Source : Webster's Revised Unabridged Dictionary (1913)

Protagonist \Pro*tag"o*nist\, n. [Gr. ?; prw^tos first + ? an
   actor, combatant, fr. ? a contest.]
   One who takes the leading part in a drama; hence, one who
   takes lead in some great scene, enterprise, conflict, or the
   like.

         Shakespeare, the protagonist on the great of modern
         poetry.                                  --De Quincey.

Source : WordNet®

protagonist
     n 1: a person who backs a politician or a team etc.; "all their
          supporters came out for the game"; "they are friends of
          the library" [syn: {supporter}, {champion}, {admirer}, {booster},
           {friend}]
     2: the principal character in a work of fiction [syn: {agonist}]