Known to be difficult on the set, Hopkins flitted from studio to studio. After her early tenure at Paramount, she was under contract to independent producer Samuel Goldwyn during the mid-30s and by the end of the decade had moved to Warner Brothers, where a rivalry with Bette Davis manifested itself in both the plotline and the actual filming of the touching soaper, "The Old Maid" (1939). Her stardom began to decline toward the end of the decade after several films ("The Woman I Love" 1937, "Lady with Red Hair" 1940) fizzled at the box office. For a time Hopkins had been a critics' darling; as her films became more routine and she became increasingly disenchanted with her opportunities in Hollywood, some of her performances became more mannered. After another competitive reteaming with Davis in the enjoyably catty "Old Acquaintance" (1943), which put her fidgety qualities to good use, Hopkins returned to Broadway and stage tours and bid farewell to Hollywood for six years.
Hopkins began playing occasional film character parts at the end of the 40s. She was especially good in her first major supporting role in films, that of the solicitous, romantic aunt in a fine reunion film with Wyler, "The Heiress" (1949). Hopkins made intermittent appearances through the mid-60s, including one in Wyler's 1962 remake, "The Children's Hour" (playing the aunt of the character she had played 26 years earlier). She also did occasional TV work, perhaps most memorably in an outlandish yet highly effective and even moving Norma Desmond-type turn as an overage flapper still living in her youthful past in "Don't Open Till Doomsday", an especially memorable installment of the cult classic anthology series, "The Outer Limits".