Agatha Christie 2 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. "And Then There Were None" is Christie's best-selling novel, with 100 million sales to date, making it the world's best-selling mystery ever, and one of the best-selling books of all time. Christie's stage play "The Mousetrap" holds the world record for longest initial run. It opened at the Ambassadors Theatre in the West End
Agatha Christie's fictional universe after Agatha Christie died, are included in the lists. Her novels under the pen name Mary Westmacott and her nonfiction books are not covered in this article. One notable example of characters from one novel appearing in another is the novel "The Pale Horse", which features Ariadne Oliver, Major Despard and his wife Rhoda (all had previously appeared on "Cards on the Table") and Mrs Dane Calthrop (from "The Moving Finger"). Outside of stories by Christie herself, adaptations of her works have also featured crossovers: Agatha Christie's fictional universe In Agatha Christie's mystery novels, several characters cross over different sagas,