Hercule Poirot Novels:
* The Mysterious Affair at Styles (1920)
* The Secret Adversary (1922)
* Murder on the Links (1923)
* The Big Four (1927)
* The Murder of Roger Ackroyd (1926)
* Murder in the Mews (1937)
* Cards on the Table (1936)
* Death on the Nile (1937)
* Murder is Easy (1939)
* Appointment with Death (1938)
* Ten Little Niggers (1939) (originally titled "And Then There Were None")
* The ABC Murders (1936)
* Hercule Poirot's Christmas (1938)
* Murder in Mesopotamia (1936)
* Curtain (1975) - Poirot's last case
Miss Marple Novels:
* The Murder at the Vicarage (1930)
* The Body in the Library (1942)
* A Murder is Announced (1950)
* 4.50 from Paddington (1957)
* The Mirror Crack'd from Side to Side (1962)
* At Bertram's Hotel (1965)
* Nemesis (1971)
* Sleeping Murder (1976) - published posthumously
Other Detective Novels:
* The Secret of Chimneys (1925)
* The Big Four (1927)
* The Sittaford Mystery (1926)
* Lord Edgware Dies (1933)
* Why Didn't They Ask Evans? (1934)
* Crooked House (1949)
* The Pale Horse (1961)
* The Clocks (1963)
* Endless Night (1967)
Standalone Novels:
* The Secret of Chimneys (1925)
* The Sittaford Mystery (1926)
* The Big Four (1927)
* The Mystery of the Blue Train (1928)
* The Case of the Missing Will (1930)
* The Hound of Death (1933)
* The Thirteen Problems (1932)
* Dumb Witness (1937)
* The Daughter of Time (1951)
* Taken at the Flood (1953)
* Ordeal by Innocence (1958)
* The Man in the Brown Suit (1924)
* The Secret of the Blue Room (1926)
Short Story Collections:
* The Mysterious Mr. Quin (1930)
* The Case of the Missing Will (1930)
* The Thirteen Problems (1932)
* Poirot's Early Cases (1974)
* The Labours of Hercules (1947)
* Parker Pyne Investigates (1934)
* The Big Four (1927) - contains both a novel and short stories
* Dead Man's Folly (1956) - contains a novella and short stories
Plays:
* The Mousetrap (1952) - the world's longest-running play
* Spider's Web (1954)
* Witness for the Prosecution (1953)
* The Hollow (1955)
* Go Back for Murder (1948)
Romance Novels:
* The Secret Adversary (1922) - under the pseudonym Mary Westmacott
* The Rose and the Yew Tree (1923) - under the pseudonym Mary Westmacott
* Unfinished Portrait (1934) - under the pseudonym Mary Westmacott
* The Burden (1956) - under the pseudonym Mary Westmacott
* Giant's Bread (1930) - under the pseudonym Mary Westmacott
This is just a selection of Agatha Christie's work. For a comprehensive list, you can visit the Agatha Christie website or consult a bibliography.