<P> Some writers have had prolific careers with hundreds of their works being published . While some best - selling authors have written a small number of books that have sold millions of copies, others have had lengthy careers and maintained a high level of output year after year . Dame Agatha Christie, the most - published novelist in history, is estimated to have sold 4 billion books, having written 69 novels and 19 plays . Her works were published between 1920 and 1976, equating to around three publications every two years . Dame Barbara Cartland has also sold millions of copies of her books but wrote many more than Christie . She spent 80 years as a novelist with 722 books published, averaging one book released every 40 days of her career . While Cartland wrote a significant number of full - length novels, other authors have been published many more times but have specialised in short stories . Spanish author Corín Tellado wrote over 4,000 novellas, selling 400 million copies of her books . </P> <P> Not all authors work alone . Groups of writers, sometimes led by one central figure, have published under shared pseudonyms . The Stratemeyer Syndicate, started by Edward Stratemeyer in 1905, created numerous book series including 190 volumes of The Hardy Boys and 175 volumes of Nancy Drew . More than 1,300 books were published by the group, and although Edward L. Stratemeyer wrote several hundred, he also employed ghostwriters to keep up with the demand . These writers were given storylines and strict guidelines to follow to ensure a level of consistency within each series . Amongst the writing team was Howard R. Garis, who contributed several hundred books to the collection, one of the most active authors . Sales were estimated at over two hundred million copies before the syndicate was sold to Simon & Schuster in 1984 . </P>

Who has written the most books in the world