William Henry Seward (May 16, 1801–October 10, 1872) was United States Secretary of State under Abraham Lincoln and Andrew Johnson. He attended Union College, studying law, and graduated in 1820, with high honors. He then stopped his law practice to become a politician.

His parents were Samuel Sweezy Seward and Mary (Jennings) Seward. He was married to Frances Adeline Miller. They had two daughters and three sons. The daughters were Cornelia Seward (1835-1836), and Francis Adeline Seward (1844-1866). The three sons were Frederick William Seward (1830-1915), William Henry Seward Jr. (1839-1920), and Augustus Henry Seward (1826-1876).

Seward served as a state senator of New York from 1831 to 1834, as Governor of New York from 1839 to 1843, and as a United States Senator from New York from 1849 through 1861. He was elected as a Whig in 1849, and reelected in 1855 as a Republican.

Abraham Lincoln appointed him Secretary of State in 1861 and he served until 1869. Seward survived an assassination attempt on April 14, 1865 (the same night Abraham Lincoln was shot) from Lewis Payne, an associate of John Wilkes Booth, who broke into Seward's bedroom and stabbed him repeatedly.

As Secretary of State, he fought for the U.S. purchase of Alaska which he finally negotiated to acquire from Russia for $7,200,000 on March 30, 1867. This translated into approximately 2 cents per acre ($4.94 per km²) for 586,412 square miles (1,518,800 km²) of territory, more than twice the size of Texas. The purchase of this frontier land ("Seward's Icebox") was mocked as "Seward's Folly" and Andrew Johnson's "polar bear garden". Currently, Alaska celebrates the purchase on Seward's Day, the last Monday of March.

His portrait appeared on the 1891 series U.S. fifty dollar note.

Preceded by: Jeremiah S. Black	United States Secretary of State	Succeeded by: Elihu B. Washburne
Preceded by: William L. Marcy	Governor of New York	Succeeded by: William C. Bouck

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