William Pennington (May 4, 1796-February 16, 1862) was an American lawyer and politician.
Born in Newark, New Jersey, he graduated from Princeton University in 1813. He was a clerk of the United States district court 1815 to 1826 and then studied law on his own with Theodore Frelinghuysen. He began practicing in Newark in 1820.
He was a member of the New Jersey General Assembly from 1828 to 1834, and then Governor of New Jersey from 1837 to 1843.
He was appointed Governor of Minnesota Territory by President Millard Fillmore but declined to accept.
He was elected as a Republican to the 36th Congress and was elected Speaker of the United States House of Representatives that same term after months where the House was unable to decide on a candidate (the Republicans had a plurality, but not a majority, and the Southern Oppositionists who held the balance of power were unwilling to support either a radical Republican or a Democrat). He was an unsuccessful candidate for reelection in 1860 to the 37th Congress.
He died in Newark.