1. The main character in a drama or other literary work.
2. In ancient Greek drama, the first actor to engage in dialogue with the chorus, in later dramas playing the main character and some minor characters as well.
3. 1. A leading or principal figure.
   2. The leader of a cause; a champion.
4. Usage Problem A proponent; an advocate.

Usage Note: The protagonist of a Greek drama was its leading actor; therefore, there could be only one in a play. The question for speakers of modern English is whether a drama can have more than one protagonist. When members of the Usage Panel were asked "How many protagonists are there in Othello?" the great majority answered "One" and offered substitutes such as antagonist, villain, principal, and deuteragonist to describe Desdemona and Iago. Nevertheless, the word has been used in the plural to mean "important actors" or "principal characters" since at least 1671 when John Dryden wrote "Tis charg'd upon me that I make debauch'd persons ... my protagonists, or the chief persons of the drama." Some writers may prefer to confine their use of protagonist to refer to a single actor or chief participant, but it is pointless to insist that the broader use is wrong. · The use of protagonist to refer to a proponent has become common only in the 20th century and may have been influenced by a misconception that the first syllable of the word represents the prefix pro-, "favoring." In sentences such as He was an early protagonist of nuclear power, this use is likely to strike many readers as an error and can usually be replaced by advocate or proponent.