During the 1960s, Brown had a variety of roles in films, including Henri Philipot in The Comedians (1967), Theon Gibson in Dayton's Devils (1968), and Dr. Willard in Bullitt (1968). His 1970s films included Colossus: The Forbin Project (1970), The Man (1972), and Wild in the Sky (1972), co-starring Brandon De Wilde, as anti-war, anti-establishment guerrillas, who devise a scheme to destroy Fort Knox with an atomic bomb.