Hopalong Cassidy was already an established brand by the early 1950s, having appeared in books by Clarence Mulford. They were optioned for motion pictures starring Bill Boyd as Hoppy, beginning in 1936. The Hoppy of the movies was very different from the illiterate, tobacco-chewing cowhand described by Mulford, so the author took his money and in disgust at what had been done to his character washed his hands of the whole franchise.
By the end of the forties Boyd had mortgaged everything he owned to buy the rights to Hopalong Cassidy, which included 66 movies, plus the television rights, and then he created an empire. This 1950 Life article describes what he did and how he did it. I wouldn't doubt that Walt Disney, who was already a master of publicity and licensing, took careful note of Boyd’s success and duplicated it a few years later with Davy Crockett.
Boyd died in 1972, and by then the real success of Hopalong Cassidy was well behind him, but nowadays those licensed products that when new cost kids 49¢ or a buck are now high-priced collectibles.