Rex - Black horse on the northwest adventure SERGEANT PRESTON OF THE YUKON/CBS/1955-58.

Rex (originally called "Blackie") belonged to Sergeant Preston (Richard Simmons), a member of the Royal Canadian Mounted Police who patrolled the Yukon area of Canada in the Gold Rush years of the 1890s.

The original horse used for the series was a show horse purchased by George Trendle, the producer for $17,000. Unfortunately, it was too jittery and not suited for rugged outdoor work. Eventually the horse was replaced by another horse better suited for filming in the wilderness.

According to "The Encyclopedia of TV Pets," when Richard Simmons broke his wrist after the horse fell backwards, he said "You're gonna have to get a new guy to play the part or you're gonna have to get a new horse." Soon after, the horse was replaced by a young American saddle bred horse that remained for the rest of the series. Glenn Randall was the show's horse trainer.

Series dog trainer Beverly Allen reported that Rex the horse and King,  Preston's canine sidekick were great pals. "When we first put them together, they didn't do anything buy play."

TRIVIA NOTE: Rex was also the name of the black gelding horse ridden by William Colton (Lloyd Bridges) former Union cavalry captain who wandered the west in the days after the Civil War on the western adventure THE LONER/CBS/1965-66. His registered name was Montrose Sea and he was owned by Glenn Randall.

There was also a Rex called "King of the Wild Horses" who appeared in several movie serials including The Law of the Wild (1934) and The Adventures of Rex and Rinty (1935).