Agatha Christie: The Hercule Poirot Mysteries

Main Character: Hercule Poirot, Belgian private investigator
Setting: mostly England
Bold type indicates a book I've read.

The Mysterious Affair at Styles (1920)
Murder on the Links (1923)
Poirot Investigates (1924)
The Murder of Roger Ackroyd (1926)
The Big Four (1927)
The Mystery of the Blue Train (1928)
Peril at End House (1932)
Thirteen at Dinner (1933)
Murder on the Orient Express (1934), aka: Murder in the Calais Coach
Murder in Three Acts (1935)
Death in the Air (1935), aka: Death in the Clouds
The A.B.C. Murders (1935)
Murder in Mesopotamia (1936)
Cards on the Table (1936) Poirot / Ariadne Oliver  [see review]
Poirot Loses a Client (1937), aka: Dumb Witness
Death on the Nile (1937)
Dead Man's Mirror (1937)
Appointment With Death (1938)
A Holiday for Murder (1938), aka: Murder for Christmas
The Regatta Mystery (1939)
Sad Cypress (1940)
The Patriotic Murders (1940)
An Overdose of Death (1940), aka: One, Two, Buckle My Shoe
Evil Under the Sun (1941)
Murder in Retrospect (1943), aka: Five Little Pigs (1942)
Murder After Hours (1946)
The Labours of Hercules (1947)
There is a Tide (1948), aka: Taken at the Flood 
Witness for the Prosecution & Other Stories (1948)
Mousetrap & Other Stories (1950)
The Underdog and Other Stories (1951)
Mrs. McGinty's Dead (1952) Poirot / Ariadne Oliver
Funerals Are Fatal (1953), aka: After the Funeral
Hickory, Dickory, Death (1955)
Dead Man's Folly (1956) Poirot / Ariadne Oliver
Cat Among the Pigeons (1959)
The Adventure of the Christmas Pudding (1960)
Double Sin and Other Stories (1961)
The Clocks (1963)
Third Girl (1966) Poirot / Ariadne Oliver
Hallowe'en Party (1969) Poirot / Ariadne Oliver
Elephants Can Remember (1972) Poirot / Ariadne Oliver [see review]
Hercule Poirot's Early Cases (1974)
Curtain (1975)