The Apache Kid was Aloysius Kare [Apache name of Dazii], a scout who lived a double life as the son of Apache chief Red Hawk; his horse was Nightwind.
The Black Rider was Dr. Matt Masters, who would don a mask to seek justice. His horse Satan also had a double identity, as Masters' horse Ichabod. Only Bobby Lathrop knew his secret. Made part of the Marvel Universe in Avengers Forever#5.
The Ghost Rider was Carter Slade, a schoolteacher named by the Comanche Flaming Star as a champion of "the sky-spirit". Only Jaime Jacobs knew his true identity; his horse was Banshee. Made part of the Marvel Universe in Avengers#141.
Kid Colt was Blaine Colt; his horse was Steel. Made part of the Marvel Universe in Avengers#141.
Matt Slade was a gunfighter secretly employed by for Governor Anson Clinton; his horse was Eagle.
The Outlaw Kid was Lance Temple, meek worker on his blind father's ranch; his horse was Thunder [Blazer in late 60's appearances].
The Rawhide Kid was Johnny Bart, originally a town defender with his sidekick Randy, but usually an outlaw on the run; his horse was Nightwind. Made part of the Marvel Universe in Avengers#141.
The Ringo Kid was the son of American Cory Rand, and a Cheyenne [in some stories, Comanche] woman; pursued by the law, he would battle law-breakers alongside his father, and Dull Knife, his blood brother; his horse was the Arabian stallion Arab. Made part of the Marvel Universe in Avengers#141.
The Two-Gun Kid from Two-Gun Kid#60-up was lawyer Matt Hawk; his horse was Thunder. Only town blacksmith Boom-Boom Brown knew his true identity. Made part of the Marvel Universe in Avengers#141. The Two-Gun Kid from Two-Gun Kid#1-59 was Clay Harder, a singing cowboy; his horse was Cyclone. Two-Gun Kid#60 established him as a fictional hero.