The Collaborative International Dictionary of English v.0.48:

Playgoer \Play"go`er\, n.
   One who frequents playhouses, or attends dramatic
   performances.
   [1913 Webster]

WordNet (r) 3.0 (2006):

playgoer
    n 1: someone who attends the theater [syn: playgoer,
         theatergoer, theatregoer]