Samuel Hoar (May 18, 1778 – November 2, 1856) was a United States lawyer and politician. A member of a prominent political family in Massachusetts, he was a leading 19th century lawyer of that state. He was associated with the Federalist Party until its decline after the War of 1812. Over his career, Hoar developed a reputation as a prominent Massachusetts anti-slavery politician and spokesperson. He became a leading member of the Massachusetts Whig Party, a leading and founding member of the Massachusetts Free Soil Party, and a founding member and chair of the committee that organized the founding convention for the Massachusetts Republican Party in 1854.