Someone who (fraudulently) assumes the appearance of another.

synonym: impersonator.

Dutch: imitator

Someone who copies the words or behavior of another.

synonyms: ape, aper, copycat, emulator.

Roget 19: imitation; copying etc. v.; transcription; repetition, duplication, reduplication; quotation; reproduction; mimeograph, xerox, facsimile; reprint, offprint.    mockery, mimicry; simulation, impersonation, personation; representation etc. 554; semblance; copy etc. 21; assimilation.    paraphrase, parody, take-off, lampoon, caricature etc. 21.    plagiarism; forgery, counterfeit etc. (falsehood) 544; celluloid.    imitator, echo, cuckoo^†, parrot, ape, monkey, mocking bird, mime; copyist, copycat; plagiarist, pirate.    ... show more

Dutch: na aper, naäper, na-aper, nabootser, namaker, imitator
Polish: imitator, naśladowca, odtwórca