Myrna Loy was born Myrna Adele Williams on 2 August 1905 in the small ranching community of Radersburg, Montana, and grew up mainly in nearby Helena. Her father, David Franklin Williams, was a rancher, banker and the youngest man ever elected to the Montana state legislature; her mother, Adelle Johnson, was of Scottish and Swedish descent. Loy's Welsh ancestry came through her father's side: her paternal grandfather, David Thomas Williams, was born in Glamorgan, Wales, and emigrated to the United States via Liverpool in 1856 before settling as a rancher in the Montana Territory.
Loy moved to Los Angeles with her mother as a teenager after her father's death in the 1918 influenza pandemic, and broke into films in the silent era, initially typecast in exotic and often villainous roles because of her striking looks. Her career changed dramatically in 1934 when she was cast as the witty, martini-drinking Nora Charles opposite William Powell in 'The Thin Man'. The pairing was an immediate sensation, and Loy and Powell went on to make six 'Thin Man' films together between 1934 and 1947, cementing her reputation as one of Hollywood's most gifted comedic and dramatic actresses.
Among her best-remembered performances is Milly Stephenson in William Wyler's 'The Best Years of Our Lives' (1946), a drama about veterans returning home after the Second World War that is regularly ranked among the finest American films ever made. During the war itself, Loy largely stepped back from acting to work for the Red Cross and other relief organisations, and she remained a committed campaigner throughout her life, later serving as a member of the US Commission to UNESCO.
Although never nominated for a competitive Academy Award, Loy was honoured with an Honorary Oscar in 1991 in recognition of her career and her off-screen work. She continued to work in film, television and on stage into old age, and died in New York City on 14 December 1993 at the age of 88. Her paternal grandfather's emigration from Glamorgan remains the documented root of her family's Welsh connection, even though Loy herself was born, raised and based entirely in Montana and California.