OK, here's my two cents to add to the mix.

Lucas McCain rode "Razor" and Mark McCain rode "Blueboy" on "The Rifleman".

"Paint" and "Chochise" were ridden by Little Joe Cartright on Bonanza and "Chub", "Paiute" and "Ginger" were ridden by Hoss. Adam rode both "Beauty" and "Sport" and Ben rode both "Buck" and "Waggoner".

"Hi Ho Silver"...the Lone Ranger

"Topper"...Hopalong Cassidy

"Buttermilk" was Dale Evans horse

I'll leave a few for the rest of you to figure out!