Agatha May Clarissa Miller was born in Devon in 1890, the youngest child of a wealthy family. She was taught by a governess and never attended school. The novelist Eden Phillpotts, who lived nearby, acted as a mentor, guiding her reading and encouraging her to write. At 16, she attended finishing school in Paris and then spend three months in Egypt. Agatha was a talented pianist and singer and spoke French and German.

In 1914, she married Archie Christie, a fighter pilot. Their only child, Rosalind, was born in 1919. While Archie was at War, Agatha worked as a nurse and wrote her first detective story, The Mysterious Affair at Styles. This book introduced the character of Hercule Poirot who was to feature in 30 of Agatha Christie's novels. Although the book was completed in 1915, it was not published until 1920.

Agatha Christie's second book, The Secret Anniversary, was published in 1922 and became a best seller. From that time, she produced at least one book a year and remained on the best-seller list for the rest of her life. The Murder of Roger Ackroyd, generally regarded as her masterpiece was published in 1926.

In 1926, Agatha's mother died and, shortly afterwards, Archie asked for a divorce in order to marry another woman. Agatha disappeared for a period of three weeks causing enormous public speculation. When found in a small hotel, she claimed to have lost her memory.

In 1930, she married Max Mallowan, an archaeologist, who she later often assisted on archaeological digs in Iraq and Syria. 

At about this time she introduced her second famous character, Miss Jane Marple, into her stories. Miss Marple featured in thirteen of Agatha Christie's novels beginning with Murder at the Vicarage.

in 1952, her short story, Three Blind Mice, which had previously been adapted as a radio play, opened as the stage play, The Mousetrap. It holds the record as the longest running play ever produced.

In all, Agatha Christie wrote 80 mystery novels and short story collections and 14 plays. She also wrote a series of six romantic novels under the penname of Mary Westmacott and four other books. Her books have sold more than a billion copies in English and another billion in 45 other languages.

In 1956, Agatha Christie was awarded a CBE. In 1968, her husband was knighted for his work in archaeology giving them the titles of Sir Max and Lady Mallowan. In 1971, Agatha Christie became a Dame of the British Empire. She died in 1976.