Mary Grace King (née McSween) was the first wife of Tom King and the mother of Jimmy, Matthew, Carl and Max.

In the 1980s, Mary became ill with terminal cancer and Tom hired a nurse, Carrie Nicholls, to look after her. Mary eventually died in February 1986 but during her illness Tom and Carrie began an affair, which resulted in Carrie giving birth to Tom's illegitimate daughter Scarlett in 1991. When Scarlett's existence was revealed to the King brothers shortly after Tom's death during Christmas 2006, Carl thought of her existence as a betrayal to Mary's memory.

Mary is now buried in the Emmerdale cemetery, along with youngest son Max, who died in 2005.