Sidney Webster Fish (March 16, 1885 – February 5, 1950) was an American lawyer and military officer who retired from the law and moved to California, becoming a rancher at the Palo Corona Ranch.

Fish was born on March 16, 1885, in New York City and was named after his uncle, Sidney Webster.^{[lower-alpha 1]} A member of the prominent Fish family, he was the youngest of four children of Stuyvesant Fish (1851–1923) and Marian Graves Anthon Fish (1853–1915), a leader of the "The 400". His two surviving siblings were Marian Anthon Fish (1880–1944),^[3][4] who married (and divorced) Albert Zabriskie Gray (a son of Judge John Clinton Gray,^[5][6][7] and Stuyvesant Fish Jr.,^[8] who married Isabelle Mildred Dick (a daughter of Evans R. Dick.^[9] Another brother, Livingston Fish, was born and died before Sidney was born.^[10]

His paternal grandparents were Hamilton Fish, the 16th Governor of New York, a U.S. Senator, and U.S. Secretary of State,^{[11][lower-alpha 2]} and Julia Ursin Niemcewicz (née Kean) Fish (sister of Col. John Kean), a descendant of New Jersey governor William Livingston.^[14] His maternal grandparents were Sarah Attwood (née Meert) Athon and Gen. William Henry Anthon, a successful lawyer and Staten Island Assemblyman who was a son of jurist John Anthon.^[15]

Fish prepared for college at Groton School before graduating from Harvard University, in 1908, and then Columbia Law School.^[16]

After his admission to the bar, he practiced law until 1928.^[16] He was a partner in the firm of Colgate, Parker & Co. with Craig Colgate, Prescott Erskine Wood, Henry S. Parker, Frank Hamilton Davis and Darragh A. Park. In 1921, the firm reorganized as Parker & Company when Colgate, Wood and special partner Louis du Pont Irving withdrew; Fish then became a special partner.^[17]

On September 18, 1915, Fish married Olga Martha Wiborg (1890–1937) at St. Luke's Church in East Hampton, New York. The wedding was quiet due the recent death of his mother.^[21] They spent their honeymoon aboard Harold Vanderbilt's yacht Vagrant.^[22] Olga was a daughter of Frank Bestow Wiborg and sister to socialite Sara Sherman Wiborg and playwright Mary Hoyt Wiborg.^[23] They had a country home known as "Duck Pond" in Roslyn, New York adjoining the August Belmont place,^[24] and in North Hempstead, New York adjacent to the estates of Mrs. Frederick Guest, Clarence Mackay, and Harry Payne Whitney.^[25] They sold it in 1929,^[25] and bought a house in East Hampton, where they were known for their entertaining.^[26] Before her death, they were the parents of:

• Sidney Stuyvesant Fish (1921–1988),^[24][27][18] who married Virginia "Ginny" Small, a daughter of James Small of Pawtucket, Rhode Island, in 1954.^[28][29] They divorced in 1960.^[30] She later married Frank Rothwell,^[31] and he married Diana Fish.

In 1939, he married Esther (née Foss) Moore Roark (1894–1954),^[32] the daughter of Massachusetts Governor Eugene Noble Foss. She had previously been married to George Gordon Moore, a polo player whom she divorced in 1933, and Aiden Roark, another polo player whom she married in 1934 and divorced in 1937.^[33][34][35]

He died in Carmel on February 5, 1950, and was buried at Monterey City Cemetery.^[16] His widow died in November 1954.^[36]