- Hamartia refers to a character's tragic flaw or error of judgment that ultimately leads to their downfall. It was first defined by Aristotle in Poetics to describe the mistake that causes a reversal of fortune for the protagonist. - Examples of hamartia discussed include Oedipus' pride and ignorance leading him to unknowingly kill his father and marry his mother, Hamlet's indecision causing his own destruction, and Frankenstein's hubris in creating life against nature's laws. - Hamartia is a key element of Greek tragedy that makes the characters' downfalls seem plausible and elicits pity from the audience rather than accusation, thus achieving catharsis.