Brennan had long displayed a keen sense of camp by this point in her career, and in "At Long Last Love" (1975) showed an affinity for the glories of classical Hollywood's tough but good-hearted working women of 30s backstage musicals and 40s film noirs. Her greatest success in features came in the late 70s as tough but neurotic old-style dames in comedies including "Murder by Death" (1976) and "The Cheap Detective" (1978). Her work as a tough Army captain in "Private Benjamin" (1980), meanwhile, showed a nuanced yet disciplined reining in of her flair for the outlandish, and she won a supporting Oscar nomination for her efforts.

Brennan recreated her role (and won an Emmy) as the hardened Captain Lewis in the early 80s sitcom of the same name. Her career, though, was put on hold for several years after a car accident confined her to a wheelchair. Brennan was later quite open about the dangers of becoming addicted to prescription painkillers, and successfully resumed her acting career in 1985. Her feature films ("Clue" 1985, "Texasville" 1990, "Jeepers Creepers" 2001) have generally been a bit disappointing, but Brennan has managed to enliven the small screen since the late 80s with memorable TV guest spots, including Emmy-nominated turns on "Newhart" and "thirtysomething".