Chekov as William Claiborne
William "Billy" Claiborne was a 19th century Human gunman who was involved in the shootout at the OK Corral, in Tombstone, Arizona, on October 26th, 1881. Claiborne was one of two survivors on the losing side of the duel.
In 2268, Pavel Chekov was identified as Billy Claiborne in a bizzare recreation of the duel created by the Melkot. (TOS: "Spectre of the Gun")