n literature, an antagonist is a character or a group of characters which stand in opposition to the protagonist or the main character. The term antagonist comes from Greek word “antagonistēs” that means opponent, competitor or rival.
It is common to refer to an antagonist as a villain (the bad guy) against whom a hero (the good guy) fights in order to relieve himself or others. In some cases, an antagonist may exist within the protagonist that causes an inner conflict or a moral conflict inside his mind. This inner conflict is a major theme of many literary works e.g. Doctor Faustus by Christopher Marlowe, Hamlet by William Shakespeare, and A Portrait of an Artist as a Young Man by James Joyce etc. Generally, an antagonist appears as a foil to the main character embodying qualities that are in contrast with the qualities of the main character.