Tim Matheson played Jim Horn in the Virginian in the very early 1970s, that's when I first saw him anyway, then he did the Coke advert, with the Bobby Goldsboro song 'Hello Summertime' which had altered lyrics for Coca Cola, Then Tim did dozens of other TV work and still does. I have him on my facebook BTW.
Of course Kurt Russell had always been in TV but went on to do some damn good movies, Escape from New York and Executive Decision being my faves of his, he married Goldie Hawn years ago.