In 1895 French writer Georges Polti drew up a list of every dramatic situation that might arise in a story or performance, based on an earlier list drawn up by Venetian playwright Carlo Gozzi. They number only 36 — Polti listed the elements necessary for each:

1. Supplication (“a Persecutor, a Suppliant and a Power in authority, whose decision is doubtful”)
2. Deliverance (“an Unfortunate, a Threatener, a Rescuer”)
3. Crime Pursued by Vengeance (“an Avenger and a Criminal”)
4. Vengeance Taken for Kindred Upon Kindred (“Avenging Kinsman, Guilty Kinsman, Remembrance of the Victim, a Relative of Both”)
5. Pursuit (“Punishment and Fugitive”)
6. Disaster (“a Vanquished Power, a Victorious Enemy or a Messenger”)
7. Falling Prey to Cruelty or Misfortune (“an Unfortunate, a Master or a Misfortune”)
8. Revolt (“Tyrant and Conspirator”)
9. Daring Enterprise (“A Bold Leader, an Object, an Adversary”)
10. Abduction (“The Abductor, the Abducted; the Guardian”)
11. The Enigma (“Interrogator, Seeker and Problem”)
12. Obtaining (“A Solicitor and an Adversary Who Is Refusing, or an Arbitrator and Opposing Parties”)
13. Enmity of Kinsmen (“a Malevolent Kinsman; a Hated or Reciprocally Hating Kinsman”)
14. Rivalry of Kinsmen (“The Preferred Kinsman; the Rejected Kinsman; the Object”)
15. Murderous Adultery (“Two Adulterers; a Betrayed Husband or Wife”)
16. Madness (“Madman and Victim”)
17. Fatal Imprudence (“The Imprudent; the Victim or the Object Lost”)
18. Involuntary Crimes of Love (“The Lover; the Beloved; the Revealer”)
19. Slaying of a Kinsman Unrecognized (“The Slayer; the Unrecognized Victim”)
20. Self-Sacrifice for an Ideal (“The Hero; the Ideal; the ‘Creditor’ or the Person or Thing Sacrificed”)
21. Self-Sacrifice for Kindred (“The Hero; the Kinsman; the ‘Creditor’ or the Person or Thing Sacrificed”)
22. All Sacrificed for a Passion (“The Lover; the Object of the Fatal Passion; the Person or Thing Sacrificed”)
23. Necessity of Sacrificing Loved Ones (“The Hero; the Beloved Victim; the Necessity for the Sacrifice”)
24. Rivalry of Superior and Inferior (“The Superior Rival; the Inferior Rival; the Object”)
25. Adultery (“A Deceived Husband or Wife; Two Adulterers”)
26. Crimes of Love (“The Lover; the Beloved”)
27. Discovery of the Dishonor of a Loved One (“The Discoverer; the Guilty One”)
28. Obstacles to Love (“Two Lovers; an Obstacle”)
29. An Enemy Loved (“The Beloved Enemy; the Lover; the Hater”)
30. Ambition (“An Ambitious Person; a Thing Coveted; an Adversary”)
31. Conflict With a God (“A Mortal; an Immortal”)
32. Mistaken Jealousy (“The Jealous One; The Object of Whose Possession He Is Jealous; the Supposed Accomplice; the Cause or the Author of the Mistake”)
33. Erroneous Judgment (“The Mistaken One; the Victim of the Mistake; the Cause or Author of the Mistake; the Guilty Person”)
34. Remorse (“The Culprit; the Victim or the Sin; the Interrogator”)
35. Recovery of a Lost One (“The Seeker; the One Found”)
36. Loss of Loved Ones (“A Kinsman Slain; a Kinsman Spectator; an Executioner”)

Each situation has its variations; for example, The Count of Monte Cristo is a Revenge for a False Accusation, a variation on the Crime Pursued by Vengeance; and Great Expectations is a Life Sacrificed for the Happiness of a Relative or Loved One, a variation on Self-Sacrifice for Kindred.

The whole book is here.