He was in a early to mid 70s made for TV movie, don't remember the title, about a group of people planing a heist. The line that still sticks with me for decades ( not sure if it was Hagman’s character who said it ) was “necessity's the mother.”
http://www.youtube.com/watch?v=QkU-oBjFvK0
He also had a small role in 1978’s “Superman: The Movie.”