impostor

One who engages in deception under an assumed name or identity.

One who imposes on others; a person who practises deception, usually under a false guise or an assumed character.

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

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

a person who makes deceitful pretenses