No. Hayes Cooper and his diary was an invention of the "Walker" writers. Although his name is similar to famous Ranger Captain John Coffee Hays, there is no connection.
The adventures of the masked Texas Ranger began in the 1915 book by Zane Grey, The Lone Star Ranger. The writers of the 1950s radio and TV series gave the character a well-developed backstory involving an ambush, a near-death escape, an American Indian partner, a wounded white horse, and an incognito quest to right wrongs across the American plains.
This Ranger’s stories were made-up, but they sure made for some memorable TV. As per T.H. Fehrenbach, they were one of the most colorful, efficient, and deadly band of irregular partisans on the side of law and order the world has seen.
Learn more about Texas Rangers at Thestoryoftexas.com.
Want to become a Texas Ranger? Check out some special requirements required for entry employment at Txdps.state.tx.us.