Sergeant William Preston is a fictional Canadian Mountie created by Fran Striker and George W. Trendle for the long-running radio serial Challenge of the Yukon.
The radio serial began in 1938 and continued through 1947, after which the series obtained a sponsor in "Quaker Oats", which led to its leap to television. The television program aired from 1947 through 1949 on ABC. The most prominent actors to play the role of Sergeant Preston were Paul Sutton and Brace Beemer. In 1955 the spin-off series Sergeant Preston of the Yukon began, starring Richard Simmons. Running for 78 weekly episodes, what was interesting was that the series had only two characters who appeared in all 78 episodes, one of which was a dog, with no other single character appearing in more than a total of 20 episodes, and with most appearing in less than five.
Sergeant William Preston is a heroic police officer, who is tasked with policing the wilds of the Canadian frontier alone, accompanied only by his dog "Yukon King" and his horse, "Rex". Each episode has him battling a new crisis, whether it be tracking down a murderer, a gang of thieves, or claim jumping miners. His dog, "Yukon King", is at times a central character, with several episodes revolving around an event centering on him. During the course of the series, Preston successfully puts down a rebellion, and captures assassins.