A person who is completely ignored, as if he or she does not exist; specif., such a person officially ignored by his or her own government.
With his identity stolen he became an unperson unable to prove his existence to the government.
Origin of unperson
un- +"Ž person. From the synthetic language "newspeak" in George Orwell's novel Nineteen Eighty-Four (1949), where it refers to a person who has not only been executed but whose entire history has been erased.