He got his big break playing hapless fugitive Clovis Poplin in The Sugarland Express, the feature film debut of Steven Spielberg. After this, he garnered major roles in dark dramas such as The Day of the Locust and Looking for Mr. Goodbar, as well as the big-budget disaster film The Hindenburg. Atherton also starred as Cowboy Jim Lloyd in the 1978 miniseries Centennial, based on the novel by James Michener. In 1984, Atherton appeared in the comedy Ghostbusters as the EPA agent Walter Peck. In 1985, Martha Coolidge chose Atherton to play Professor Jerry Hathaway in the teen comedy Real Genius. In 1988, Atherton played reporter Richard "Dick" Thornburg in the blockbuster action film Die Hard, and reprised the role in its 1990 sequel Die Hard 2.