noun (n)

• someone who (fraudulently) assumes the appearance of another(noun.person)

  Synonym:
  impersonator
  

  source: wordnet30
• someone who copies the words or behavior of another(noun.person)

  Synonym:
  ape, aper, copycat, emulator
  

  source: wordnet30
• One who imitates.(noun)

  source: webster1913