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.

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).