Horatio King (June 21, 1811–May 20, 1897) was a Postmaster General of the United States.

Born in Paris, Maine, he received a common school education, and at the age of 18 entered the office of the Paris, Maine, Jeffersonian, where he learned printing, afterward becoming owner and editor of the paper. In 1833 he moved it to Portland, where he published it until 1838. In 1839 he went to Washington, D. C., having been appointed clerk in the post office department, and was gradually promoted. In 1854 he was appointed first assistant postmaster-general, and in January, 1861, while acting as postmaster-general, he was questioned by a member of congress from South Carolina with regard to the franking privilege. In his reply Mr. King was the first officially to deny the power of a state to separate from the Union. He was then appointed Postmaster General, serving from February 12 until March 7, 1861. On retiring from office he remained in Washington, D.C. during the Civil War, serving on a board of commissioners to carry into execution the emancipation law in the District of Columbia. After his retirement from office Mr. King practiced in Washington as an attorney before the executive department and international commissions. He was active in procuring the passage of three acts in 1874, 1879, and 1885 respectively, requiring the use of the official "penalty envelope," which has secured a large saving to the government. He also took an active part, in the work of completing the Washington Monument, serving as secretary of the Monument Society from 1881. Mr. King has been a frequent contributor to the press, and has published An Oration before the Union Literary Society of Washington (Washington, D.C., 1841), and Sketches of Travel; or, Twelve Months in Europe (1878). His son Horatio Collins King was also a notable figure.

Source: Appleton's Cyclopedia, 1888