Okonkwo is the protagonist of Nigerian writer Chinua Achebe's 1958 novel, Things Fall Apart. The question is often asked if Okonkwo, a member of the Igbo tribe, is a tragic hero, and there are really two answers.
If we look at it from a Greek or Elizabethan perspective, then no, Okonkwo does not fit the definition of a classic tragic hero. The Greeks, in particular, had a narrow understanding, as laid out in Aristotle's Poetics, of what a tragic hero is. What Oknokwo does share with heroes like Oedipus or Hamlet is that he is representative of his community, elevated within his community (he's a famous wrestler), and has a tragic flaw which brings about his fall. Pride or hubris is a quality many tragic protagonists share, and Okonkwo is bursting with pride. He's a successful and prominent member of his tribe, but he's also angry, violent, arrogant, and abusive of his wives and children. He's eventually expelled from his community for breaking the tribe's rules.
Again, from a classical perspective, the book does not qualify as a tragedy. But I think there's a strong case to make that it is a contemporary tragedy. The tragedy works on two levels. Okonkwo's arc is similar to that of other heroes, as he goes from high status to expulsion and exile to death by suicide. Whether the reader experiences the catharsis expected of a tragedy is, of course, subjective.
On another level, Things Fall Apart is the tragedy of an entire people as, in the second part of the book, white Westerners arrive and, with them, Christianity, capitalism, and colonialism. The Igbo will have their culture destroyed, their lands pillaged, and their religion mocked, as will much of the continent. Colonialism is a tragedy for all those who experienced it, all the more so because it was presented by Europeans as a positive force.