Complex sentence: The juvenile lead was successively played by James Ellison, Russell Hayden, George Reeves, Rand Brooks and (later to become known as "Gabby" Hayes) originally played Cassidy's grizzled sidekick, Windy Halliday.
Split into simpler sentences: The juvenile lead was successively played by James Ellison, Russell Hayden, George Reeves, and Rand Brooks. George Hayes (later to become known as "Gabby" Hayes) originally played Cassidy's grizzled sidekick, Windy Halliday.