Noun
tragic flaw (plural tragic flaws)
(chiefly literary criticism) A personality trait or other characteristic of a real or fictional individual which is immoral, destructive, or otherwise faulty and which leads to the ruin or profound suffering of that individual.
As conventional in Greek tragedies, Oedipus is portrayed as a heroic protagonist, led to his downfall by his tragic flaw, ‘hubris’, error of judgement, ‘hamartia’, and most importantly, fate. Source: Internet
Mayor Daley is a brilliant administrator but he has a tragic flaw. Source: Internet