Impostor

(n.) One who imposes upon others; a person who assumes a character or title not his own, for the purpose of deception; a pretender.

Thesaurus Entries

ape, beguiler, blagueur, bluff, bluffer, charlatan, cheat, clinquant, con man, confidence man, conformist, copier, copycat, copyist, counterfeit, counterfeiter, cuckoo, deceiver, dissembler, dissimulator, dummy, echo, echoer, echoist, fake, fakement, faker, flimflam man, forger, forgery, fourflusher, frame-up, fraud, hoax, humbug, hypocrite, imitation, imitator, impersonator, imposter, junk, malingerer, mime, mimer, mimic, mimicker, misleader, mock, mocker, mockingbird, monkey, mountebank, parrot, paste, pettifogger, phony, pinchbeck, plagiarist, poll-parrot, polly, polly-parrot, poser, poseur, pretender, put-on, put-up job, quack, quacksalver, quackster, ringer, rip-off, saltimbanco, sham, shammer, shark, sheep, shoddy, shyster, simulacrum, simulator, swindle, swindler, tinsel, trickster, whited sepulcher