Dame Agatha Christie, DBE (15 September 1890 – 12 January 1976), was a British crime writer of novels, short stories and plays. She also wrote romances under the name Mary Westmacott, but she is best remembered for her 80 detective novels—especially those featuring Hercule Poirot and Miss Jane Marple—and her successful West End theatre plays.

Guinness Book of World Records claims she is the best-selling writer of books of all time and, with William Shakespeare, the best-selling author of any kind. Only the Bible has sold more than her roughly four billion copies of novels. According to UNESCO, Christie is the most translated individual author, with only the collective corporate works of Walt Disney Productions surpassing her. Christie's books have been translated into at least 103 languages.

Christie's stage play The Mousetrap holds the record for the longest initial run: it opened at the Ambassadors Theatre in London on 25 November 1952 and as of 2010 was still running after more than 23,000 performances. In 1955, Christie was the first recipient of the Mystery Writers of America's highest honour, the Grand Master Award, and in the same year Witness for the Prosecution was given an Edgar Award by the MWA for Best Play. Most of her books and short stories have been filmed, some many times over (Murder on the Orient Express, Death on the Nile and 4.50 From Paddington for instance), and many have been adapted for television, radio, video games and comics.

In 1968, Booker Books, a subsidiary of the agri-industrial conglomerate Booker-McConnell, bought a 51 percent stake in Agatha Christie Limited, the private company that Christie had set up for tax purposes. Booker later increased its stake to 64 percent. In 1998, Booker sold its shares to Chorion, a company whose portfolio also includes the literary estates of Enid Blyton and Dennis Wheatley.

In 2004, a 5,000-word story entitled The Incident of the Dog's Ball was found in the attic of the author's daughter. This story was the original version of the novel Dumb Witness. It was published in Britain in September 2009, alongside another newly discovered Poirot story called The Capture of the Cerberus, in John Curran's Agatha Christie's Secret Notebooks: Fifty Years Of Mysteries. On November 10, 2009, Reuters announced that The Incident of the Dog's Ball will be published by The Strand Magazine.