Hannah Emily Upp suffers from dissociative fugue, "a rare form of amnesia that causes people to forget their identity, suddenly and without warning, and can last from a few hours to years", which caused her to disappear from her usual life for three weeks until she was found floating, alive, in New York Harbor.
Its most famous sufferer is the fictional Jason Bourne, the secret agent made flesh on film by Matt Damon. The Bourne character takes his name from Ansel Bourne, a Rhode Island preacher who suffered the earliest recorded case of the condition when he was en route to Providence in 1887. The preacher continued to Norristown, Pa., where he opened a store and lived with another family, until one day he "woke up."