Hopalong Cassidy was a western adventure drama broadcast from 1948 to 1952. The story featured the cowboy, detective hero Hopalong Cassidy. The character was created in 1904 by Clarence E. Mulford for his pulp short stories. Beginning in 1935, the hero, played by Hollywood star William Boyd, emerged triumphantly on the air, TV, and in films. Andy Clyde and later George McMichael played the sidekick California Carlson. By 1950, William Boyd was at the peak of his career and his character Cassidy a national hero. With great sound effects and memorable theme music, the series was especially popular among millions of American children, a phenomenon puzzling many a historian.