Seth Harper

Seth "Snake-eyes" Harper was a gunfighter hired by Pa Clanton to help his sons kill Doc Holliday in October 1881. He heavily disliked his nickname. When he met the First Doctor, he thought the Doctor was Holliday and told the Clantons.

He encountered the real Holliday at the Last Chance Saloon and tried to kill him, but Holliday shot and killed Harper first. (TV: The Gunfighters)