The Collaborative International Dictionary of English v.0.48:

Interviewer \In"ter*view`er\, n.
   One who interviews; especially, one who obtains an interview
   with another for the purpose of eliciting his opinions or
   obtaining information for publication.
   [1913 Webster]

         It would have made him the prince of interviewers in
         these days.                              --Leslie
                                                  Stephen.
   [1913 Webster]

WordNet (r) 3.0 (2006):

interviewer
    n 1: a person who conducts an interview