Fuller's first small role was as an extra in the 1952 film "Above and Beyond". This part led to much extra work on many projects, one of which was in "I Love Melvin." In 1953, he again had another minor part in "Gentlemen Prefer Blondes," which starred Marilyn Monroe. Fuller's career then went on hold for service in the United States Army. He served a tour of duty in Korea and returned to the United States in 1955. Though he had been considering giving up acting, Fuller, at the suggestion of his best friend, Chuck Courtney, attended Richard Boone's acting classes. Boone suggested that Fuller study under the tutelage of Sanford Meisner at New York City's Neighborhood Playhouse. Fuller's first speaking role was in "Friendly Persuasion" in 1956, where he worked with his future "Laramie" co-star John Smith and another close friend, Doug McClure.