Mary Loos (May 6, 1910 – October 11, 2004) was an American actress, screenwriter, TV writer, and novelist. She was occasionally credited under her full name, Mary Anita Loos. Born in San Diego, she was the daughter of Dr. Clifford Loos, co-founder of the Ross-Loos Medical Clinic and the Ross-Loos Medical Group, the first health maintenance organization (HMO) in the United States. She was the niece of screenwriter Anita Loos. Mary Loos died in Monterey, California, aged 94, due to complications following a stroke.