The term has several possible meanings: (1) the principle of retributive justice (sometimes referred to as "poetic justice") by which good characters are rewarded and bad characters are appropriately punished; (2) the agent or deliverer of such justice, who exacts vengeance and meets out rewards, as, for example the Duke in Shakespeare's *Measure for Measure*. In classical mythology, Nemesis was the patron goddess of vengeance; the expression often denotes a character in a drama who brings about another's downfall, so that Hamlet may be said to be Claudius's nemesis in Shakespeare's tragedy.