Darius McCollum
Darius McCollum isn't the most efficient imposter on this list, but he's definitely the most persistent. McCollum has been arrested 26 times for impersonating various transit employees, including famously driving a New York City subway train while only 15 years old. Suffering from Asperger syndrome, an autism spectrum disorder, McCollum has been obsessed with trains since he was a child, having memorized the city's subway system by age five.
Born and raised in New York and confined there by parole restrictions for the majority of his adult life, McCollum is unable to escape the object of his obsession. He has become a minor cult figure, inspiring plays, documentaries and songs. Despite perhaps knowing more about trains than any employee, the New York City Transit Authority has refused to hire him because of his past convictions, and with no treatment for the disorder that drives him back to the tracks, McCollum's 26th arrest might not be his last.