Ferdinand Demara
Ferdinand Demara, or "the Great Imposter" as he came to be known, has a very impressive resume — the only thing it lacks is his real name. Under a series of stolen identities Demara worked as a civil engineer, a zoology graduate, a doctor of applied psychology, a monk on two separate occasions (Trappist and Benedictine), an assistant warden at a Texas prison, philosophy dean at a Pennsylvania college, a hospital orderly, a lawyer and a teacher — among other professions. In 1957, TIME Magazine described him as an "audacious, unschooled but amazingly intelligent pretender who always wanted to be a Somebody, and succeeded in being a whole raft of Somebody Elses."
Perhaps his most impressive impersonation came during the Korean War while impersonating a doctor on a Royal Canadian Navy Destroyer. When several Korean combat casualties were brought on board, the responsibility of saving their lives fell to Demara, the ship's sole "surgeon." Demara, who allegedly possessed a photographic memory and unusually high IQ, ducked into his quarters with a medical textbook and emerged to save the lives of every single man, including one who required major chest surgery. News of his heroics eventually unmasked him, and the resulting media attention ultimately prevented him from continuing his fraudulent lifestyle. Impersonation is considerably more difficult when the entire country knows your face.