In no particular order John Wayne rode Bo (or Beau), Dollor, Dollar, Cochise, Duke, Banner, Steel, Alamo, and Starlight
The two he rode for the longest period of time seem to be Banner (14 years) and DollarChat with our AI personalities
Mr. Wayne had a series of horses that were his personally. The horse he owned until shortly before his death was a registered Quarter Horse named Dollar. When Wayne got the word about his terminal cancer he sold the horse for $15,000.
In his later career John Waynes' horse of choice was a chestnut quarter horse named Dollor. Dollor appeared in "True Grit", "The Undefeated", "Rio Lobo", "Chisum", and "The Shootist"
Where have all the cowboys gone, Save a horse ride a cowboy.
John Wayne had a film career that lasted more than 50 years. It would be impossible for him the use the same horse but his later movies he did use his own horse, a 16HH chestnut Quarter Horse who went by the name Dollar.
Well, honey, John Wayne rode a horse named Duke in the movie "The War Wagon." And no, Duke wasn't just a random horse, it was actually John Wayne's own horse. So, there you have it, Duke the horse was John Wayne's trusty steed in that classic western flick.
FAMILY FEUD ANSWERS: Ride a horse Shoot Act Fight
I think in Cahill:US Marshal Wayne was forced to ride a mule (donkey/horse cross) due to lack of a better mount. There may have been other movies where he rode a mule but I can't remember.