Edward Parker Deacon (October 2, 1844 – July 5, 1901)^[1] was an American heir known for killing his wife's lover in her apartments at Cannes, France.

Deacon was born in Paris on October 2, 1844, the "descendant of an old and once distinguished family" from Boston.^[2] His parents were Edward Preble Deacon (1813–1851) and Sarah Annabella (née Parker) Deacon (1821–1900). He had a brother named Austin Deacon. His father had served as an attaché of the U.S. Legation in Paris under General Lewis Cass.^[3]

His paternal grandparents were Commodore David Deacon and Anna Hutchinson Deacon. His maternal grandparents were Peter Parker and Elizabeth Allston (née Read) Parker. His maternal aunt, Ellen Parker, was the wife of Albert Gallatin Van Zandt, and his uncle, Harleston Parker, married Adeline Ellen Reynolds and was the father of architect J. Harleston Parker.

On April 29, 1879, he married Florence Baldwin (1859–1919) in New York City. Florence, who spent much of her life in Rome, was the daughter of Rear Admiral Charles Henry Baldwin and Pamelia Caroline (née Tolfree) Baldwin.^[4] Before their eventual divorce,^{[lower-alpha 1]} they were the parents of four girls (and one boy who died in infancy):^[5]

• Gladys Marie Deacon (1881–1977),^[6] who married Charles Spencer-Churchill, 9th Duke of Marlborough in 1921 after his divorce from Consuelo Vanderbilt.^{[lower-alpha 2][9]}
• Ida Audrey Deacon (1884–1904), who died unmarried at age 19 of heart disease.^[8]
• Edith Florence Deacon (1887–1965), who was engaged to George Lee Peabody but he died before they married;^[10] she later married Henry Gunther Gray, son of John Clinton Gray, in 1919.^[11]
• Dorothy Evelyn Deacon (1891–1960), who married Prince Albert Radziwiłł, a grandson of Prince Antoni Wilhelm Radziwiłł,^[12] in 1910.^[13] They divorced and she married Count Paul Pálffy ab Erdöd;^{[lower-alpha 3]} they also divorced.^[15]