Possibly:
Diablo - Black & white pinto mare ridden by Duncan Renaldo when he played the Cisco Kid, a Mexican "Robin Hood of the Old West" on the western adventure THE CISCO KID/SYN/1950-56. In the original O. Henry story The Caballero's Way (1907), (the inspiration for a series) Cisco's horse was an unnamed speckled roan. In the movies (starring Cesar Romero, Gilbert Roland, Warren Daxter, and Duncan Renaldo) and the TV series, the horse was called Diablo. When Diablo retired, he was stabled at the Santa Barbara home of Duncan Renaldo. Cisco's sidekick, Pancho (Leo Carrillo) rode a horse named Loco.