Sunday Reed (born Lelda Sunday Baillieu) (15 October 1905 – 15 December 1981) was an Australian patron of the arts. Along with her husband, John Reed, she established what is now the Heide Museum of Modern Art.

Reed was born on 15 October 1905 in Melbourne, Australia, to Arthur Sydney Baillieu and Ethel Mary Baillieu (née Ham). She was a member of Melbourne's Baillieu family and the niece of William Baillieu, one of Australia's richest men. She was the third of four children and was homeschooled by a governess until she was 15. Reed finished her education at St Catherine's School, Toorak.

In Melbourne, Reed met Leonard Quinn, an American living in England. They were married on 31 December 1926 at Sorrento, Victoria and traveled in France and England for two years. Reed was diagnosed with gonorrhoea in 1929. The disease and several operations including a hysterectomy left her unable to bear children and deaf in her right ear; after her diagnosis, Quinn deserted her in England. Through family influence and connections, she was able to obtain a divorce from him in June 1931. She met solicitor John Reed at a tennis party in 1930. They married on 13 January 1932 at St Paul's Cathedral, Melbourne. Their marriage was recorded with the state but not with the church.

In the 1930s, Reed studied art under George Bell in his Bourke Street Studio School in Melbourne. Her only remaining work is a landscape drawing, showing her skill with colour and form.

In 1934, the Reeds purchased a former dairy farm on the Yarra River at Heidelberg, Victoria, now Bulleen, which became known as "Heide". They were both interested in many forms of art, including jazz, poetry, and writers. The couple hosted a variety of artists, for whom Reed would cook. According to Andrew Stephens, talented artists at Heide "helped shape Australian art from the 1930s on". The Reeds lived on the property until their deaths in 1981, a short time after the property had become the Heide Museum of Modern Art.

Reed cultivated a selection of wild roses, along with many other flowers. In 2015, about 150 of the 250 bushes she planted remained. She was resourceful in obtaining cuttings and plants, having some imported from overseas. The Reeds also sought out nurseries specialising in old roses, and sourced plants from Alister Clark, who bred some of Australia's more popular roses.

The couple supported the Communist Party of Australia (CPA). John helped fund CPA candidates in federal elections.

The Reeds took over care of and eventually adopted Joy Hester's son Sweeney after Hester was diagnosed with Hodgkin's Lymphoma in 1947.