Mary Katherine Jaynes Shell, previously Mary Hosking, usually known as Mary K. Shell (born February 9, 1927), is the first woman to have served as mayor of Bakersfield, California (1981–1985) and only the second woman to have served on the Kern County Board of Supervisors (1985–1997). At the time of her retirement from public office, Shell was termed by the Bakersfield Californian as "the most popular politician in Kern County history." She is the widow of Joseph C. Shell, Sr.