The term “real” is problematic when speaking of drama, because the theatrical event is itself is a fictional construct; it could be said that nothing is “real” in a theatrical production.  But notwithstanding this ambiguity, the characters are invented, this time by an “author” not identified by Pirandello – this play is a dramatic discussion of how drama works.  The actors on stage are, of course, real, but the “characters” that the actors play are fictive inventions.  It can be argued that that makes them no less “real” – certainly Hamlet or Willie Loman or Stanley Kowalski could all lay claim to being “real”, in that thousands of people would be able to describe them in detail.  To ask about the “reality” of stage characters is itself an acknowledgement of their facticity. Perhaps the question should be rephrased:  Who is real to whom?  When sitting in the audience of the play's performance, the only "real" things are the actors saying Pirandello's lines.