生于纽约州罗彻斯特，原名小罗伯特．福斯特。相继在海德尔堡学院、艾尔弗雷德大学及罗彻大学学习。早期从事戏剧演出，60年代下半期开始演出影片，至2001年主演或参与演出近80部影片。主要有《穿行的月亮》、《残梦》、《敢死队》、《唐死了》、《雪山大崩溃》、《警惕》等。
Robert Cornthwaite first got hooked on acting at age 13, when he was forced to play a one-line part in an eighth grade play. He did his first work with professionals five years later, in a 1935 production of "Twelfth Night" on the Reed College campus in Portland. He worked in radio in Southern California before he was inducted into the Air Force during World War II (a four-year hitch). Returning to Hollywood after the War, Cornthwaite went back into radio and then began working as a character man in features and TV. He prefers theater, which he feels is "far more liberating for the actor" than film.
