Margaret Sidney Davies (14 December 1884 – 13 March 1963), was a Welsh art collector and patron of the arts. With her sister Gwendoline, she bequeathed a total of 260 works, particularly strong in Impressionist and 20th-century art, which formed the basis of the present-day National Museum Wales' international collection. The sisters started the Gregynog Press in 1922 and the Gregynog Music Festival in 1933.