The term 'Jack of Old Westerns' refers to two iconic actors from the golden age of western films, Jack Elam and Tim Holt. Jack Elam was an American actor known for his roles in western films such as 'Support Your Local Sheriff!' and 'Once Upon a Time in the West'. Tim Holt was an American actor who starred in many western films, including 'The Treasure of the Sierra Madre' and 'Red River'. Both actors were renowned for their performances in western films and are remembered fondly by fans of the genre.