Regis Henri Post (January 28, 1870 – October 5, 1944) was a New York politician and Governor of Puerto Rico from April 17, 1907 to November 6, 1909. He was born in Suffolk County, New York.
Post was born in Bayport, New York, the son of Albert Kintzing Post(1843-1872) and Marie Post(née de Trobriand, 1845-1926). His maternal grandfather was Régis de Trobriand. He had an older sister, Lina Post Webster, and an older brother, Waldron Kintzing Post Sr. His father drowned at the age of 29 on Long Island when Regis was only two. His mother remarried to his father's 2nd cousin once removed, Charles Alfred Post (1844-1921). Regis had two step-sisters from this union, Beatrice Post Candler and Edith Post Gallatin. Post graduated from Harvard University in 1891 where he was a member of The Delphic Club.
He was a member of the New York State Assembly (Suffolk Co., 2nd D.) in 1899 and 1900.
He was appointed by President Theodore Roosevelt as Auditor of Puerto Rico in 1903, as Secretary of Puerto Rico in 1904, and as Governor in 1907. Post held the office of Governor from April 18, 1907 to November 5, 1909. His governorship was extremely controversial, as his frequent disagreements with the Puerto Rico Legislature led to the Legislature's failure to pass any budget in 1909, resulting in a political crisis on the island and passage of the Olmsted Amendment at the request of President William Howard Taft.
Following Post's time in Puerto Rico, he worked with the American Ambulance Corps in France from 1913 to 1914. He joined the American Red Cross in 1917.
He married Carolyn Beatrice Post, daughter of Colonel Henry A. V. Post and his 2nd cousin once removed, on March 6, 1895. They had a son, Regis Henri Post Jr.(February 17, 1897). In 1916, Post was discovered by his wife having an affair and they separated. She filed for divorce in 1922. He married Leila Ellis in 1925. She died in 1931. Post married thirdly Marguerite Denis de Lagarde on April 5, 1933. She was his distant cousin. Marguerite's great-niece through her sister was Mimi Lee.