This tragic flaw is very clearly apparent in Okonkwo, the protagonist of Achebe's Things Fall Apart. He is very strong and very masculine according to the expectations of his people, and this both helps him to win success amongst his people despite the shame of his family background -- his father was not well respected in the community -- and causes him to be banished from the villages. This banishment somewhat ironically -- though in a perfect twist for a tragic plot -- weakens the villages and enables the white newcomers' ways to dominate the society, which ultimately leads to Okonkwo's "weak" death at his own hands. The beginning of the change can be seen when Okonkwo convinces himself to take part in the ritual slaying of a kidnapped boy from another village, despite warnings that he should avoid participation: "When did you become a shivering...
This clearly shows the transition form Okonkwo's consistent strength turning from a benefit to him and his society to a detriment, leading to his downfall.
Not all works dramatic or tragic in nature follow the formula laid out by Aristotle in his Poetics, of course, and Achebe takes many departures form the prescribed "best tragedy" in his novel, Things Fall Apart. At the same time, the basic structure of tragedy and tragic characters as Aristotle describes it can be seen echoed in many stories, regardless of whether or not such elements were consciously designed according to his rules. Perhaps this simply reflects the universality of human responses to dramatic events and well drawn characters.
