A Nemesis is an opponent or enemy who is created by the actions of a hero (or another villain) within a story or legend. The name is derived from the Greek goddess of vengeance who would punish people who committed hubris. A good example of a nemesis would be Grendel's Mother, who fought Beowulf after the hero killed her son.

A nemesis often overlaps with Wrathful and Vengeful. By very definition, it is a specific subset of an Archenemy and the opposite of a Provoker. It can also overlap with one of the latter two to make an Arch-nemesis. An example of said villain is the Joker from the Burtonverse who murdered Bruce Wayne' parents when he was Jack Napier, causing the boy to become Batman but was later accidentally touched by a bullet deviated by Batman who caused him to fall into a cistern of chemicals products and to become the Joker.