Harry Alonzo Longabaugh (1867 November 7, 1908), better known as the Sundance Kid, was an outlaw and member of Butch Cassidy's Wild Bunch in the American Old West. He likely met Butch Cassidy (real name Robert Leroy Parker) after Cassidy was released from prison around 1896. The "Wild Bunch" gang performed the longest string of successful train and bank robberies in American history. Longabaugh fled the United States along with his consort Etta Place and Butch Cassidy to escape the dogged pursuit of the Pinkerton Detective Agency. The trio fled first to Argentina and then to Bolivia, where most historians believe Cassidy and Longabaugh were killed in a shootout in November 1908.

Robert LeRoy Parker (April 13, 1866 – November 7, 1908), better known as Butch Cassidy, was an American train and bank robber and the leader of a gang of criminal outlaws known as the "Wild Bunch" in the Old West.

Parker engaged in criminal activity for more than a decade at the end of the 19th century and the early 20th century, but the pressures of being pursued by law enforcement, notably the Pinkerton detective agency, forced him to flee the country. He fled with his accomplice Harry Longabaugh, known as the "Sundance Kid", and Longabaugh's girlfriend Etta Place. The trio traveled first to Argentina and then to Bolivia, where Parker and Longabaugh are believed to have been killed in a shootout with the Bolivian Army in November 1908; the exact circumstances of their fate continue to be disputed.

Parker's life and death have been extensively dramatized in film, television, and literature, and he remains one of the most well-known icons of the "Wild West" mythos in modern times.