Robert Fields has always been a far busier stage actor than a film performer, but this hasn't prevented him from appearing in a number of notable theatrical and made-for-television features since the 1950s. His first break came in 1957 when he was chosen for the role of Tony, one of the "teenagers" (though he was well into his twenties at the time) in The Blob, an independently produced sci-fi/horror film being shot in Pennsylvania. Fields was a friend of Steve McQueen, who starred in the film, and their scenes together had a dynamism in the acting that made them one of the most effective parts of the movie, which has become regarded as a classic of the sci-fi genre. Fields was absent from films for the next decade but did a considerable amount of theater work, including Marat/Sade. He next appeared on screen in The Incident, a tense drama about a group of people victimized by a pair of thugs on a New York City subway. Following the hit They Shoot Horses, Don't They?, the next two films in which Fields worked, Cover Me Babe and The Sporting Club, fared so poorly among critics and at the box office that they virtually disappeared without a trace. But in 1973, he played an assistant district attorney in The Marcus-Nelson Murders, which was one of the most watched made-for-television features of the decade. Fields also played major roles in such films as the international production Vertigo En Manhattan during the early 1980s and appeared in Bob Fosse's Star 80, but has had his most visible big-screen success to date with his performance as the male lead in Anna, directed by Yurek Bogayevicz and starring Sally Kirkland.