Hardin began acting on television in the 1950s, mostly in character roles. He amassed over a hundred appearances by the early 1990s, in addition to more than seventy-five theatrical credits by the early 1960s. His television appearances include roles in the 1976 western series Sara, World War III, Star Trek: The Next Generation, Star Trek: Voyager, Sliders, and Lois & Clark: The New Adventures of Superman. Hardin appeared in such films as Thunder Road (1958), Our Time (1974),The Rockford Files (1977), Chilly Scenes of Winter (1979), 1941 (1979), Reds (1981), Missing (1982), Tempest (1982), Honkytonk Man (1982), Cujo (1983), Mass Appeal (1984), Warning Sign (1985), Big Trouble in Little China (1986), Let's Get Harry (1986), Wanted: Dead or Alive (1987), Little Nikita (1988), The Milagro Beanfield War (1988), Blaze (1989), The Hot Spot (1990), The Firm (1993).