Antihero

An antihero is "a literary term that can be understood as standing in opposition to the traditional hero": not the high-status, publicly admired figure of classical storytelling, but typically an outsider, sometimes a criminal, pushed into the hero's role, whose actions are "both morally righteous and at the same time questionable." The term has been used since 1714; its family includes the Byronic hero, the picaresque rogue and the modern TV antihero, and its canonical examples run from Don Quixote to Dostoevsky's underground man and Huckleberry Finn.

For novelists the antihero is a promise about character arcs: a flawed lead still has to earn reader investment, which happens when the flaws cost something and change the character. The term is the useful opposite of the Mary Sue, criticized for having no flaws at all, and web fiction's darker genres run on antiheroic leads.