Cowboy actor Jack Elam and Jack Holt were both prolific actors in the Western genre. Elam was known for his roles in films such as 'Once Upon a Time in the West' and 'Support Your Local Sheriff!', while Holt was known for his roles in films such as 'The Virginian' and 'The Return of Frank James'. Both actors were active in the 1940s and 1950s, and their work helped to shape the Western genre.