An Impostor (or Imposter) is a person who pretends to be somebody else.
Most impostors try to gain financial or social advantages. Pretenders for various thrones used to be common. Numerous men claimed they were Dauphin, heir to the French throne who disappeared during the French Revolution. There were at least two false Dimitris who were serious pretenders for the throne of Russia.
Very daring impostors may pretend to be someone else who really exists although fast news media has made this rather difficult in these days. Usually they just misrepresent their financial, educational or social status, family background and in some cases, their gender.
Impostors are usually aware of not being who they say they are; they are not the proverbial lunatics who think they are Napoleon. However there are borderline cases who may have ended up believing their own tall tales.
People may make false claims about their past or background—that they can sing, for example—without being full-blown impostors; non-existent military service seems common. Only if a significant part of their past is fabricated—like that of George Dupre who claimed to have been an SOE agent in World War II—they approach the admittedly hazy border.
Many temporary impostors are criminals who maintain the façade for a time of a caper to defraud their victims (like Wilhelm Voigt). Others, like US prankster Joey Skaggs, do it as a prank or to make a point of some kind. The latter usually reveal the truth sooner or later. Some, like John Howard Griffin, have adopted other identity for purposes of research, investigation or experiment.
Note that although impostors usually misrepresent their background, their intentions may not be criminal as such. They may wish to start anew with a new identity or "go native"; i.e. adopt identity and customs of other people. Sometimes women have masqueraded as men to obtain privileges only men can have or work in male-dominated professions (see James Barry). Some of them have fought as men at least in Napoleonic Wars and American Civil War.
Sometimes an organization (or even individual) who has been fooled keeps quiet to avoid the embarrassment and therefore allows the impostor try the same thing elsewhere.
Of course, the most successful impostors are those whose duplicity is never revealed so that we know nothing about them.
People who tried to begin anew
- Martin Hewitt, who became a university professor without real credentials
- Brian MacKinnon, who went back to being a teenager in order to re-enter medical school
People who "went native"
Women who lived as men
Many women in history, who may not have been transgendered, have presented themselves as men in order to advance in typically male-dominated fields.
- Sarah Burton: Impostors - Six kinds of liar
Impostor (1953) is also the name of a short story by Philip K. Dick, and of a movie (2002) based on the short story.