The juvenile lead was successively played by James Ellison, Russell Hayden, George Reeves, Rand Brooks, and Jimmy Rogers. George Hayes (later to become known as "Gabby" Hayes) originally played Cassidy's grizzled sidekick, Windy Halliday. After Hayes left the series because of a salary dispute with producer Harry Sherman, he was replaced by the comedian Britt Wood as Speedy McGinnis and finally by the veteran movie comedian Andy Clyde as California Carlson. Clyde, the most durable of the sidekicks, remained with the series until it ended. A few actors of future prominence appeared in Cassidy films, notably Robert Mitchum, who appeared in seven films at the beginning of his career.