In fiction and folklore, a doppelgänger (German "double walker") is a paranormal double of a living person, typically representing evil or misfortune. In the vernacular, the word has come to refer to any double or look-alike of a person.
The word also is used to describe the sensation of having glimpsed oneself in peripheral vision, in a position where there is no chance that it could have been a reflection. Doppelgängers often are perceived as a sinister form of bilocation and are regarded by some to be harbingers of bad luck. In some traditions, a doppelgänger seen by a person's friends or relatives portends illness or danger, while seeing one's own doppelgänger is an omen of death.