As this is a relatively short story, it does not have a large number of characters, but rather features three central figures and some peripheral characters that form a background to the story but are not actively present in the narrative. The story is set in Cuba in a fishing village near Havana and all the characters in the story live in relative poverty and are dependent on the sea for their living. Much of the story takes place on the water.
Santiago: The "old man" of the title is an aging fisherman, Santiago, who has had the bad luck to have gone without a catch for 84 days despite his skill and experience. This is an economic disaster for him but also a personal one as his identity is very much wrapped up in his work and skill in fishing.
Manolin: This young boy is Santiago's former apprentice and despite his parents' disapproval, still is friends with Santiago, looks up to him as a mentor, and brings him food. Although Manolin's parents are not characters inside the main narrative they could be considered minor or background characters.
The Marlin: The large marlin with which Santiago struggles may not be human, but it is still the main antagonist of the story and an important presence.