Today we look at a word that, to paraphrase Marlon Brando, "coulda been a contender." The term is agonist, meaning "one that is engaged in a struggle," such as the leading character in a literary work. The "coulda been a contender" quotation reflects the fact that agonist is far less common a term than its kin protagonist.

Fans of John Milton are familiar with that 17th-century poet's 1671 work, Samson Agonistes, in which the blinded and disgraced one-time hero—the protagonist and the agonist—overcomes his misery and renews his spiritual commitment to God.

The Greek agonistes, meaning "combatant or actor," inspired both agonist (in the early 1600s) and protagonist (some fifty years later). While agonist is used to refer to "someone engaged in a struggle" or to "someone beset by intellectual or spiritual conflicts," protagonist emphasizes the significance of the actor himself (or herself): the "proto-" in protagonist means "first."

Pairing "anti-," meaning "against," with agonist yields our third and oldest term of the trio: antagonist. In literature, an antagonist is "the principal opponent or foil of the main character"; the term honors its Greek ancestry when it is used in its original sense "adversary or opponent."