Cowboy

A cowboy was an individual that tended cattle. They had their origins in the 19th century American West.

When they visited Tombstone in October 1881, Steven and Dodo dressed as fancy cowboys. (TV: The Gunfighters)

Lassos were used by cowboys to catch cows. (COMIC: Ripper's Curse)

Although he was from 1746, Jamie McCrimmon knew what a cowboy was. (AUDIO: House of Cards)

In 1963, Malcolm had a toy gonk, whom he named Cowboy Gonk. (PROSE: Time and Relative)

Behind the scenes
According to Are You Observant?, a game from The Doctor Who Fun Book, there existed Mondasian cowboys who dwelt in the Black Hills of Mondas.