mary Clarissa Christie, Lady Mallowan, DBE (15 Sep 1890 – 12 Jan 1976) was an English writer. She is known for her 66 detective novels and 14 short story collections, particularly those revolving around her fictional detectives Hercule Poirot and Miss Marple. She also wrote the world's longest-running play, The Mousetrap, which was performed in the West End from 1952 to 2020, as well as six novels under the pseudonym Mary Westmacott. In 1971 she was appointed a Dame Commander of the Order of the British Empire (DBE) for her contribution to literature. Guinness World Records lists Christie as the best-selling novelist of all time. Her novels have sold roughly 3 billion copies, and her estate claims that her works come third in the rankings of the world’s most widely published books, behind only Shakespeare's works and the Bible. According to Index Translationum, she remains the most-translated individual author, having been translated into at least 103 languages. Her novel And Then There Were None is one of the top-selling books of all time, with approximately 100 million copies sold.

In 1955, Christie was the first recipient of the Mystery Writers of America's Grand Master Award. Later that year, Witness for the Prosecution received an Edgar Award for best play. In 2013, she was voted the best crime writer and The Murder of Roger Ackroyd the best crime novel ever by 600 professional novelists of the Crime Writers' Association. In September 2015, And Then There Were None was named the "World's Favourite Christie" in a vote sponsored by the author's estate. Most of Christie's books and short stories have been adapted for television, radio, video games, and graphic novels. More than 30 feature films are based on her work.