Mary Loretta "Mariette" Hartley (born June 21, 1940) is an American character actress.

Hartley was born in Weston, Connecticut, the daughter of Mary Ickes “Polly” (née Watson), a manager and saleswoman, and Paul Hembree Hartley, an account executive. Her maternal grandfather was psychologist John B. Watson (through Watson’s daughter from his first marriage) and her maternal grandmother was the sister of politician Harold L. Ickes. In her autobiography, Breaking The Silence, written with Anne Commire, Hartley talked about her struggles with psychological problems, pointing directly at Watson’s practical application of his theories as the source of the dysfunction in his family. She has also spoken in public about her experience of bipolar disorder, and was a founder of the American Foundation for Suicide Prevention.

Hartley began her career in her teens as a stage actress, coached and mentored by the noted Eva Le Gallienne. Her film career began with Ride the High Country (1962), a western with actors Randolph Scott and Joel McCrea, and directed by Sam Peckinpah. She also had a supporting role in Alfred Hitchcock’s Marnie (1964).