Source : Webster's Revised Unabridged Dictionary (1913)

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

   2. (Zo["o]l.) An animal which imitates something else, in
      form or habits.

Source : WordNet®

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