What is the name of a person who impersonates someone else?

The name for a person who impersonates someone else is an impostor. An impostor is someone who pretends to be another person, usually for some kind of gain or advantage. They may impersonate someone to gain access to resources or information, or to deceive others into believing they are someone else. Impostors are often motivated by financial gain, but they may also be seeking recognition or trying to escape from their own identity. Impostors may use a variety of techniques to deceive their victims, such as using false documents, creating false social media profiles, or using voice-altering technology.