impostor

noun

1. Someone who attempts to deceive by using an assumed name or identity.

   “"It were dishonour in me to yield. I will not play the part of an impostor, whom my uncle must despise even while he screens. No; these estates are his right: let him take them; I will not buy them with his daughter's hand."”

   “Then again these figures take no account of the thousands of beggars who travel free in India. Many of these are religious "Sadhus", dressed often in nothing but a loin-cloth, or even less, and their bodies smeared with ashes. A large number of these men are nothing but impostors, but the Hindu railway staff usually are afraid to interfere with them.”

   ““I said he had a criminal face.” “He can't help his face.” “He can help being a crook and an impostor. Calls himself a butler, does he? The police could shake that story. He's no more a butler than I am.””

2. A sprite or animation integrated into a three-dimensional scene to look like part of the 3D world.
3. A term referenced in an unusual grammatical person.

   “Interestingly, Wang shows that Chinese allows the appearance of an indexical pronoun alongside the imposter, as in (31).”

   “One possibility is that mothers of HR [higher-risk] infants frequently use non-pronoun forms in place of pronouns, as in the impostor uses noted above.”