Agatha Christie: The Miss Marple Mysteries

Main Character: Miss Jane Marple, elderly spinster and amateur sleuth
Location: St. Mary Mead and other locales, mostly in England
Bold type indicates a book I've read.

1. Murder at the Vicarage (1930)
2. The Tuesday Club Murders (1932), aka: The Thirteen Problems
3. The Regatta Mystery (1939)
4. The Body in the Library (1942)
5. The Moving Finger (1943)
6. Mousetrap & Other Stories (1950)
7. A Murder is Announced (1950)  [See Review]
8. Murder with Mirrors (1952), aka: They Do It With Mirrors
9. A Pocket Full of Rye (1953)
10. What Mrs. McGillicuddy Saw (1957), aka: 4:50 from Paddington
11. The Adventure of the Christmas Pudding (1960)
12. Double Sin & Other Stories (1961)
13. The Mirror Crack'd (1962), aka: The Mirror Crack'd From Side to Side
14. A Caribbean Mystery (1964)
15. At Bertram's Hotel (1965)
16. Nemesis (1971)
17. Sleeping Murder (1976)

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)

Agatha Christie: The Superintendent Battle Mysteries

Main Character: Scotland Yard's Superintendent Battle. To be accurate, Superintendent Battle is not so much a main character as he is a unifying element in this series of books. He also appears in the Hercule Poirot mystery, Cards on the Table.
Setting: England
Bold type indicates a book I've read.

The Secret of Chimneys (1925)
The Seven Dials Mystery (1929)
Murder is Easy (1939), aka: Easy to Kill
Towards Zero (1944), aka: Come and Be Hanged

Simon Brett: The Charles Paris Mysteries

Main Character: Charles Paris, British actor and amateur sleuth
Setting: England
Bold type indicates a book I've read.

1. Cast, in Order of Disappearance (1975)
2. So Much Blood (1976)
3. Star Trap (1977)
4. An Amateur Corpse (1978)
5. A Comedian Dies (1979)
6. The Dead Side of the Mike (1980)
7. Situation Tragedy (1981)
8. Murder Unprompted (1982)
9. Murder in the Title (1983)
10. Not Dead, Only Resting (1984)
11. Dead Giveaway (1985)
12. What Bloody Man is That? (1987)
13. A Series of Murders (1989)
14. Corporate Bodies (1991)
15. A Reconstructed Corpse (1993)
16. Sicken and So Die (1995)
17. Dead Room Farce (1998)
18. A Decent Interval (2013) 
19. The Cinderella Killer (2014)
20. A Deadly Habit (2018)

........

Len Deighton: Bernard Samson Novels

Main character: Bernard Samson, a British intelligence officer working for the Secret Intelligence Service (SIS).
Setting: England, Europe, Latin America
The novels were issued as three sets of trilogies, plus one "prequel."
Bold type indicates a book I've read.

Berlin Game (1983)
Mexico Set (1984)
London Match (1985)

Winter (1987)

Spy Hook (1988)
Spy Line (1989)
Spy Sinker (1990)

Faith (1994)
Hope (1995)
Charity (1996)

Len Deighton: The "Unnamed Hero" Series

Main Character: An anonymous secret agent (named "Harry Palmer" in the film adaptations)
Setting: England, Europe and USA
Bold type indicates a book I've read.

The IPCRESS File (1962)
Horse Under Water (1963)
Funeral in Berlin (1964)
Billion Dollar Brain (1966)
An Expensive Place to Die (1967)
Spy Story (1972)
Yesterday's Spy (1975)
Twinkle, Twinkle, Little Spy (1976), aka: Catch a Falling Spy

Dorothy L. Sayers: The Lord Peter Wimsey Mysteries

Main Character: Lord Peter Wimsey, aristocrat and amateur sleuth; some of the novels also feature mystery writer Harriet Vane
Setting: England
Bold type indicates a book I've read.

Whose Body? (1923)
Clouds of Witness (1926)
Unnatural Death (1927)
The Unpleasantness at the Bellona Club (1928)
Lord Peter Views the Body (1928) (short stories)
Strong Poison (1930)
Five Red Herrings (1931)
Have His Carcase (1932)
Hangman's Holiday (1933) (12 short stories, 4 including Lord Peter)
Murder Must Advertise (1933)
The Nine Tailors (1934)
Gaudy Night (1935)
Busman's Honeymoon (1937)
In the Teeth of the Evidence (1939) (18 short stories, 4 including Lord Peter)