Johnny Ringo was a gunfighter hired by Pa Clanton to help his sons kill Doc Holliday in October 1881. He was acquainted with Kate Fisher and believed her when she said Holliday had left Tombstone, Arizona for good with another woman, the First Doctor's companion Dodo Chaplet.
In Tombstone, he killed Charlie, the bartender of the Last Chance Saloon. During the gunfight at the O.K. Corral, he grabbed Dodo and threatened to kill her, but when he tried to kill Holliday, he was shot and killed instead. (TV: The Gunfighters)