mimicker

from WordNet (r) 3.0 (2006)

mimicker
    n 1: someone who mimics (especially an actor or actress) [syn:
         {mimic}, {mimicker}]

from The Collaborative International Dictionary of English v.0.48

Mimicker \Mim"ick*er\, n.
   1. One who mimics; a mimic.
      [1913 Webster]

   2. (Zool.) An animal which imitates something else, in form
      or habits.
      [1913 Webster]